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Analysis of the Election Systems & Software, Inc

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1. The ease of reading and altering PEB memory facilitates a number of powerful attacks against a precinct s results and even against county wide results An attacker who extracts the correct EQC cryptographic key and ballot definition can perform any election function on a corresponding iVotronic terminal including en abling voting closing the terminal loading firmware and so on An attacker who has access to a precinct s main PEB when the polls are being closed can alter the precinct s reported vote tallies and as noted in Section 6 3 can inject code that takes control over the county wide back end system and that thus affects the results reported for all of a county s precincts 51 Individual precinct poll workers have many duties that involve handling PEBs throughout the election day whenever a voter votes for example and so are in a natural position to carry out attacks that involve altering or reading PEB memory without engaging in suspicious activity 6 1 2 Physical security locks and seals Many aspects of the ES amp S system s security as a whole depend on the integrity of the interfaces and re movable media associated with precinct equipment Some of these interfaces and media are protected by software security e g access passwords encryption etc potential attacks against such mechanisms are discussed in other sections of this report Many interfaces and media are also protected partly or entirely by physi
2. Windows page layout tool used to design optical scan paper ballots It is also sometimes referred to by an older name Ballot Image Manager BIM in documentation and source code ESSIM uses the IFF and BSC files exported from EDM to obtain the information to be displayed on ballots including both information for the voter candidates races proposals etc and information for the back end optical scanners ballot codes etc The layout specific data is stored in a Ballot Layout File When ballot design is finalized ESSIM exports another IFF file with a different file extension to be used in the Hardware Programming Manager as well as PDF ballots to be sent to a printing company iVotronic Image Manager The iVotronic Image Manager iVIM is a Java Windows application for designing text graphical and audio ballots for the iVotronic DRM iVIM relies on a MySQL database server to store its settings which can either be installed on the same machine as iVIM or accessed remotely The main input to iVIM is an XML file exported by EDM along with graphical templates bundled with iVIM Once layout is complete iVIM exports the ballots as an iVotronic Election Definition file and a folder containing bitmap images and file hierarchy for the iVotronic Compact Flash card Audio ballots for ADA voting are not managed within iVIM Instead an HTML document listing the necessary recordings and filenames to save them as is produced along with the othe
3. The provided documentation is wholly insufficient for election workers to complete the above requirements During our ten week analysis of the ES amp S voting system we were unable to configure an election from start to finish in the process experiencing unexplained and frequent software crashes despite receiving several hours of vendor training and access to user manuals According to the office of the Ohio Secretary of State a majority of counties in Ohio rely at least partially on ES amp S technicians to generate their election definitions and tally election results practices we presume are due to the complexity of the configuration process and the lack of pertinent documentation Such outsourc ing introduces security risks as the maintainers of the election delegate critical work to the voting machines vendor Subtle miscommunication between election officials and ES amp S regarding the wide assortment of configuration options could lead to incorrect configurations and tallying Since they will not necessarily cause election Pre Tests or logic and accuracy tests to fail incorrect configurations may be particularly difficult to detect Such a scenario appears to have transpired in the November 2007 elections in Ohio The Mount Vernon news service has recently reported that a contract employee of ES amp S double counted more than 400 ballots by failing to clear one report before running another report resulting in incorrect elect
4. and knowledge of the appropriate passwords can carry out the following actions e lock the terminal e close the terminal early adjust the date and time which in effect may also close the terminal e disable or enable audio ballots for ADA versions of the iVotronic e mis calibrate the touchscreen see Section 7 2 13 7 2 9 Emulated Initialization PEB can close polls and reset passwords Description An initialization PEB may be used to set terminal menu passwords to arbitrary values and close the polls early The initialization PEB can be inserted at any time including when polls are open We have confirmed in our testing that it is straightforward to emulate an initialization PEB using a handheld device with an infrared port see Figure 7 1 The initialization process takes approximately one minute to complete and hence can easily be accomplished by a malicious voter Prerequisites A specially formatted PEB or a PEB emulator can carry out this attack No election secrets e g the EQC or the election encryption key are required Impact By closing the polls before the close of the election this attack causes denial of service against a particular iVotronic terminal Once closed an iVotronic terminal cannot be reopened unless a new ballot definition is loaded onto the terminal The initialization PEB also causes all iVotronic passwords to be set to values configured on the initialization PEB By setting these passwords t
5. and regenerate the CRC Prerequisites Access to a valid M100 PCMCIA card and a commodity PCMCIA card reader writer Impact As described in Section 6 4 CRC routines do not provide cryptographic integrity protection An attacker can write anything to the PCMCIA card regenerate the CRC and it will be accepted as valid by the M100 7 3 7 The M100 PCMCIA cards do not contain cryptographic integrity checks Description There is no cryptographic integrity protection used on the M100 PCMCIA card This means that there is no way to verify that the data on the card was created from an authorized source Prerequisites Knowledge of the CRCs as in Section 7 3 6 Impact An attacker can arbitrarily change data on the card The altered data would then be accepted as valid by either Unity or the M100 7 3 8 M100 uses data offsets defined on the PCMCIA card to determine pointers used by the firmware Description During the boot process the M100 loads a number of structures from the ballot PCMCIA Some of these structures contain a reference to other structures in the form of an offset value After the structures have been loaded a function is invoked to translate each offset to a pointer This is accomplished by replacing each offset with the value of the base pointer increased by the offset Since the attacker can control the offset values and since the function does not check that the resulting pointers are correct it is possible to make these p
6. overflows integer overflows and format string attacks More modern programming languages for example David A Wheeler SLOCCount URL http www dwheeler com sloccount 83 Component Platform Language Lines of Code Unity 3 0 1 1 Intel 686 Pentium BAT scripts 364 136 C C COBOL Java Visual Basic AIMS 1 2 Intel 686 Pentium C SQL Vi 59 984 sual Basic iVotronic firmware 9 1 6 4 Intel 80386 C x86 assem 87 157 bly iVotronic PIC source code Microchip PIC Microcontroller C PIC assem 1 753 bly M100 firmware 5 2 1 0 Intel 80286 C x86 assem 29 952 bly shell script M650 firmware 2 1 0 0 Intel 686 Pentium C C 22 458 including display utility shell script VAT AutoMARK Intel IXP425 ARM assem 104 305 bly C C C Visual Basic Total 669 745 Figure 8 1 Platforms and lines of code associated with each component of the ES amp S system Java and C are type safe and are not susceptible to such memory violations and are therefore sometimes favored when developing security critical applications Although techniques exist for annotating C code comprising roughly 23 of the ES amp S source code to achieve type safety such approaches were not utilized 8 1 2 Third Party Software ES amp S makes use of third party software including the Windows and QNX operating systems Compact Flash device drivers and PCMCIA flash device drivers Al
7. virally to other election equipment iVotronic M100 M650 7 1 3 Unity accepts memory media with unauthorized precinct results Description Unity via the Hardware Programming Manager module passes election definition and other data to an M100 optical scanner via a PCMCIA card This card contains information identifying those precincts for which the M100 will accept ballots The election results are stored on the PCMCIA card and are transferred back to Unity on the same card for processing See Section 22 7 1 2 in the confidential Annex 60 However Unity does not check whether only the results for which the card and thus the M100 scanner were configured are actually returned A poll worker can thus take the card with election results and insert results for a precinct for which the card was not configured A malicious poll worker can therefore not only modify the results for his or her own precinct he or she can influence the results for other precincts as well We have verified experimentally that this vulnerability is exploitable When a PCMCIA card with results is entered into Unity Unity indicates how many precincts have been reported on the card Thus an attentive operator using Unity can catch this attack in case he or she has a list of cards their serial numbers and the number of precincts that should be reported for each card This attack raises a question whether a similar one can be carried via PEBs that contain res
8. with the M100 see Section 7 3 3 both firmware and ballot definitions are loaded through the same medium in this case the Zip Disk drive By surreptitiously inserting malicious firmware onto a ballot definition disk a corrupted Unity system could carry out this attack Figure 7 4 shows the display on the M650 after a forged firmware update disk was used to load unauthorized in this case benign and conspicuous software onto the machine Prerequisites To successfully load new software onto the M650 the attacker must learn the three filenames that convince the M650 that an inserted Zip Disk is a firmware update disk These filenames can be easily obtained either by cloning a legitimate firmware update disk or by examining the firmware update procedure a plaintext shell script stored in the M650 although the latter technique requires prolonged and unfettered access to the machine Any person with knowledge of these three filenames and approximately three minutes of unmonitored access to the M650 can replace all software on the machine with malware Impact An attacker who can forge a firmware update disk can take total control over the M650 This includes the ability to learn election results change results mimic the behavior of an uncompromised M650 to avoid detection thwart future attempts to load new firmware while reporting success to the operator and or cause the M650 to become inoperable until its internal storage can be reimaged
9. 2 1 0 0 WHPM 5 2 4 0 ESSCRYPT1 1 0 0 0 M650 Support Scripts 2 1 0 0 ESSCRYPT 1 8 0 0 MAKEIBIN 9 1 0 0 ESSDECPT 1 8 0 0 MPRBOOT 2 6 0 0 ESSIM 7 4 2 0 MYDLL 1 0 0 0 ESSM100 1 3 1 0 PCCARD30 3 0 0 0 ESSPCMIO 1 0 0 0 PEB PIC 1 7c ESSUTIL 1 0 0 0 PGENAZ80 1 2 0 0 43 5 5 Unity Acronyms and File Extensions ais BDF bdf BIM bin BSC bsc ebn EDM ERM ESSIM IEC IFF EEE iVIM PEB pxt and px1 RTAL Vot VVPAT xml Ballot layout file extension for ESSIM Ballot Data File EDM database file BDF file extension Ballot Image Manager see ESSIM Unencrypted iVotronic Ballot file extension created by HPM helper application used by HPM PEB writer helper application Ballot Set Collection created by EDM used by ESSIM BSC file extension Encrypted iVotronic Ballot file extension created by by HPM helper application used by HPM PEB writer helper application Election Data Manager Unity elections database program Election Reporting Manager Unity tabulation and results program alternatively called Election Report Manager and Election Results Manager in source code and documentation ES amp S Image Manager also known as BIM Unity optical scan ballot page layout program IFF file extension for HPM Intermediate Interface File ballot data file created by EDM used by ESSIM and HPM IFF file extension for ESSIM iVotronic Image Manager Unity touchscreen DRE ballot layout program P
10. Supervisor PEB to be inserted again to cast another ballot If the poll worker inserts the Supervisor PEB while holding the Vote button above the touchscreen a service menu appears This menu allows various settings of the terminal to be adjusted and also provides the interface for opening and closing the polls While in the service menu actions performed are logged to the RTAL printer 5 2 3 Real Time Audit Log Printer The Real Time Audit Log Printer RTAL is a continuous feed thermal printer manufactured by FutureLogic Inc specifically for use in DRE voting systems It performs the function of VVPAT on iVotronic machines 36 It is connected to the iVotronic by a standard 9 pin RS232 serial cable and mounted behind a plexiglass window next to the iVotronic The RTAL supports both ASCII text using several built in fonts and encodings and a bitmap mode used to print barcodes or other non text content Unlike the printer in the Communications Pack see Section 5 2 7 the RTAL collects the output in ternally The RTAL only has a motor on the collection spool making it impossible to rewind the audit log without jamming A movable carrier holds the paper mechanism independently of the print head and display window allowing for the appearance of a small backwards movement approximately 5 and the ability for the print head to back up a few lines 5 2 4 Personalized Electronic Ballot The Personalized Electronic Ballot PE
11. The PEB Reader does not contain any functionality in hardware other than this media conversion all protocol implementation for communicating with a PEB must be done in software on the device connected 37 to the PEB Reader Despite its name there is nothing preventing a PEB Reader from being used to issue commands to write to or erase a PEB if controlled by suitable software 5 2 6 Compact Flash Cards Standard Type I Compact Flash cards are used by Unity and the iVotronic to hold files too large to fit in the PEB flash storage as well as audio ballots and audit and results data Cards contain a standard FAT16 Windows filesystem and are accessed through a dedicated slot in the iVotronic and an external USB reader on the Unity PC In Windows these are mounted to the desktop and accessible to any Windows application with no special libraries The ballot data is accessed by the iVotronic on demand but the presence of the CF card is checked periodically and the iVotronic will not boot without its presence That same CF card must be present to close the polls An audit log can be saved to the card when the polls are closed It is a raw dump of the internal flash memory compressed and encrypted before saving 5 2 7 Communication Pack The Communication Pack is a briefcase containing a thermal printer a modem not used in Ohio space to store PEBs for transport and a serial cable to connect to an iVotronic A switch is used to toggle between off
12. Trail must be started The Supervisor terminal displays the Election Qualification Code EQC and then permits the qualification of PEBs to be used in the DREs Each qualified PEB is programmed with the EQC and new system passwords if changed are ready to be loaded with the ballot for the current election A PEB is programmed using a supervisor terminal which is connected through a serial port to a machine running the HPM One PEB for each precinct is chosen as the master PEB the others are referred to as supervisor PEBs A Compact Flash card one for each iVotronic used in the election must be programmed CF cards are programmed through the HPM using a standard commodity CF card reader writer At some point after the PEBs and CF cards have been programmed the blue voter terminals must be cleared and tested using a correctly programmed supervisor PEB This erases the votes and audit data from the previous election and loads the EQC and any custom passwords The Election Test menu options are only available after a terminal has been cleared and tested The iVotronic allows the following election tests e Logic and Accuracy Tests whether votes are recorded accurately e Automated Multi Vote Test tests multivote and write in option e Vote Selected Ballot Test for multiple ballot images e Manual Vote Test 40 Election Day On election day poll workers unpack and set up the blue iVotronic terminals plug in the RTAL printer and power c
13. access controls Access to the iVotronic DRE configuration is protected by several hardware and password mechanisms all of which can be defeated through apparently routine poll worker and in some cases voter access The primary mechanisms for preparing iVotronic DREs for deployment at precincts and for managing them throughout the election day e g enabling them for each voter employ the Personalized Electronic Ballot PEB interface As discussed in Chapter 5 a PEB is a small module that communicates with the iVotronic via a magnetically switched infrared IrDA bidirectional data interface on the face voter side of the terminal PEBs are used for several different kinds of functions Some of these functions are intended to be performed at the county headquarters e g loading ballot definitions and basic configurations while others are performed by poll workers e g opening the terminals at the beginning of the day enabling a voter to use a particular ballot closing the terminal and collecting vote totals In the mode used in Ohio the PEB slot is empty whenever a voter is voting PEBs are used as external memory devices that communicate through a simple protocol that allows the iVotronic to read and write memory blocks stored in the PEB Access to PEB memory is not protected by encryption or passwords although some of the data stored on them is encrypted see Section 6 4 PEBs themselves are proprietary devices and are apparently not
14. are ineffective against maliciously installed firmware which can simply bypass or omit the integrity check functions 6 3 2 Unity software No single component of the ES amp S system is more important to the integrity of election results than the central Unity election management system Unity is a complex software suite consisting of many compo nents that share a common database Securing a county s Unity system therefore depends on each of its components and on the computing platforms on which it runs Because Unity at least as used in Ohio apparently runs only in a single secure location in each county with presumably only trusted staff permitted access to the computers attack vectors involving unauthorized direct physical access by poll workers voters or others are a less significant threat here than in precinct equipment sent to the field However because the Unity system processes electronic data received from 55 precincts it is subject to a number of indirect yet devastating attacks that can originate with poll workers or voters even if they cannot themselves physically touch the Unity computers Attacks via input from precincts As discussed in Section 6 2 malicious input carried on iVotronic and M100 results media can take over the Unity system when it is loaded for counting This enables many of the most serious and comprehensive attacks we discovered Windows environment vulnerabilities The Unity software ru
15. ballot selections Description If the VOTE button is pressed while a Supervisor or Factory QA PEB is inserted into an iVotronic the iVotronic enters the service menu By pressing the VOTE button again the iVotronic enters the calibration screen mode in which the user is required to press crosshairs shown on the screen to calibrate the touchscreen s sensors By deliberately touching the screen at incorrect places it is possible to carefully miscalibrate the screen preventing the voter from making certain selections while marking a ballot Prerequisites A possibly emulated Supervisor or Factory QA PEB is required to recalibrate the iVotronic It is not necessary for the PEB to contain the correct EQC or any other election specific information No password checks are used for screen calibration so even an unqualified PEB from a different election can be used Impact By carefully miscalibrating the iVotronic a malicious voter with access to a PEB or PEB emulator can prohibit future voters from making certain ballot selections 7 2 14 Connection to RTAL VVPAT printer is physically unprotected Description The RTAL VVPAT printer is connected via an unprotected serial port on top of the iVotronic see Figure 7 2 The VVPAT printer cable is not protected by any seals or fastened by any screws and can be easily unattached by a voter Prerequisites The attacks described below require only a hardware device with a serial interface Impact A
16. card into the voting process An election insider could prepare a malicious Compact Flash card that is then sent to precincts A virus that previously compromised the Unity server see Section 7 1 could modify the Hardware Programmer Manager HPM to create malicious Compact Flash cards A poll worker could introduce a malicious Compact Flash card either before opening the polls or during a sleepover A voter could extract the Compact Flash card from the iVotronic modify it to contain the exploit and reinsert the now malicious card into the iVotronic This approach requires the voter to break and reattach seals Additionally the iVotronic will stop responding when the Compact Flash card is removed However a voter could claim that a crash occurred during the normal voting operation and convince the poll worker to reactivate the machine If the machine is reactivated the exploit code will then be executed and the iVotronic will be compromised Impact The buffer overflow exploit allows the attacker to execute arbitrary code on the iVotronic permit ting any of the actions described in Section 7 2 5 7 2 7 Buffer overflow in Supervisor iVotronic initialization process is exploitable Description The iVotronic supervisor terminal election initialization process contains a stack based buffer overflow A device that is connected to the supervisor terminal during initialization usually the Unity backend system can exploit this overflow a
17. e denying service e removing the ability to install additional firmware this subsequently makes the M100 unrecoverable unless by the use of additional hardware 75 7 3 2 The M100 does not perform cryptographic integrity checks on firmware uploads Description There are no cryptographic integrity checks on new firmware before it is uploaded onto the M100 Any correctly formatted M100 firmware including malicious code created by an attacker can be loaded onto a PCMCIA card and the M100 will accept it as valid Prerequisites An attacker needs to have knowledge of the hardware components of the M100 in order to create malicious firmware and would need physical access to the M100 in order to install it Knowledge of the hardware components of the M100 is not particularly hard to obtain and is within the scope of a sufficiently motivated attacker Impact As stated above in Section 7 3 1 the installation of malicious firmware on the M100 gives the attacker complete control of the machine 7 3 3 The M100 uses the same facility for configuring an election as it does for firmware uploads Description The procedure for installing new firmware and the procedure for loading a new election defini tion on the M100 are both performed by inserting a PCMCIA card into the PCMCIA card slot on the M100 and turning the machine on If a PCMCIA card containing malicious firmware was placed in an M100 due to issues described in Sections 7 3 1 and 7 3 2 it i
18. elections The broad scope of such attacks provides great leverage to the adversary and can be extraordinarily difficult to detect trace or recover from Both the DRE iVotronic and the precinct based optical scan M100 systems are subject to many exploitable vulnerabilities The DRE system provides more vectors for attacks that cannot be recovered from through manual recounts however While there are many specific errors and weaknesses in various parts of the ES amp S software and which are detailed in Chapter 7 there are also systemic weaknesses throughout the system s overall design and implementation These weaknesses render the system as a whole especially difficult to secure in practice We identify here four fundamental pervasive deficiencies that give rise to the most serious vulnerabilities we found e Ineffective access control e Critical errors in input processing e Ineffective protection of firmware and software e Ineffective cryptography and data authentication 6 1 Ineffective Access Control The firmware and configuration of the ES amp S precinct hardware can be easily tampered with in the field Vir tually every piece of critical data at a precinct including precinct vote tallies equipment configuration and 49 equipment firmware can be compromised through exposed interfaces without knowledge of passwords and without the use of any specialized proprietary hardware 6 1 1 iVotronic passwords and PEB based
19. end of elections to print zero count tallies and precinct results on a separate printer with removable paper The Model 100 is a machine for scanning and validating tallying paper ballots at a polling location The Model 100 uses PCMCIA Memory Cards to hold ballot definitions and tallies The Model 650 is a machine for batch scanning and tallying paper ballots at a central election office The Model 650 uses Zip Disks to hold ballot definitions and election tallies The AutoMARK Voter Assist Terminal is used by disabled voters to fill out a paper ballot without additional assistance The AutoMARK uses Compact Flash cards to load ballot definitions 32 5 2 System Components In this section we describe the different components of the ES amp S voting system in greater detail This background on the architecture and implementation will aid in understanding the vulnerabilities and attacks in subsequent chapters The ES amp S system is made up of a number of custom and off the shelf general purpose computers On top of these computers run several hundred thousand lines of source code in various pieces of software It is important to keep in mind that although they do not appear the same as your typical desktop or laptop computer all the components of the ES amp S system are fully programmable computers capable of running arbitrary software stored in easily modifiable memory Therefore use of the term firmware to refer to the software control
20. fleeing voter s ballot will be discarded and there will be one less vote for the undesired candidate Case 2 Voter voted for the attacker s candidate If the fleeing voter voted for the candidate that the attacker wants to win then the malicious firmware completes the voting process by faking the pressing of the VOTE button This results in another vote being cast for the attacker s candidate This could result in a lower than average number of fleeing voters Also it might be possible to detect that all of the fleeing voters had voted against the attacker s candidate Since this could possibly arouse suspicion the firmware only completes the voting process for a certain percentage of the fleeing voter ballots that are for the attacker s candidate 9 3 4 Attack Scenario peb 4 Canceling a Vote by Faking a Fleeing Voter In this scenario the iVotronic machine is compromised in the same way as described for the peb 1 scenario However in this case the firmware fakes a fleeing voter If a voter does not select the candidate that the attacker wants the malicious firmware intercepts the confirmation page s confirm function and pretends to cast the ballot the normal thank you page is displayed but nothing is printed on the audit tape After Everett as in n 4 Selker and Cohen as in n 5 This differs from California where a fleeing voter s ballot is cast by the poll worker 95 waiting a few seconds during
21. for each of the races and or questions as well as a certification message The poll worker then secures the scanner key 41 After a voter has marked their ballot the ballot is scanned by inserting it into the ballot entry slot in any direction The ballot count on the display increases whenever the scanner successfully scans a ballot If there are no issues with the ballot such as over or under voting the operator can press accept to have the ballot deposited into the ballot box If there are concerns with the ballot such as over or under voting there is an option to press reject and retrieve the ballot The ballot will then be spoiled and the voter is usually issued a new ballot and directed to a voting booth Vote Tallying The M100 keeps a running tally of votes internally and on the PCMCIA card To close the polls the scanner key is inserted and turned to the OPEN CLOSE POLL position The scanner will automatically print reports that may include a Status report Poll or Precinct report Certification report and or an Audit Log report The POLLS CLOSED menu will appear after printing and results is complete The PCMCIA card is removed the ballot boxes removed from the cabinet and the boxes cards and the printed reports are returned to Election Central 5 3 4 Centrally Counted Optical Scan Voting The M650 is an optical scan machine for processing batches of ballots It is usually kept at Election Central The election process for an M6
22. improved In almost every case it was not actually necessary to operate the locks since the equipment cases could generally be opened by removing a few screws and the locks bypassed altogether Other physical security mechanisms depend on tamper evident seals As noted in Chapter 9 we were not provided with samples of the seals used in every county and so cannot conclusively comment on the security of the particular seals used in Ohio However we note that all but the most sophisticated commercially available tamper seals are often surprisingly easily to defeat Even if effective at revealing tampering seals are inherently limited in the protection they provide As noted in Chapter 3 and in other reports seals do not prevent tampering at best they can defect it But in an election even reliable detection of tampering may be unsatisfying since if a seal is found to be broken once For the first weeks of the project we did not have the correct keys for much of the equipment we frequently had to pick the locks in order to conduct our analysis Roger G Johnston Tamper indicating seals American Scientist 94 November Decemeber 2006 Matt Blaze etal Source Code Review of the Sequoia Voting System University of California Berkeley under contract to the California Secretary of State July 20 2007 URL http www sos ca gov elections voting_systems ttbr sequoia source public jul26 pdf 52 polling has started it is u
23. inserting a special firmware PCMCIA card These are usually provided by the ES amp S service representatives The development of a malicious firmware was complicated by the lack of tools required to both compile the M100 sources and build the final image For this scenario the QNX filesystem extraction tool and the PCMCIA read write tool described in Sections 9 1 4 and 9 1 6 respectively were used to craft a malicious PCMCIA update card The malicious firmware that we developed behaves exactly like the original firmware except that it gives all the votes to the first candidate To accomplish this we had to extract the binaries from the firmware installed on the M100 and patch them to steal votes See Section 22 9 3 7 in the Annex of the private report for the actual string 97 When the card is inserted in the M100 and it is powered up the card will be accepted and the CRC check will be passed because the card was crafted with an appropriate CRC value and in the appropriate format Next the M100 will display a menu asking the user if he she wants to replace the firmware A yes response results in the firmware being updated 9 3 10 Attack Scenario m100 2 M100 Denial of Service The M100 optical scanner which is used to count physical election ballots uses ballot PCMCIA cards to get ballot information from Unity This scenario uses the PCMCIA read write tool described in Section 9 1 4 to craft a malicious PCMCIA ballot card wh
24. installer for the iVotronic Image Manager includes an install of Sun Java Run time Environment 1 4 2_8 This version of Java has a known exploitable vulnerability in its GIF image display code iVotronic Image Manager is written in Java and supports importing GIF graphics for political parties These graphics are displayed by the iVotronic Image Manager when previewing ballots Anyone The Unity Election Reporting Manager Users Guide 8US CERT Vulnerability Note VU 388289 Sun Microsystems Java GIF image processing buffer overflow http www kb cert org vuls id 388289 January 2007 64 who provides a GIF image to be imported into iVIM or any GIF images downloaded from e g Google could potentially exercise this exploit We have not experimentally confirmed that this vulnerability is exploitable in iVotronic Image Manager Impact A malicious GIF file could lead to arbitrary code executing as the user running iVotronic Image Manager and writing to any files allowed for that user 7 2 iVotronic 7 2 1 Election encryption decryption key is recoverable from a PEB Description The per election encryption key used to protect vote and audit data is trivially recoverable from a qualified PEB The election key is itself encrypted using the election qualification code EQC and is stored as ciphertext on the PEB However the EQC is written to the PEB in unencrypted form Hence access to the PEB reveals the EQC which can then be used to d
25. modify these data A linear cyclic redundancy code CRC is included with the PCMCIA data but an attacker can easily calculate this CRC codes are not keyed and are not designed to provide security against deliberate data modification 6 4 2 Ineffective iVotronic cryptography The iVotronic DRE uses cryptography to protect data stored on the PEB and in the CF card The Blow fish cipher is used Unfortunately the manner in which the encrypted data is stored on the PEBs ef Blowfish is a popular public domain cipher algorithm from the 1990 s 57 fectively neutralizes the cryptographic protection The PEB contains an EQC encoded using an unkeyed non cryptographic algorithm The EQC is used to encrypt the Blowfish key which is used to the encrypt the rest of the data on the PEB That is although much of data on the PEB is encrypted there is unencrypted information stored along with it that allows an attacker to easily discover the key 6 4 3 Poor data validation of precinct results in Unity The obvious attacks enabled by the lack of cryptographic protection of precinct media include alteration or forgery of data unauthorized loading of firmware as discussed in the rest of this report Additional vulnerabilities are introduced by Unity s poor validation of various reported precinct data In particular the precinct results reported on an incoming M100 PCMCIA card are not checked against the precincts for which the card was orig
26. printer and modem modes and the case contains batteries for when a wall outlet is unavailable The communication pack is used by disconnecting the RTAL if present from an iVotronic supervisor or voter and connecting the communication pack s serial cable when prompted by the iVotronic The iVotronic then controls the printer or modem in the communication pack and prompts the user when to disconnect the communications pack and reconnect the RTAL 5 2 8 Model 100 The Model 100 M100 is a voter operated optical scan ballot counter intended for use at the polling location It is mounted on top of a secure ballot box which holds the accepted and counted ballots and provides physical security for the M100 The M100 we were provided with used one set of identically keyed locks for physical protection of the M100 and ballots and a second differently keyed lock for selecting the mode of the M100 The M100 contains an Intel 286 microprocessor with 2MB of RAM and runs the QNX embedded operating system from an internal 512KB flash memory A thermal receipt printer and 40x4 character LCD text display are built in and a standard parallel printer port is available for connecting an external printer when a parallel port connection is detected the M100 automatically switches all printed output to use it instead of the built in thermal printer In addition to the optical scanner the inputs to the M100 are 4 programmable buttons positioned below the LCD di
27. reads data blocks stored on the PEB 90 e it writes blocks of data to the PEB By leveraging these basic operations pebserial allows one to dump the contents of a PEB and to create PEBs with arbitrary contents Pebserial can correctly handle both unencrypted and encrypted PEBs For encrypted PEBs identified by a particular value in one of the fields of the EQC the data is stored in encrypted format using the Blowfish algorithm It is trivial to determine the encryption key because the key is formed from fields of the EQC which is always stored in the clear in the PEB Therefore encryption adds no additional security anyone with access to a PEB can easily bypass its encryption and access its contents 9 1 3 The iVotronic Serial Debugger In order to facilitate the development of the iVotronic exploits we created a specialized firmware with de bugging support The debugging firmware allows the exploit developer to attach a computer to the i Votronic via a serial cable connected to the iVotronic s serial port The attached computer runs a debugger program gdb over the serial port The attached debugger offers full debugging support of the iVotronic including memory inspection and single stepping and partial support for breakpoints The debugging firmware was created by attaching a debugging stub to the original firmware The stub is provided as part of the gdb debugger The stub can be concatenated to the original firmware and only
28. running an election It may be possible to deploy a reduced subset of the ES amp S hardware and software that excludes com ponents that present the greatest risks For example a system that uses only centrally counted optical scan hardware eliminates many of the threats of precinct based attacks We defer to the expertise of the Ohio election officials to determine whether it is possible to use a version of the ES amp S system with reduced functionality in a way that presents an acceptable level of risk to the integrity of their elections 58 CHAPTER 7 ES amp S SPECIFIC WEAKNESSES AND THEIR IMPLICATIONS In this chapter we describe specific weaknesses found in the reviewed ES amp S systems For each discovered vulnerability we detail the prerequisites necessary to compromise security and or reliability as well as the impact of such attacks Since we made no attempt to subject the various ES amp S software and hardware systems to equal scrutiny the number of findings among the perspective ES amp S components should not be used to infer any conclusions regarding their relative security We did however concentrate our efforts on areas we deemed most apropos to security and reliability It is worth emphasizing that we do not assert that the vulnerabilities described in this chapter constitute a complete and exhaustive listing of the security weaknesses exhibited by the reviewed ES amp S systems The reviewed components consist of nearly 670 0
29. they have no intrinsic security properties of their own and they may pass through many hands on the way to polling places during the polling day and back from polling places That is it is simple to read or alter data on these media and many people may have the opportunity to do so during an election For example 1 Votronic PEBs are handled by poll workers all through an election day with memory that can be read or written with a standard palmtop computer and a small magnet PCMCIA and CF cards similarly can be readily read or altered with standard laptop computers The usual approach indeed generally the only practical approach for securing data stored on such media is the use of cryptographic techniques that prevent meaningful access to data without knowledge of the correct key Unfortunately the ES amp S system does not employ cryptography at all in the M100 based optical scan system The iVotronic DRE system does use cryptography but errors in its implementation render the protection completely ineffective The lack of effective cryptographic protection enables a large fraction of the exploitable vulnerabilities discussed in this report 6 4 1 Unauthenticated M100 data M100 PCMCIA cards are used to load ballot definitions and firmware into the M100 and to report tallies back to the Unity system The data for each of these functions are not cryptographically protected an attacker with access to an M100 PCMCIA card can easily forge or
30. throughout the election Additionally if the order of voters is also known the attacker can determine how a particular voter voted 7 2 17 VVPAT barcodes contain vote information Description After a voter casts a ballot a barcode encoding the voter s ballot selections is appended to the VVPAT record An example of such a barcode is depicted in Figure 7 3 Under the assumption that most voters cannot decipher barcodes encoding vote information on a VVPAT that cannot easily be voter verified constitutes a dangerous and unnecessary practice The purpose of such barcodes is unclear As noted in Section 7 2 14 Ohio law stipulates that for any recount of an election in which ballots are cast using a direct recording electronic voting machine with a voter verified paper audit trail the voter verified paper audit trail shall serve as the official ballot to be recounted The tabulation of election results based on barcodes rather than on human comprehendible text eliminates the safeguards promised by voter verified paper audit trails Interestingly the iVotronic operator s manual recommends the use of a 2D barcode reader for tabulating votes in the event of a recount although 4See Section 22 7 2 15 in the confidential Annex SSee Section 22 7 2 16 in the confidential Annex See Section 22 7 2 17 in the confidential Annex 17 Ohio Revised Code O R C 3506 18 Electronic voting machine verified paper audit tra
31. which time the voter likely leaves the booth the firmware again displays the confirmation page After some time the firmware calls the fleeing voter code and the machine will start chirping A poll worker will think the voter was a fleeing voter and in accordance with Ohio s procedures the ballot will be canceled 9 3 5 Attack Scenario flash 1 iVotronic Denial of Service This scenario causes an iVotronic to crash when a malicious flash card is inserted and the iVotronic attempts to read an image file from the card A malicious flash card was crafted to take advantage of the flash card hot spot buffer overflow vulnerability discussed in Section 7 2 6 and the flash card was introduced into the system using one of the methods presented in that same section In Section 7 2 6 we saw that there are two different code patterns that are used in the iVotronic to read image headers For this attack code that uses the first pattern for reading the image header is exploited Recall that executing this code allows an attacker to overwrite the stack return address but not with data under the attacker s control therefore a system crash is likely A denial of service attack was implemented by replacing one of the system s election image files with a file that overflows the hotspot handling function that uses the first code pattern Because the attacker cannot control what gets written on the stack he she cannot introduce malicious code However tri
32. 00 lines of code encompassing twelve programming languages and five hardware platforms Given the extraordinary scope and complexity of the ES amp S voting system it is infeasible that any study could comprehensively analyze all hardware components and software modules in a reasonable amount of time Consequently it would be improper to conclude that a particular system can be fixed merely by repairing the vulnerabilities listed in this chapter particularly given the overarching engineering issues identified in Chapter 8 Throughout this chapter vulnerability details containing proprietary information are provided in a sep arate confidential annex References to such proprietary details are denoted using footnotes 7 1 Unity 7 1 1 Unity ERM buffer overflow when reading a Master PEB Description The Election Reporting Manager ERM component of Unity is used to compile results from the precincts The most common method of delivering the results is on a Master PEB There is a stack based buffer overflow in the ERM which can be exploited when election pre election or testing results are processed To exploit this vulnerability an attacker can create a specially crafted PEB that will allow arbitrary code execution As a result an attacker has the ability to gain full control of the machine running the Unity server The EQC on the results PEBs is not checked so an attacker does not need to know a valid EQC to create a malicious PEB P
33. 50 requires the HPM and a commodity Zip Disk reader writer Preparation The M650 reads the proper election definition and firmware from a Zip disk The Zip disk with the election definition is placed in the Zip drive in the M650 and the scanner is powered on This message will appear once the scanner has initialized Press Stop to Keep XXXXX Press Start to Load YYYYY Zip where XXXXX is the name of the election currently in the machine and YYYYY is the name of the election on the Zip disk If start is pressed the M650 displays a menu option for zeroing out previous election totals this is optional and prints out a readiness report The machine is now ready for ballot tabulation Election Day Vote Tallying Ballots are transported to Election Central from the various precincts in secured transfer cases On arrival the cases are opened and an election worker processes the ballots into the M650 To tally ballots an election worker places them in batches into the M650 input hopper and presses start Counted ballots are stored in an output hopper and must be removed by hand before the next batch of ballots is tabulated The result totals are stored internally and the election worker needs to periodically press the Save button on the M650 to store the results to the Zip disk for transfer to the Unity ERM The manual recommends saving and transferring the results on the Zip disk to the machine running the ERM every time the hopper is emptied It i
34. B is a palm sized device containing a PIC microcontroller 2MB of flash storage a bi directional infrared IR transceiver and battery The PEB is activated by a magnetic reed switch and contains a magnet to activate the corresponding reed switch in the iVotronic PEB socket In addition to the flash storage the PIC microcontroller contains a small amount of non volatile storage which is burned to the PIC during the PEB manufacturing process This area contains the PEB firmware PEB firmware version number PEB hardware revision number PEB serial number and PEB Kind vari able The microcontroller firmware implements the passive half of a very simple command response protocol between the PEB and host over the PEB IR port using IrDA SIR Serial Infrared The host sends the PEB one of several commands along with an address and fixed mount of data depending on the command and the PEB performs the command and returns a response and command determined amount of data The primary operation is reading and writing 128 byte blocks of the PEB s flash memory or verifying the integrity of blocks using a cyclic redundancy check CRC stored with each block In addition the serial number PEB kind battery voltage can all be retrieved but not modified by the host device While all PEBs are internally identical in construction they are discernible from one another by the read only information burned in the PIC their serial number and more importa
35. CRC check and the attacker can choose data to be such that the CRC check passes Prerequisites The attacker must be able to obtain a PEB possibly a new one or one used in previous elections and must be able to return it with the PEBs that are to be processed by Unity Impact An attacker can take advantage of this vulnerability to perform the buffer overflow attack on Unity see Section 7 1 1 or to return incorrect results for the precinct s for which the PEB was configured Note that the attacker does not need access to a PEB used in an election that is in progress and does not need to know the correct EQC 7 1 7 Unity contains large pieces of duplicated code Description There are three copies of a large segment of code in C performing the same task namely processing audit data The three copies might have been obtained by cut and paste and slightly modified in subsequent versions This is an unsafe programming practice The result is that the three copies have slightly different security properties For instance there are security issues in one of the three copies see Sections 7 1 8 and 7 1 5 This does not create a vulnerability by itself therefore we do not list prerequisites and impact here The purpose of this section is to point out an instance of an unsafe programming style that may lead to security problems 3See Section 22 7 1 6 in the confidential Annex 4See Section 22 7 1 7 in the confidential Annex 62 7 1 8
36. DB9 serial port at the top of the iVotronic and the other to an infrared transceiver The external serial port is used to connect to the RTAL printer see Section 5 2 3 or a Communications Pack see Section 5 2 7 in the field and to a computer running Unity HPM or ERM in the central election office The infrared serial port is used to communicate with the Personalized Electronic Ballot hardware tokens see Section 5 2 4 The left side of the iVotronic case has a molded socket to hold a PEB allowing IR communication as well as activation of the iVotronic power switch through a magnetic reed switch There are two IR transceivers one on the inside of the PEB socket and a second on the outer edge of the iVotronic case These two transceivers are multiplexed onto the single serial port and only one can be used at a time In addition to the internal solid state flash memory a Compact Flash slot is located next to the printer serial port The inserted CF card is accessed using a third party library which implements the necessary filesystem code There are two types of iVotronic terminals used in elections red Supervisor iVotronics are used by poll workers or elections officials to administer the election and blue Voter iVotronics are used by voters to cast their votes Every iVotronic has a serial number which is programmed into a PIC microcontroller during manufacturing Except for this serial number and the outward appearance all iVotronic
37. M is considered to be a part of the Audit Manager s functionality The user manual for EDM explicitly states that the Audit Manager provides security for election and should always be used Scenario unity 1 in Section 9 3 demonstrates an attack using this vulnerability Prerequisites The attacker needs access to the Unity election management system The attacker also needs to know the name of the table that contains users information This can either be guessed or found in the Unity documentation for example it is in the functional specification for EDM Impact This injection works by bypassing authentication for EDM ESSIM and Audit Manager As a result if user accounts are not enforced at the OS level anybody could login to any of the three applications Once the attacker is logged on he she could view in clear text or change the iVotronic passwords which do not seem be available in clear text outside of EDM or he she could change logs for EDM and ESSIM using the Audit Manager The same SQL injection does not work for other Unity modules since they use different logging and au thentication mechanisms or they do not use any authentication mechanism at all 7 1 10 An M100 PCMCIA card can be read multiple times without warning Description In the ERM module of Unity if the operator chooses the add to mode settings when pro gt See Section 22 7 1 8 in the confidential Annex See Section 22 7 1 9 in the confidentia
38. Part II Analysis of the Election Systems amp Software Inc Voting Systems CHAPTER 4 ES amp S EXECUTIVE SUMMARY This part of the EVEREST report evaluates the ability of the ES amp S Unity EMS iVotronic DRE and M100 M650 based optical scan voting systems to conduct trustworthy elections The review team was provided access to the ES amp S source code and election equipment The reviewers studied these materials in order to identify security issues that might be exploited to affect an election As part of that analysis the reviewers were asked to identify where possible practices that limit or neutralize the impact of discovered issues Our analysis suggests that the ES amp S Unity EMS iVotronic DRE and M100 optical scan systems lack the fundamental technical controls necessary to guarantee a trustworthy election under operational conditions Exploitable vulnerabilities allow even persons with limited access voters and precinct poll workers to compromise voting machines and precinct results and in some cases to inject and spread software viruses into the central election management system Such compromises render the election result subject to subtle manipulations potentially across election cycles These vulnerabilities arise from several pervasive critical failures of the ES amp S system e Failure to protect election data and software The firmware and configuration of the ES amp S precinct hardware can be easily ta
39. Unity contains many small buffer overflows Description There are numerous occurrences of unsafe memory accesses throughout the Unity code This is indicative of fragile programming style which might lead to errors that lead to unpredictable behavior of the program and or open vectors of attack In parts of code that process incoming election results and audit data there are numerous instances of small buffer overflows 1 or 2 bytes There are also hardcoded buffer overflows i e memory write accesses that are determined by a constant fixed in the code and that are such that the access is guaranteed to be beyond allocated memory While these problems will not result in the attacker running arbitrary code they cause memory corruption In case of hardcoded buffer overflows the corruption of memory will occur regardless of activities of an attacker This does not create an exploitable vulnerability by itself therefore we do not list prerequisites and impact here The purpose of this section is to point out an instance of an unsafe programming style that may lead to security problems 7 1 9 SQL injection to bypass authentication in EDM ESSIM and Audit Manager Description The authentication process for the Election Data Manager EDM Ballot Image Manager ESSIM and Audit Manager components of the Unity election management system can be bypassed with a simple SQL attack The authentication code used by both EDM and ESSI
40. a PA by the University of Pennsylvania team and in Santa Barbara CA by the WebWise Se curity Inc team Team personnel are identified as authors in the front matter of this report We frequently consulted with the project s procedural and document consultants and with the Pennsylvania State Univer sity team The issues and commentary described in this section of the report are reflective of our analysis of the ES amp S system only None of the included material should be considered to apply to either the Hart or Premier systems nor should any statement be construed to be making any quantitative or qualitative comparisons of the different systems Such comparisons are expressly outside the scope of the review and we have not developed any opinions on the relative merits of any one system with respect to the others Nothing in this review should be considered as a positive or negative commentary on electronic voting in general The remainder of this part of this report is structured as follows We begin in the next section by giving a brief overview of the ES amp S system and its use in Ohio elections Chapter 6 broadly characterizes the se curity and reliability of the ES amp S system by highlighting the most serious architectural and systemic issues encountered in the review Chapter 7 catalogs various specific software vulnerabilities that we discovered Chapter 8 outlines software quality and software engineering risks arising from the system s d
41. a few pointers in the original firmware need to be changed in order to hook the stub into the firmware No source code is needed in order to perform the modifications Any attacker with access to a binary firmware image can create a firmware with debugging support 9 1 4 A tool to read and write M100 PCMCIA memory cards We developed a tool that contains python scripts to read and write PCMCIA cards and firmware update cards The tool also sets all of the headers and CRC values appropriately This enables us to put any malicious software or data that we want on the cards 9 1 5 The JTAG hardware debugger The iVotronic DRE is equipped with a JTAG connector on the circuit board JTAG is a standard for low level hardware debugging We utilized this port in order to read and write directly to the flash chips without the help of the firmware We needed this functionality mainly for two reasons First we wanted to validate that the firmware installed on the iVotronic was the firmware that had been placed in escrow and also that no other code was installed on the machine Checking the version number displayed by the iVotronic would not suffice since any malicious firmware could provide us with the correct version number Second we needed a way to recover from a situation where the firmware was corrupted in such a way that upgrading the firmware the usual way would not work Since we were going to create a modified firmware for the voting machine chances w
42. ables A properly programmed CF card must already be installed in the terminal this is usually done at Election Central and a tamper evident security seal usually placed over the CF slot before powering the terminal on A master PEB is required to open each terminal for voting and only that same master PEB can be used to close the terminal after the polls have closed At this time a zero tape showing no votes cast may be printed but this is optional For each voter a supervisor PEB containing the ballot images must be inserted into the iVotronic Inser tion of the PEB turns on the iVotronic checks the EQC and initializes loads in the ballot The poll worker removes the supervisor PEB the voter votes the RTAL printer prints the results and the electronic ballot is stored internally in the iVotronic until the terminal is closed Vote Tallying To close a terminal the master PEB is inserted which collects and stores the tabulated data copies of the images of the ballots cast and time and date information At closing the iVotronic firmware automatically uploads Audit Data onto the CF card At this time a results tape can be printed using a special external printer The results tape zero tapes Compact Flash cards and Master PEB are then returned to Election Central At Election Central the results can be imported into ERM using either the Master PEBs or the Audit Image on the CF cards 5 3 3 Precinct Based Optical Scan Voting Th
43. achine to halt until it is rebooted It may also be possible to corrupt election results although such an attack has not been confirmed 7 4 4 M650 fails to protect against integer overflows Description The M650 dynamically allocates memory on the heap to store indices for the precincts these indices are later used in the tabulation process The amount of allocated memory is based on the number of precincts reported in the election definition For example if there are 10 precincts and 20 bytes are required to store an index for each precinct then 200 bytes should be allocated However the M650 fails to ensure that the product of the number of precincts and the storage requirement of each precinct does not exceed the maximum value that can be represented as an integer If the product exceeds this limit then an integer overflow occurs in which case the result of the multiplication rolls over and appears quite small and insufficient memory is allocated An attacker can force this integer overflow by specifying a large number of precincts in the election definition file allowing him to write arbitrary data onto the heap the amount of data is limited only by the storage capacity of the Zip Disk Prerequisites To overflow the heap the attacker needs a Zip Disk containing a seemingly valid election definition that is one that conforms to the data structures defined in the M650 Functional Specification document The election definitio
44. ailable 99 100
45. ains an entire election database of its own which can either be imported from EDM s BDF or re entered using the AIMS interface Documentation recommends the later approach be taken to avoid errors in the conversion Once the election database has been created visual audio and translated ballots are designed for each type of printed ballot The final configuration is copied to a Compact Flash card to be inserted in the AutoMARK device 5 2 2 iVotronic The iVotronic is a touchscreen DRE based around an Intel 386 processor with 1 MB of SRAM There are four internal flash memory devices One of these holds the iVotronic firmware and is memory mapped directly into the address space of the CPU to avoid using the limited amount of RAM to hold instruction code The other three flash devices provide redundant storage for ballot and vote data At power up and periodically during operation the contents of the three memories are compared to one another to detect any corruption The iVotronic does not run anything resembling a modern operating system There is a single process started at boot which runs in an event interrupt driven loop Multiple threads memory protection dynamic memory allocation exception handlers and similar constructs are unavailable 35 The primary user input device to the iVotronic is an LCD touchscreen which is wired to the CPU as a serial device There are two other serial ports on the iVotronic one connected to a standard
46. an quickly i e within a few minutes conduct the following attacks e Delete all previously recorded vote data e Upload new firmware to the iVotronic through the Compact Flash interface Since the Compact Flash card slot is normally protected by a tamper evident seal of questionable quality see Section 6 1 2 uploading firmware in an undetectable manner requires the removal and subsequently replacement or reattachment of the security seal e Exploit the buffer overflow in the terminal opening process see Section 7 2 5 to take complete control of the iVotronic This includes the ability to upload firmware via either the unprotected serial port or the iVotronic s PEB interface 70 7 2 12 Emulated Factory QA PEB can lock a terminal Description A possibly emulated Factory QA PEB permits a malicious voter to access the services menu without a password and lock the terminal The locked terminal cannot be used for voting until it is unlocked by keying in the unlock password Prerequisites A Factory QA PEB or emulator is sufficient to lock the terminal No election specific secrets e g EQCs or election encryption keys are required Impact A locked terminal cannot be used for voting until it is unlocked by keying in the unlock password Assuming poll workers know the unlock password this is a minor denial of service attack which disrupts the voting process 7 2 13 iVotronic touchscreens can be miscalibrated to deny certain
47. and results counters The PCMCIA memory card is also used to upgrade the firmware of aM100 When a correctly formatted card is present at power up the M100 will prompt the user to copy a new firmware image to the internal flash memory Unlike the Compact Flash cards and Zip disks used by other equipment the PCMCIA card does not contain a recognizable filesystem and cannot be accessed directly through Windows Instead a library for the OmniDrive USB reader is required to read or write data 5 2 10 Model 650 The Model 650 M650 is a centralized high speed optical ballot counter intended for use at a central elec tions office It scans batches of ballots possibly from multiple precincts and tabulates results to be trans ferred to Unity The M650 contains an Intel Pentium processor and runs the QNX real time operating system off of an internal solid state hard drive There are two standard parallel printer ports which must be connected to printers for operation to begin Additionally an Iomega Zip 100 drive is used to transfer ballot definitions and perform firmware updates to the M650 and carry results from the M650 to Unity The M650 has a control panel on its front with buttons to start and stop scanning as well as set the mode of operation An LED display provides feedback to the operator Inside the chassis the motherboard and daughter cards are accessible behind a locked panel There are two RS232 serial ports and a PS2 keyboard mouse po
48. are module and we found practical attacks that can be mounted by almost any participant in an election For this reason the team feels strongly that any prudent approach to securing ES amp S based elections must include a substantial re engineering of the software and firmware architecture to make it secure by design It may be possible to deploy a reduced subset of the ES amp S hardware and software that excludes com ponents that present the greatest risks For example a system that uses only centrally counted optical scan hardware eliminates many of the threats of precinct based attacks We defer to the expertise of the Ohio election officials to determine whether it is possible to use a version of the ES amp S system with reduced functionality in a way that presents an acceptable level of risk to the integrity of their elections 30 CHAPTER 5 ES amp S SYSTEM OVERVIEW The following chapters detail the ES amp S portion of the EVEREST review Readers are directed to Part I of this report for a discussion of the review s goals and methodologies Those readers not experienced in information security or Ohio election practices are also encouraged to read the threat model in Chapter 3 The content in that chapter is instrumental in gaining a detailed understanding of the substance and impact of the issues identified throughout The ES amp S source code analysis and penetration testing exercises reported here were conducted in Philadelphi
49. be easily made from commodity ink jet printer supplies The M650 accepts forged ballots made of commodity paper in a variety of weights Prerequisites The M650 is a batch scanner used primarily to scan mail in absentee ballots To be scanned forgeries must be mailed to the appropriate office in official election envelopes which of course may also be forged gt See Section 22 7 4 4 in the confidential Annex Election Systems and Software Inc Software Specifications Model 650 Central Count Ballot Tabulator version 2 0 0 0 as in n 22 81 Impact A motivated forger can produce paper ballots that visually appear legitimate and that are accepted by the M650 82 CHAPTER 8 ES amp S SOFTWARE ENGINEERING ISSUES It is widely recognized that large and complex software is more difficult to implement correctly and securely than small and less intricate software The diffuse control flow data sources databases data structures and usage patterns inherent in large systems decrease the ability to reason about the behavior of the software Consequently complex design and implementation permit the introduction of bugs some of which may be exploited by malicious adversaries Software engineering techniques best practice methodologies and tools used to develop and test com plex software attempt to reduce the number of such bugs Although no software engineering technique can eliminate all complexity or guaran
50. cal mechanisms locks seals and procedures Although this study did not aim to conduct an exhaustive analysis of the physical security of the ES amp S equipment we found many of the basic physical security features that protect precinct hardware to be ineffective or easily defeated iVotronic Several features of the iVotronic s physical security were especially problematic e A primary mechanism for logging events including those potentially associated with an attack on the iVotronic terminal is the RTAL printer However the cable connecting the printer is readily accessible to the voter and can be removed easily and without tools or overtly suspicious activity It is possible to for an attacker to suppress logging simply by unplugging the cable It is also easy for an attacker to print arbitrary messages on the printer including ballot choices by connecting a small handheld computer to the printer cable e The PEB interface on the iVotronic terminal is exposed and readily accessible to the user during voting As noted above this facilitates several important attacks Locks and seals The mechanical locks supplied with all of the ES amp S precinct equipment sent to the source code review team were uniformly of very low security designs that can be easily picked or otherwise bypassed Many locks use keys that are apparently identical in equipment shipped to different customers and so would provide little security even if the locks were
51. ccess to the iVotronic s serial interface enables the following attacks e A voter who can access the election services menu e g by emulating a Factory QA PEB see Sec tion 7 2 10 can download encrypted audit log information to a device with a serial port Here the attacker disconnects the RTAL printer and connects the iVotronic s serial port to a handheld device If the attacker has knowledge of the election encryption key e g by probing a PEB see Section 7 2 1 s he can decrypt the audit log to obtain voting records e The iVotronic communicates with the printer using a simple protocol via the serial port By connecting a device to the exposed printer connector it is possible to print counterfeit audit information as well as additional VVPAT ballots This is particularly troublesome given that Ohio law specifies that for any recount of an election in which ballots are cast using a direct recording electronic voting machine 71 l m NE nn hig 4 Aad TAY PR teg 4 ar NN TET E gt maS A a RS NBGA Any A Ve or br Abbess Y wes ses a gt Figure 7 2 The connection to the RTAL VVPAT printer port is physically unprotected with a voter verified paper audit trail the voter verified paper audit trail shall serve as the official ballot to be recounted e The RTAL VVPAT printer has the ability to rewind the printer tape by approximately one half inch This scrollback limitation is due to hardware so a mali
52. ce exploits peb 1 peb 2 peb 3 and peb 4 could all be realized using this image overflow vulnerability The attacker need only change the code introduced Recall that in Section7 2 6 there were ten different locations in the iVotronic s code that read image headers using the second of the two code patterns Although the attack presented in this section was for only one of the ten occurrences of the second pattern the other instances could be used for delivering malicious code in the same way 96 9 3 7 Attack Scenario unity 1 Unrestricted Access to Unity Ballot Preparation Software The Unity election management system is used to prepare ballots for all of the iVotronics and M100s in all of the precincts Unfortunately as shown in Section 7 1 9 the authentication process for the Election Data Manager EDM Ballot Image Manager ESSIM and Audit Manager components of the Unity election management system can be bypassed with a simple SQL injection This gives the attacker unrestricted access to these components This scenario demonstrates an SQL injection exploit that uses a secret constant string as the username parameter and the password parameter is left blank We tried this for EDM ESSIM and for the Audit Manager In all cases the user was logged on with no further authentication checks 9 3 8 Attack Scenario unity 2 Compromising the Unity Election Reporting Manager The Unity election management system is used to compile result
53. ce the voter touches the cast ballot button and confirms the vote by touching the confirm button the malicious firmware takes over That is the malicious firmware does not intercept the normal process until after the cast ballot and confirm pages have been presented to the voter At this point the malicious firmware changes the voter s electronic ballot and the RTAL prints Race S Canceled Candidate X and Race S Selected Candidate Y where Y is the attacker s choice for Race S The RTAL then immediately prints Accepted the other normal tabulation information the bar code and 4S Everett The Usability of Electronic Voting Machines and How Votes Can Be Changed Without Detection Ph D thesis Rice University 2007 T Selker and S Cohen An active approach to voting verification May 2005 28 Technical report 94 the time stamp This whole printing process plus the paper scrolling up and out of site takes less than 4 seconds The printer is also scrolling forward and back when printing this information which makes any attempt to read what is printed even more difficult After carefully checking casting and confirming their votes most voters do not pay attention to what is printed on the RTAL Also unless the voter is watching closely as the RTAL is printing he she will not be able to see what was printed This version of the attack is more likely to evade detection since the stealing hap
54. cious voter cannot sufficiently rewind the printer to read printouts from previous voter sessions An attacker can utilize this functionality to repeatedly print over the same line of text creating the appearance of a paper jam This attack can diminish voter confidence in the election particularly since VVPAT records are considered the official ballots of record e A malicious voter can implant a small serial device between the printer cable and the iVotronic s serial interface If not removed such a device could intercept all communication between the terminal and the printer including voter selections The recorded votes may be recovered either by adding a wireless transmitter to the serial device or by retrieving the device at the close of an election perhaps by another voter acting as an accomplice e A small device may be attached to the iVotronic s serial interface that mimics the VVPAT RTAL printer The iVotronic will incorrectly detect an attached printer although no future audit information or VVPAT ballots will be printed to the disconnected VVPAT RTAL printer 3 Ohio Revised Code O R C 3506 18 Electronic voting machine verified paper audit trail as official ballot in recount URL http codes ohio gov orc 3506 72 7 2 15 Audit data is insufficiently randomized Description The iVotronic does not properly randomize voter selections in its audit logs To maximize voter privacy voter selections should be rand
55. commercially available except through ES amp S However they employ a widely used infrared communication standard called IrDA In spite of the proprietary nature of the official PEB we found it to be relatively simple to emulate a PEB to an iVotronic or to read or alter the contents of a PEB using only inexpensive and commercially available IrDA based computing devices such as Palm Pilot PDAs and various mobile telephones Most of the administrative and poll worker functions of the iVotronic e g pre election ballot loading enabling voting etc require the insertion of a properly configured supervisor PEB and in some cases the entry of a password on the terminal touchscreen However we found it to be possible to defeat both of these security mechanisms This makes practical several possible attacks at polling stations Unauthorized screen calibration and configuration One of the simplest and yet most important configuration parameters of the iVotronic DRE is the calibration of its touchscreen input sensors Calibration which can be performed in the field through the screen itself affects how voters tactile input maps to different locations on the screen If the procedure is performed incorrectly or has been deliberately altered voter choices might not be correctly recorded It is easy to surreptitiously re calibrate the screen of an iVotronic terminal in a way that allows most input to behave normally but that den
56. cpy and sprintf functions are frequently used throughout the various ES amp S system components These functions copy data into a buffer under the unchecked assumption that the target buffer is sufficiently large If the size of the copied data exceeds the size of the buffer the strcpy and sprintf functions write beyond the allocated space potentially overflowing onto other data or process flow structures Such a condition is known as a buffer overflow and represents a common if not the most common cause of software exploits and instability 86 To prevent possible buffer overflows memory safe versions of strcpy and sprintf should instead be used The strncpy and snprintf functions note the additional n take as a parameter the maximum number of bytes to write to the target buffer eliminating the possibility of writing beyond the allocated space assuming correct buffer sizes are provided Static source code analysis tools such as Fortify SCA can be used to locate the use of memory unsafe string operations in a system s source code In addition some compilers including newer versions of Microsoft s Visual C compiler produce compile time warnings when the strcpy and sprintf functions are used e Using the Fortify SCA source code security analyzer we were able to quickly identify several pro gramming errors Although such security analysis tools are imperfect they serve as a useful means to quickly locate security vulnerabilitie
57. d by firmware stored on an internal flash memory chip The firmware is designed to be field updated through an admin istrative menu function with new firmware loaded though the terminal s CF card interface Four security mechanisms are intended to protect against unauthorized firmware loading e Access to the firmware update menu function requires a supervisor or QA PEB e A 6 8 character password is required to enable firmware update e The firmware is loaded through the CF card interface which can be protected by a sealed sliding cover e The firmware update function is disabled while the polls are open Unfortunately these mechanisms are ineffective We found several practical ways for an attacker to bypass each of these security mechanisms and successfully replace or alter the iVotronic firmware without knowledge of any passwords or secret election parameters possession of a PEB or breaking any seals We found ways to carry out these attacks even when the polls are open It is possible for example for a voter with no inside assistance to load new firmware into an iVotronic after he or she is finished voting We found at least three different vectors that an attacker could exploit to load unauthorized iVotronic firmware under various circumstances 54 Via direct replacement of the internal flash chip The iVotronic terminal housing can be disassembled easily without breaking the seal that protects the CF slot Disassembly requi
58. e When the iVotronic doors are sealed there is not enough space to insert a PEB in the iVotronic slot We discovered however that by placing a strong magnet on the outside of the iVotronic doors when they are closed and by slipping the inside of a PEB which is quite thin behind the door and close to the PEB slot but not in the slot we were able to activate the PEB and load malicious firmware on the iVotronic This was the same malicious firmware as is used for Scenario peb 1 in Section 9 3 1 If the doors are only sealed on the top as we have seen in some literature we could slip the whole PEB under the bottom of the doors and do the same thing again using a strong magnet on the outside of the closed iVotronic door 9 3 Successful Attack Scenarios We implemented and tested all of the attack scenarios in this section 9 3 1 Attack Scenario peb 1 Changing an Unattentive Voter s Vote This scenario assumes an unattentive voter A malicious PEB was crafted to use the PEB ballot header overflow vulnerability discussed in Section 7 2 5 and the PEB was introduced into the system using one of the methods presented in that same section The malicious code on the PEB contained the payload binary 93 as presented in Section 9 1 1 Before the election the PEB is inserted in an iVotronic machine When the PEB is inserted the exploit is automatically triggered and as a result the malicious firmware is installed on the iVotronic The maliciou
59. e M100 is an optical scan machine used to process individual paper ballots It can be operated by the voter or by a poll worker The election process for an M100 machine requires the HPM a commodity PCMCIA reader writer and two physical keys the scanner key and the ballot box key Preparation The M100 reads the proper election definition from a prepared PCMCIA card This card is programmed at Election Central using the HPM and a locally connected PCMCIA reader writer The PCMCIA card can then be inserted into the M100 and the slot secured with a tamper evident seal Election Day A poll worker unpacks and sets up the M100 Usual procedures include using the ballot box key to open the emergency bin and compartment side doors to verify that the bins are empty The compartments are then re locked and the key secured The M100 requires a key scanner key to power on A poll worker inserts this key into the power on switch and turns the switch to the Open Close Polls position The scanner loads the election definition from the PCMCIA card into its operating system The scanner will display S MODE in the upper left corner of the LCD screen and the message ELECTION CARD INSERTED OPEN POLLS NOW The poll worker then turns the scanner key to the VOTE position After initializing the scanner auto matically prints an Initial State Report plus any other reports it was programmed to print This may include a report showing no votes on the scanner
60. e election day and in future elections Any attack that compromises iVotronic firmware is extremely serious it can be very difficult to detect whether such firmware has been used in a live election or meaningfully recover once it has The firmware controls every aspect of the ballot presented to voters the recorded votes and the interface to the tally system Because the RTAL printer is under the control of the firmware compromised firmware can easily print misleading choices that evade the notice of voters or that cancels the printed ballot replacing it with other choices after the voter has left The discovery of compromised firmware at a terminal casts doubt upon every vote cast at that machine and because of additional bugs in the Unity back end on the integrity of the results reported countywide as well Compounding the problem is the fact that there are apparently no tools available to counties in the ES amp S system that reliably extract or audit the actual firmware present in any given terminal The version number is displayed at boot time but that is not a reliable indication of whether the firmware has been compromised since the message is part of the firmware itself Compromised firmware can display any version number that it wishes to impersonate The iVotronic firmware code includes a number of internal consistency checks intended to detect cor rupted firmware While these checks may be able to detect accidental memory errors they
61. e firmware is loaded from the same PCMCIA cards used to load ballot definitions corrupt firmware can also be loaded into the M100 by a corrupted Unity system when an election is provisioned M100 firmware controls how ballot definitions are interpreted the counting and recording of votes the format of data returned to Unity and the acceptance and rejection of ballots The consequences of corrupt M100 firmware are serious especially given the vulnerabilities in Unity results processing However since the paper ballots remain available they can be recounted if an attack might have occurred Unfortunately as with the iVotronic there is no mechanism for reliably determining or auditing the actual firmware installed in an M100 so attacks on these devices may be difficult to detect or confirm 6 3 4 Viral propagation The software or firmware of almost every major component of the ES amp S system can be altered or replaced by input from the other components with which it communicates In particular note that by design or software flaw e The Unity system software can be modified by election results media originating from iVotronics and M100s due to Unity buffer overflows e The iVotronic firmware can be modified by configuration media originating from the Unity system due to iVotronic buffer overflows 56 e The M100 firmware can be modified by configuration media originating from the Unity system due to the design of the M100 firmware
62. e found it to be straightforward to exploit the iVotronic buffer overflows in several different ways by emulation of a QA or supervisor PEB with a palmtop computer or by writing data to a precinct s supervisor PEB at various times while opening polls and during the polling day and with various degrees of access as a poll worker or as a voter The exposed nature of the PEB port and the many different scenarios under which it can be exploited make attacks against the iVotronic very difficult to effectively guard against under operational election conditions 6 3 Ineffectively Protected Software and Firmware The integrity of election results depends heavily on the integrity of the software and firmware that runs the central election management system and the precinct hardware The consequences of any attack that alters replaces or otherwise compromises this software or firmware are sweeping and often impossible to recover from The security features that protect election software and firmware from unauthorized tampering are therefore among the most critically important safeguards in the system as a whole We found exploitable vulnerabilities that allow an attacker to replace or alter the firmware and software of virtually every component of the ES amp S system either by circumventing access controls or by triggering software errors 6 3 1 iVotronic firmware The iVotronic terminal is based on an Intel 80386 embedded computer processor controlle
63. e serial port of the machine running ERM using the same command line tool used by HPM Once retrieved from memory devices the COBOL code processes the results files and records the official election results ERM has features for producing election reports per contest per precinct or summary results Additional details that can be reported include the totals for each type of ES amp S tabulation device Audit Manager The Election Data Manager and ES amp S Image Manager as well as Audit Manager itself contain a mecha nism for logging use and modification of the Unity election database files to a Microsoft Access database Audit Manager provides a way of viewing these logs Other components of Unity developed in languages other than Microsoft Access iVIM HPM ERM have no support for recording actions in the Audit Manager log Additionally Audit Manager relies on EDM and ESSIM to dutifully update the Access database Audit Manager is incapable of detecting changes to critical files performed outside of Unity tools AutoMARK Information Management System The AutoMARK Information Management System AIMS is a standalone Windows application used to configure the AutoMARK Voter Assist Terminal to read and mark optical scan ballots produced in Unity with EDM and ESSIM Although bundled as part of the Unity suite the AutoMARK and AIMS were not developed by ES amp S and are not tightly coupled with any of the other Unity programs or files AIMS cont
64. ecrypt the encrypted election key This is the electronic equivalent to storing a secret in an impenetrable safe and then painting the safe s combination on its door Prerequisites Recovering the encryption key requires physical access to a qualified PEB and the ability to communicate to it via an infrared IR link Impact The encryption key is used by Unity and iVotronics to protect election definitions vote information and audit logs Knowledge of the encryption key and physical access to a PEB permits the following actions e Arbitrary modification of data on the PEB including election results if the PEB has been used to collect votes from an iVotronic and the election definition e Decryption of audit logs stored on the PEB or a Compact Flash card e The ability to emulate PEBs e g using a Palm Pilot with an IR port that are accepted by iVotronics see Section 7 2 2 7 2 2 PEBs may be emulated using infrared capable devices Description The iVotronic communicates with PEBs using a proprietary IR protocol Any device with IR capability can be used to emulate a PEB Since PEBs and the iVotronic contain magnets and use magnetic switches to detect each other s presence see Section 5 2 4 communicating with the iVotronic requires close proximity to the i1Votronic s voter facing PEB interface As is illustrated in Figure 7 1 we were able to emulate PEBs using a commodity Palm Pilot and a small magnet the construction of s
65. ement the propagation of mali cious code from an infected iVotronic DRE to another iVotronic DRE where infected refers to a running malicious firmware Similarly the payload also implements spreading from an infected iVotronic DRE to the Unity election management system such that subsequent PEBs generated from an infected Unity instal lation will propagate this payload to all iVotronic DREs in its jurisdiction In this manner a persistent viral infection of malicious code in an ES amp S electronic voting infrastructure has been implemented In the case of spreading from iVotronic to iVotronic a PEB is infected when it is inserted into an infected DRE to activate it for voting This allows a malicious firmware to infect a master PEB used for pre election logic and accuracy tests Then on election day the master PEB can spread the infection to all machines in a polling location as they are activated Spreading from iVotronic to Unity is accomplished in a similar manner except that a PEB is infected when inserted to collect votes as the terminal is closed The PEB used for this function will subsequently be loaded into Unity Taking advantage of scenario unity 2 in Section 9 3 8 it can be used as a vector for spreading the virus to election central That is when the PEB is loaded into Unity a program will be installed to infect all future PEBs generated from that Unity installation with the malicious code to implement the previous component o
66. en without a PEB and so may represent a serious practical threat We note that iVotronic behavior consistent with such attacks has been reported in various jurisdictions during actual elections Undocumented PEB features can be used to bypass password checks Many of the more sensitive iVotronic administrative functions closing the polls clearing the terminal etc require the entry of passwords in addition to the insertion of a supervisor PEB However there is a special Quality Assurance QA PEB type recognized by the iVotronic firmware that behaves essentially as a supervisor PEB but that when used does not require the entry of any passwords This PEB type does not appear to have been described or documented in any of the ES amp S manuals or training materials provided to our review This undocumented PEB feature can be used to neutralize the security of any iVotronic administration features that depend on passwords no matter how carefully passwords are managed by a county Anyone with such a PEB whether it was supplied by ES amp S stolen or emulated with a palmtop computer effec tively has a back door that bypasses this basic security check As noted above a simple Palm Pilot type device can be programmed to emulate a PEB QA PEBs are no more difficult to emulate than regular super visor PEBs they are similar to supervisor PEBs but with a single character changed in the communication protocol Note that while the QA PEB bypa
67. er is not considered suspicious The lack of factory installed seals allows anyone with access to the equipment to open it and tamper with the inside The counties could install seals on receipt of the equipment but the equipment we received did not have any traces of county installed seals We find it unlikely that the county officials would have removed all traces of the seals before shipping the equipment to us It is more likely that the equipment never was sealed In addition to the seals the M100 optical scanner has a number of locks that are supposed to keep intruders from getting at the scanner itself and at the PCMCIA cards It was our experience that an inexperienced lock picker in our group was able to successfully pick the M100 lock in a matter of a few seconds using two paper clips After the lock was opened the scanner could be opened by removing a few screws The PCMCIA cards could then be removed and reinserted by removing the two small nuts and bolts that hold the protective covers over the cards These covers are supposed to have seals on them but the cover fixture can be removed and put back on without disturbing the seals The PEB communicates with the DRE and the PEB reader using an infrared link The PEB contains a battery that is normally in the off state In order to turn the PEB on a magnet has to be in proximity of the bottom of the device The PEB slot on the iVotronic contains a magnet and an infrared link for this purpos
68. ere that the machine could end up completely disabled if we made any mistakes when modifying the firmware In order to communicate with the onboard flash chips we modified OpenOCD 3 which is an open source http openocd berlios de web 91 JTAG tool created for ARM processors Unfortunately the processor used by the iVotronic is drastically different from the processors supported by OpenOCD therefore we had to develop support for this proces sor The M100 scanner utilizes the same processor as the iVotronic This processor has JTAG support but the M100 is not equipped with an easy to access JTAG port In order to be able to read the firmware of the scanner and update it if necessary we mounted a JTAG connector on the scanner After dumping the content of the scanner s firmware we noticed that the firmware held in escrow was only part of the scanner s firmware The second unknown part of the firmware was located at the top 64KB of the firmware flash It appears to contain the QNX kernel but we have no way to validate this We asked ES amp S for source and binaries of this piece of the firmware but we never received it ES amp S said that the firmware is the bootloader code that is part of the burned image on the hardware chip that is installed on the motherboard as part of the manufacturing process They also said that it is write protected and cannot be changed or updated after installation on the motherboard We have no way of
69. ersonalized Electronic Ballot Hardware token used to program and vote on iVotronic DRM alternatively called Personal Electronic Ballot and Portable Electronic Ballot in source code and documentation Votronic Election Definition file extension created by iVIM used by HPM for PEB Real Time Audit Log see VVPAT Also used to refer to iVotronic with RTAL attached iVotronic Vote Results file extension created by ERM PEB reader helper application used by ERM Voter Verified Paper Audit Trail Printed record of votes cast on a DRE Ballot Foundry Election Definition file extension created by EDM used by iVIM 44 Voter iVot Merge Files Super PEB Poll Opening Closing M ter Ballot HPM ge as Files PEB i i i COBOL ERM PCMCIA M100 Datafiles 1 i ZIP l Disk M650 Election Headquarters Polling Place Figure 5 2 The major components and the flow of election data for counties using the ES amp S Unity voting system Arrows indicate direction of data flow An election begins with configuration using the Election Data Manager EDM and ends once results are tallied and reported in the Election Reporting Manager ERM 45 Figure 5 3 A blue Voter iVotronic with a Supervisor PEB inserted Figure 5 4 A red Supervisor PEB 46 SamiskZ 256 me CompactFlash Figure 5 5 A Compact Flash card used by the Voter iVotronic and AutoOMARK Figure 5 6 The ES amp S M100 precinct optica
70. esign and im plementation Chapter 9 describes a number of attack scenarios that demonstrate how the identified issues may be used in concert to subvert an election 5 1 Architectural Overview The election management system from Election Systems amp Software ES amp S prepares collects and tab ulates elections using either paper ballots or touchscreen terminals or a combination of both It contains software for managing all stages of an election as well as special hardware interfaces for configuring and retrieving results from the election devices The high level architecture of the ES amp S system is shown in Figure 5 1 Unity is the election management software suite It is comprised of a number of individual programs which interact with one another through shared data files collectively referred to as the database Elec tion Data Manager is used to initialize the database with jurisdiction voter and candidate information ES amp S Image Manager and iVotronic Image Manager are used to design the appearance of paper and touchscreen ballots The Election Reporting Manager is used to collect and tally election results and 31 County Ballot Election and Design Candidate Layout and Data Audio Hardware Programming Manager ES amp S iVotronic Image Manager Election Data Manager Removable Media Election Removable Results Media ji Election M100 M650 iVot Reporting Voting and Manager Tabulatio
71. ess Addition denial of service attacks can be performed on the audit data region of the card or on the card header section the region that defines the layout for the entire card It may even be possible to change vote data that is if the write that follows the altered pointer is done during poll closing The M100 could unintentionally write into the counter block region changed votes for particular races and subsequently stuff the ballot box 7 3 9 M100 accepts counterfeit ballots Description Portions of the paper ballots read by the M100 are printed using special inks whose reflection properties cause them to be ignored by the optical scanner To insure against counterfeit ballots specially designated areas of the ballot are printed using this special ink To detect counterfeit ballots the M100 checks for the presence of marks in these specially designated portions of the ballot Because photocopied ballots are printed using a single and detectable ink a normally copied ballot reproduces these marks The optical scanner detects no markings in these areas when legitimate ballots are used and perceives the marks if the ballot is a simple photocopy Visual inspection is sufficient to distinguish the two inks used to print the paper ballots By covering areas printed using the reflective ink it is possible to create duplicate ballots that are accepted by the M100 Al though ballots without the special portions may fail visual inspection if the
72. exploit them In the case of the iVotronic system voter access to the terminal is sufficient In the case of the Unity system brief access to any iVotronic or M100 optical scan results media returned back to the county for processing is sufficient As discussed in the Section 6 3 it is also possible to carry out the attacks against the Unity system by tampering with the firmware of precinct equipment 6 2 1 Unity The Unity election management system processes all precinct results and produces the tally reports that in most cases constitute the official tallies in races After polls are closed precinct counted ballot results are received into Unity through several different media including iVotronic PEBs iVotronic CF cards and M100 PCMCIA memory cards While Unity appears to correctly process properly formatted results from such media buffer overflows in Unity allow a maliciously altered iVotronic or M100 tally from a precinct to execute arbitrary software on the computer on which Unity runs to replace or alter the Unity software and to make arbitrary changes to the tally database and other election records There may be no indication to the operator that this is occurring and a system thus corrupted may continue to appear to operate normally when it is actually running software controlled by an attacker Because these attacks are carried out entirely through media routinely brought in to the county head quarters from precincts on election n
73. exploit this vulnerability he or she must have either a compromised the M100 optical scanner or b have access to the PCMCIA card that is used to transfer the data to the Unity back end system If the attacker wants to exploit this vulnerability using an exploit of an M100 optical scanner he or she must gain enough control over the M100 to be able to make it output arbitrary data This can be accomplished by loading modified firmware to the M100 For possibilities of loading new firmware to the M100 see Section 7 3 1 If the attacker has unmonitored access to the PCMCIA card when it has election results he or she can modify the data on this card since the integrity of the data that M100 saves on the PCMCIA card is not sufficiently protected see Section 7 1 4 A poll worker can carry out this attack in either of the two ways described above We have not fully implemented the attack thus we have not experimentally confirmed that the vulnerability is exploitable We have performed extensive code analysis as well as initial experiments towards performing the attack and everything we found indicates that this vulnerability is exploitable Impact This attack allows the attacker to run arbitrary code on the Unity server Therefore an attacker has the ability to gain full control of the machine running the server and could alter election results or compromise the Unity software He or she can then use the compromised software to spread the attack
74. f this virus 98 Unity Election Printed Election ia VVPAT Official Mgmt System Results Results Electi PEB Official Election Ballot Official 4 Definition j Virus Printed 1 Loop X VVPAT i 3 I Results Election Sais e xX Official i Ballot Definition Ballot l PEB Flash Definition t PCMCIA I 1 l 1 1 iVotronic i M100 1 ABE PEB Optical i Scanner i 1 I 1 Marked 7 Ballot Votes PEB Poll Ballot Worker Figure 9 1 ES amp S Architecture and Virus Loop Scenario unity 2 in Section 9 3 8 could also be used during the initial testing to modify the Unity code Again the modified code puts a virus on all of the PEBs that are distributed to all of the precincts These PEBs in turn spread the virus to all of the iVotronic DREs in all of the precincts The result is that every iVotronic now has the malicious code that compromises the election 9 4 Potential Attack Scenarios 9 4 1 Attack Scenario flash 3 iVotronic Exploits Using a Flash Card as Delivery Mecha nism Given more time we could modify the payload framework discussed in Section 9 1 1 to work with the Compact Flash code vulnerability discussed in Section 7 2 6 to deliver a payload similar to those discussed in Section 7 2 5 which used a PEB as the delivery mechanism This would give us an alternate path to introduce malicious code into the system if PEBs or PEB like clones were not av
75. ggering the image overflow vulnerability can cause the iVotronic to crash When the modified image was to be displayed the iVotronic crashed resulting in the expected denial of service 9 3 6 Attack Scenario flash 2 Voter Confusion In this scenario the 1Votronic machine is compromised in the same way as described for the flash 1 scenario That is a malicious flash card was crafted to take advantage of the flash card hot spot buffer overflow vulnerability discussed in Section 7 2 6 and the flash card was introduced into the system using one of the methods presented in that same section However for this attack code that uses the second code pattern described in Section 7 2 6 is exploited Recall that when executing this code an attacker can overwrite the stack return address with an address pointing to code of the attacker s choosing Therefore the possibilities for the attacker have no limitations To demonstrate how the election process could be subverted one of the system s election image files was replaced with a file that overflows an image hotspot handling function exploiting the second code pattern The exploit crafted on the image file triggered the image overflow vulnerability and introduced code that displays an obviously wrong message on the screen to confuse the voter Although displaying this message was basically benign it demonstrates that one could introduce code of their choice and could subvert an election For instan
76. i Votronic copies variable length strings from the PEB into memory allocated on the machine s stack If the PEB contains specially crafted large strings an exploitable buffer overflow occurs During our testing we confirmed that a specially crafted PEB or PEB emulator can exploit this buffer overflow to take complete control of the iVotronic Prerequisites The PEB or PEB emulator must contain a suitable malformed ballot definition Additionally the emulated PEB must have an EQC that matches that stored in the iVotronic Impact The buffer overflow allows an attacker to compromise an iVotronic terminal and take complete control over it Once compromised the following actions are available to the attacker e upload unauthorized and malicious firmware via either the PEB slot or the unprotected serial port see Section 7 2 14 e download current election results and or audit data via either the PEB slot or the serial port e modify or erase current election results and or audit data e print arbitrary text to the VVPAT including forged VVPAT ballots e modify or erase the contents of an inserted PEB or Compact Flash card e write random data to the firmware causing the iVotronic to become unusable until it can be disassem bled and reprogrammed 7 2 6 Buffer overflow in Hotspot image processing is exploitable Description The logic that reads image files from the Compact Flash card has an exploitable stack based buffer overf
77. ich forces the M100 to write to an invalid address This results in a segmentation fault The kernel intercepts the segmentation fault signal prints an error on the printer and freezes the M100 asking the user to reboot Our effort with this vulnerability was hampered by the fact that we did not have all of the source code for the M100 firmware even though we requested the missing firmware source numerous times As a result we wasted a lot of time and energy reverse engineering the firmware The result is that we did not have enough time to find a way to control what is written Therefore this scenario results in a system crash 9 3 11 Attack Scenario virus 1 Compromising Entire Election Process with a Virus The ES amp S voting process forms a loop That is the Unity election management system is used to initialize Personalized Electronic Ballots PEBs Compact Flash cards and PCMCIA cards These are in turn used to initialize the iVotronic DREs and the M100 optical scanners with ballot information The PEBs are also used to activate the DREs for voting power the machines on activate supervisor functions and to transport the election results from the iVotronics to Unity Figure 9 1 shows this flow of information Inserting malicious code at any step in this process could result in a virus spreading to all of the other components completely compromising the election This exploit uses the payload framework presented in Section 9 1 1 to impl
78. ies access to specific screen regions e g those corresponding to certain candidate selections Access to the screen calibration function of the iVotronic terminal requires the use of a supervisor PEB during power up e g after voting or at idle times No password is required Any supervisor PEB is sufficient for this purpose even one not specifically configured for the correct precinct or obtained from some other jurisdiction e g through secondary markets such as eBay A home made PEB emulator e g a specially programmed Palm Pilot and a small magnet is also sufficient The procedure requires about one minute and is from a distance largely indistinguishable from normal voter behavior A terminal can be maliciously re calibrated by a voter or poll worker to prevent voting for certain candidates or to cause voter input for one candidate to be recorded for another The terminal will remain in this state until the problem is detected e g through voter complaints and the terminal correctly re calibrated by poll workers which may require consultation with the central county office Voters may or 50 may not recognize that their votes are not correctly recorded depending on voter training and other factors While a maliciously calibrated terminal may be noticed by voters and can in principle be corrected in the field the attack is extremely simple for a poll worker or other person with access to a PEB to carry out and practical ev
79. ight an attacker need not have any physical access to the secure county facility in which Unity is located It is entirely sufficient for the attacker to have access to media such as PEBs or M100 memory cards returned to the county at the end of the election or to equipment such as iVotronics and M100s that write to such media Poll workers handle such media in the normal course of their duties and may have unsupervised access at various times of the day And as noted in the next section a voter using an iVotronic DRE may be able to circumvent the iVotronic terminal in a way that causes it to automatically produce such media when the polls close at the end of the day Note that because these vulnerabilities affect the central counting system a corrupted media attack conducted from any single precinct can corrupt results for the entire county We have successfully implemented PEB based attacks against Unity at the University of Pennsylvania and at WebWise and have confirmed that such attacks represent a readily exploitable threat in both iVotronic 53 and M100 based systems 6 2 2 iVotronic The iVotronic terminal firmware has several exploitable buffer overflow errors in its PEB input process ing functions These buffer overflows allow a PEB containing carefully structured data or an emulated PEB based on a palmtop computer to take control over the terminal The implications of attacks against iVotronics are discussed in Section 6 3 W
80. igned to a particular oval position on the ballot 7 4 3 M650 fails to validate variable length strings Description The M650 fails to check that constant sized buffers are sufficiently large to hold variable length strings A malicious ballot definition can define large strings that exceed the storage capacity of the allocated buffer In particular the M650 does not check that the length specified in the ballot definition for the election title does not exceed the number of bytes allocated for its buffer 2 By specifying a large election title a malicious ballot definition can overflow the allocated buffer and write arbitrary data to the M650 s memory Prerequisites To overflow the stack the attacker needs a Zip Disk containing a seemingly valid election definition that is one that conforms to the data structures defined in the M650 Functional Specification document The election definition obtained from a legitimate Zip Disk can be used as a template to construct a malicious election definition Impact Due to its location on the stack it does not appear that the stack overflow can be exploited to run arbitrary code on the M650 However it is likely that a malicious ballot definition can sufficiently corrupt 3 See Section 22 7 4 3 in the confidential annex 4Flection Systems and Software Inc Software Specifications Model 650 Central Count Ballot Tabulator version 2 0 0 0 as in n 22 80 the M650 to cause the m
81. il as official ballot in recount as in n 13 8Election Systems and Software Inc The iVotronic Voting System Operator s Manual version 9 1 January 2006 73 Figure 7 3 A VVPAT barcode encoding voter selections the document also warns that barcodes should not be used if prohibited by law Furthermore the counterargument that barcodes significantly improve tabulation efficiency and do not un dermine security since they can be verified by the accompanying text is fundamentally flawed Validating all barcodes requires processing all text portions of the ballot eliminating the efficiency advantage provided by the barcode Hence any speedup due to the barcode comes at the expense of failing to validate the voter verified portions of the audit trail If barcodes are not used they should not be included on VVPAT records The presence of barcodes may induce an election worker who is likely under substantial pressure to quickly tabulate election results to take the quick and easy path and utilize the barcodes Prerequisites Reading barcodes from a VVPAT printout requires a commodity 2D barcode reader Impact Election officials may tabulate votes using the barcodes printed on VVPAT records eliminating the safeguards offered by voter verified paper audit trails Ohio s recount procedures are vague on the question of permitted uses of barcodes during recounts An Ohio Secretary of State Directive stipulates that hand coun
82. ilable online from ES amp S for 5 00 each Scanner Key Part Number 75506 Ballot Box Key Part Number 75505 76 Prerequisites Access to either a scanner or ballot box key or both Impact A compromise of the ballot box key would grant the attacker access to the PCMCIA card slot and complete access to the ballots in the ballot box where an attacker could remove or add ballots A compromise of scanner key would give an attacker the ability to turn on and off the M100 A compromise of both keys would create a perfect scenario for an attacker to install malicious firmware The attacker would first need to compromise the ballot box key after which he can insert a malicious firmware PCMCIA card The attacker would then compromise the scanner key turning the machine off then on in order to reach the software installation menu Once in the software installation menu the attacker can install malicious firmware and finish the installation by again turning the machine off then on This could occur without detection Additionally the key blanks for a scanner and ballot box key are easily duplicated so a compromise of either key could affect machines nation wide 7 3 6 CRC routines used on the M100 are easily derivable Description CRC routines are used in many places by the M100 to verify the integrity of the data on the PCMCIA card An attacker can easily discover the constants used to generate the CRC alter the data on the PCMCIA card
83. inally provisioned This allows anyone with access to a card to add tally results for extra precincts which will be added to or supplant depending on the mode the Unity operator is using the true precinct results when read into the database 6 5 Procedural Mitigations We believe the issues reported in this study represent practical threats to ES amp S based elections as they are conducted in Ohio It may in some cases be possible to construct procedural safeguards that partially mitigate some of the individual vulnerabilities However taken as a whole the security failures in the ES amp S system are of a magnitude and depth that absent a substantial re engineering of the software itself renders procedural changes alone unlikely to meaningfully improve security Nevertheless we attempted to identify practical procedural safeguards that might substantially increase the security of the ES amp S system in practice We regret that we ultimately failed to find any such procedures that we could recommend with any degree of confidence A particular challenge in securing systems that use the iVotronic DRE terminal is the large number of precinct based attack vectors whose exploitation must be prevented Effective procedures that accomplish this even if they existed would be arduous indeed and would likely substantially hamper poll workers in their duties reduce the ability to serve voters efficiently and greatly increase the logistical challenges of
84. ion night results The mistake was noticed only when the report was regenerated without repeating the mistake several days later 8 2 Improper Message Passing In several instances Unity makes use of the Windows filesystem to communicate between components For example Unity components pass sensitive unencrypted information to other modules by writing the data to disk Such message passing techniques pose unnecessary security risks Unauthorized users with access to the filesystem can gain access to election keys and configurations bypassing Unity s authentication and authorization mechanisms many Unity applications require a valid username and password The ability to access sensitive files is increased when Windows filesharing is activated a scenario apparently realized in some counties in Ohio 3 Personal correspondence with Ohio Secretary of State Office employee November 28 2007 Election board verifies results Mount Vernon News November 29 2007 URL http www mountvernonnews com local 07 11 29 elc results html 85 Additionally message passing via files creates dangerous race conditions in which an attacker who has write access to the filesystem can modify files after they are created by one Unity component but before they are processed by another An attacker who can overwrite files can cause Unity to process arbitrary and incorrect election results As before this attack is worsened when Windows filesharing is empl
85. is more likely to be attributed to a screen miscalibration rather than to an attack If one assumes that many voters do not check that their vote was properly cast then this attack scenario can modify the results of an election and it cannot be detected by a manual audit The assumption that people do not check the paper trail is supported by at least two studies In Everett s thesis the author reports that over 60 of the voters she tested did not notice their votes had been changed in the review screen It is reasonable to expect that a similar result would be obtained by changing the vote on the paper record In another report Selker and Cohen present a study in which errors were intentionally inserted into the VVPAT No voters reported the errors during voting and only 8 agreed that there were errors in the VVPAT when asked 9 3 2 Attack Scenario peb 2 Changing a Careful Voter s Vote This scenario assumes that voters check their votes on both the screen and the printed ballot but that they are not familiar with all of the details of how their votes are recorded on the paper audit tape In this scenario the iVotronic machine is compromised in the same way as described for the peb 1 scenario However in this case the voting process proceeds normally That is the voters actual choices are displayed and printed as cast by the voter After the voter has completed all of his her votes the voter has to cast and confirm his her choices On
86. l Annex 63 cessing a M100 card the same card can be read in multiple times without warning the operator that such a thing has occurred There is graphical notification that could alert the operator about which results have been read in and from what precinct they came but there are no warnings that there were multiple reads of the same card It would also not be obvious that this has occurred However there are multiple modes for processing M100 cards add to mode and replace mode The difference between the two modes is that in replace mode if a precinct has already been read into the ERM then a warning is presented asking the operator if he or she really wants to replace the results for that precinct In add to mode this is not the case and all results are added together In large scale elections with multiple polling devices per precinct it is not clear whether the replace mode can be used because it would imply that there is only one data device for returning results per precinct With multiple polling devices per precinct this is not the case According to the documentation there appears to be no way to remove duplicated results once read into the ERM The only way to correct the mistake would be to zero the results and start from the beginning Impact Reading in results multiple times from a PCMCIA card would skew vote tallies and change the outcome of an election 7 1 11 Assumptions on the envi
87. l scan ballot counter 47 Vikant Corporation PCMCIA SRAM Card V insert This Way Figure 5 7 A PCMCIA SRAM flash card Figure 5 8 The ES amp S M650 centralized optical scan ballot counter 48 CHAPTER 6 ES amp S SYSTEMIC AND ARCHITECTURAL ISSUES We found fundamental security deficiencies throughout the ES amp S Unity EMS iVotronic DRE and M100 optical scanner software and hardware Virtually every mechanism for assuring the integrity of precinct re sults and for protecting the back end tallying system can be circumvented Election results can be tampered with in the ES amp S system by exploiting any of a number of different vulnerabilities we discovered The normal access provided to individual precinct poll workers and in some cases to voters themselves is suf ficient to conduct attacks that alter county wide election results and that in some cases cannot be detected or recovered from through audits or recounts Perhaps most seriously there is a strong potential for practical attacks that propagate virally from the field back to the county election management system That is a single circumvented piece of precinct hardware such as a memory card returned from a precinct for vote tallying can effectively take over the county wide back end tally system alter county wide results reported in the current election and then corrupt the installed firmware of additional precinct hardware in subsequent
88. le by reading the PEB Additionally by writing specially crafted blocks to the PEB an attacker can surreptitiously load exploit code that can compromise the backend Unity system when results are read from the altered PEB see Section 7 1 1 7 2 4 Emulated PEBs permit multiple votes Description A voter who can emulate a PEB by combining the attacks described in Sections 7 2 1 and 66 7 2 2 can use the PEB emulator e g a Palm Pilot to authorize multiple voter sessions Prerequisites To authorize a voter session the voter needs the correct election definition EQC and election key All three may be obtained by querying a PEB see Section 7 2 3 Impact Once a PEB has been read emulated PEBs can be used to authorize voting sessions in any iV otronic terminal that shares the same EQC election definition and election key as the cloned PEB Hence a malicious voter can repeatedly authorize himself and cast multiple votes Since the emulated PEB is ac cepted by all iVotronics with the same configuration a distributed version of this attack is possible Here pertinent data from a single cloned PEB is distributed to multiple attackers all of whom may cast multiple votes 7 2 5 Buffer overflow in poll opening process is exploitable Description The iVotronic does not verify that allocated memory buffers are sufficiently large to store variable length strings read from the possibly emulated PEB During the poll opening process the
89. like stealing votes or infecting PEBs inserted into the iVotronic with exploits An Example Malicious Payload Using the Framework One version of the payload intercepts control just before the vote summary page is displayed The payload steals votes at this point by changing them to select the attacker s candidate The voter could notice that the ballot has been modified and try to correct the mistake by recasting his her vote If this is the case the malicious firmware detects that the miscast vote has been discovered by intercepting the function that handles the pressing of the back button on this page That is if the vote changing is detected the malicious firmware stops stealing votes for a period of time so that it is less likely that someone will discover that something is going on The framework could also be modified to use a Compact Flash card as the delivery mechanism instead of a PEB 9 1 2 Pebserial a tool for reading and writing PEBs Pebserial is a program we developed to read and write PEBs using the serial interface Pebserial configures the serial interface in raw mode and implements the simple serial protocol used for communication between PEBs and ES amp S voting machines i e iVotronic and Unity Pebserial has the following functionality e it retrieves the PEB s Election Qualification Code EQC and general election information such as the PEB s type e g supervisor user serial number and version e it
90. ling the hardware components of the ES amp S system is somewhat misleading The code running on the iVotronic or Model 100 is in no way less susceptible to bugs tampering or co option than any other part of the Unity system When discussing the code comprising the ES amp S system we will use the term software to refer to code running both on desktop PCs and the specialized voting hardware 5 2 1 Unity Unity is the Windows based software suite for managing elections It contains tools for creating and man aging election databases Election Data Manager designing the appearance of ballots ES amp S and iVotronic Image Managers AutoMARK Information Management System tabulating and reporting results Election Reporting Manager Additionally there is a tool to audit the use of the other components of Unity Audit Manager and a tool for abstracting programming and communicating with the various hardware compo nents used by several Unity components Hardware Programming Manager The various components of Unity communicate with each other indirectly through common files stored on the Windows filesystem Election Data Manager The Unity Election Data Manager EDM is a Windows XP application which is used for creating and updating the election database used by the other software components of Unity The database for each county is stored in a single file in the Windows filesystem known as the Ballot Data File BDF Each BDF is logical
91. loit writer to pass the automatic test mode The manual test mode does utilize the GUI but a special variable in the iVotronic is set to indicate that test mode is running The exploit code can check this variable and whenever it is set the code can behave properly Prerequisites The malicious firmware needs to know what special variable to check to determine if it is in a logic and accuracy test or not Impact A malicious firmware can test the special variable and detect the current operating mode and perform different functions accordingly For example the malicious firmware could perform a correct count during the LAT procedure and then introduce errors during the actual voting procedure 7 3 M100 7 3 1 The M100 does not password protect the procedure for firmware uploads Description The procedure for uploading firmware to the M100 does not require a password If the PCM CIA card inserted into the M100 contains new firmware the M100 displays the install new software menu permitting anyone to install unverified firmware Prerequisites To install new firmware an attacker requires a properly formatted PCMCIA card and physical access to the M100 PCMCIA slot Impact The firmware on the M100 controls every procedure and operation of the M100 Therefore mali cious firmware would allow an attacker complete control of the machine Possible attacks include e altering vote totals e falsifying results tapes e altering menu displays
92. low These hotspot image files define areas on the screen that function as touchscreen buttons To support a variable number of hotspots the headers for such image files are variable length If the im age file specifies a larger than expected number of hotspots memory copied from the Compact Flash card overflows the allocated buffer See Section 22 7 2 5 in the confidential Annex See Section 22 7 2 6 in the confidential Annex 67 The iVotronic contains two independent code patterns for accessing hotspot images The first pattern which is used only in one location reads a fixed number of bytes from the image file into a local buffer of inad equate size The second pattern which occurs in ten different locations copies an unbounded number of bytes from the image file into a memory location on the stack Due to the manner in which variables are arranged on the stack the first code pattern allows an attacker to overwrite the called function s return address but not with data under his her control Therefore it cannot be used to execute malicious code However it can be used to crash the iVotronic causing denial of service In contrast the second pattern allows the attacker to execute arbitrary code Prerequisites To carry out the attack the attacker must write an appropriately crafted ballot header to the Compact Flash card There are a number of different methods an attacker might employ to introduce a malicious Compact Flash
93. ly made up of two different databases the County Database which contains tables of data which does not change from election to election and the Election Database which contains the data defining a single election Reusing the County Database from election to election is encouraged through an import feature which copies from a prior election s BDF to a new one and the initial County Database can be filled in from another county s BDF as well The remaining data entry is done either through the Windows GUI or by importing text files in a number of formats In addition to specifying the races candidates proposals and other data that will appear on the ballot for an election EDM is also used to select the equipment which will be used to cast votes in the election and specify any policies particular to the jurisdiction which influence ballot design e g candidate position rotation Finally centralized configuration of the iVotronic passwords see below is performed from within EDM Other modules of Unity read and parse the BDF directly as well as using Intermediate Interface Files IFF and Ballot Set Collection BSC files produced by EDM in a process referred to as merging the election database While the ballot data file is updated automatically when any changes are made in EDM the other files must be re generated by merging the election again 33 ES amp S Image Manager ES amp S Image Manager ESSIM is a C
94. maller PEB emulators is certainly possible Due to the PEB slot s location on the front of the iVotronic it is difficult for poll workers to monitor for potential PEB emulators without sacrificing voter privacy Prerequisites PEB emulators must be capable of communicating using ES amp S proprietary IR protocol This protocol is simple consisting primarily of send block and receive block commands and can be easily understood by probing a legitimate PEB 65 Figure 7 1 A PEB emulator running on a Palm Pilot simulates an initialization PEB during an open election resetting all terminal passwords to EVEREST Impact The ability to emulate a PEB enables a wide range of serious poll worker and voter attacks Attacks involving PEB emulation are described in Sections 7 2 4 7 2 5 7 2 8 7 2 9 7 2 10 7 2 11 7 2 12 and 7 2 13 7 2 3 PEB Emulators can read and or write arbitrary data on a PEB Description A PEB emulator can read and or write arbitrary data on a PEB placed in close proximity Prerequisites Since PEBs are activated by detecting the presence of a magnet the PEB emulator must be placed in close proximity when reading or writing to the PEB Malicious voters may have sufficient access to the PEB when signing in if the poll worker leaves the PEB on the voter sign in table Impact As described in Section 7 2 1 the EQC election encryption key election definitions and any stored election results are easily discernib
95. management functions This confluence of vulnerabilities creates a closed loop for viral propagation into every part of the ES amp S system through the compromise of a single system component For example a voter can compromise an iVotronic terminal though its PEB slot The iVotronic then may be programmed to create results media at the end of the election day that in turn corrupts the software of the central Unity system The compromised Unity system in turn may be programmed to load corrupted firmware into all M100s and iVotronics in the county when provisioning a subsequent election At this point every major component of the system is running compromised code which originated with a single attacker with only voter access in a single precinct Needless to say such an attack represents a grave threat to the integrity of the elections of any jurisdiction to which this happens 6 4 Ineffective Cryptography and Data Authentication Much of the critical election data in the ES amp S system ballot definitions precinct vote tallies and so on are communicated between the central county headquarters and precincts through small removable storage media In iVotronic DRE based systems the primary media are PEBs and in some cases CF memory cards In M100 based precinct counted optical scan systems the primary media are PCMCIA memory cards These media share two important characteristics that make them attractive targets for attack
96. mpered with in the field Virtually every piece of critical data at a precinct including precinct vote tallies equipment configuration and equipment firmware can be com promised through exposed interfaces without knowledge of passwords and without the use of any specialized proprietary hardware e Failure to effectively control access to election operations Access to administrative and voter func tions are protected with ineffective security mechanisms For example undocumented quality assur ance hardware tokens that bypass password checks are easily forged using inexpensive commodity devices such as palmtop computers Central back end election management software is vulnerable to attacks that exploit coding and design errors and that can be triggered from data sent from the field e Failure to correctly implement security mechanisms Many of the most serious vulnerabilities in the ES amp S system arise from the incorrect use of security technologies such as cryptography This effectively neutralizes several basic security features exposing the system and its data to misuse or manipulation e Failure to follow standard software and security engineering practices A root cause of the security and reliability issues present in the system is the visible lack of sound software and security engi neering practices Examples of poor or unsafe coding practices unclear or undefined security goals technology misuse and poor mainte
97. n Figure 5 1 The high level overview of the ES amp S Unity voting system with user input to each stage of the election Audit Manager is used to verify election results using audit data All interaction between Unity and voting hardware is controlled by the Hardware Programming Manager program The iVotronic is a touchscreen direct recording electronic voting terminal DRE There are two distinct types of iVotronic terminals distinguished by colored inserts along the sides red supervisor terminals and blue voter terminals Both types of iVotronic terminals are activated using special hardware tokens called Personalized Electronic Ballots PEBs which are also used to store ballot definitions and election results PEBs are typically programmed via a supervisor terminal at the start of an election and read using either a supervisor terminal or a dedicated PEB Reader connected to the machine running the Election Reporting Manager at the end of an election A PEB can be used in multiple iVotronics as long as they are qualified for the same election and polling place The voter iVotronics also use Compact Flash cards to store large ballots audio ballots and election result audit files Connected to the iVotronic in Ohio is a printer which provides a voter verified paper audit trail known as the Real Time Audit Log printer in ES amp S documentation and source code A separate Communication Pack is connected to iVotronic terminals at the start and
98. n obtained from a legitimate Zip Disk can be used as a template to construct a malicious election definition Impact Under some circumstances the heap overflow may be exploited to inject code that will take control of the M650 7 4 5 M650 accepts counterfeit ballots Description Portions of the paper ballots read by the M650 are printed using special inks whose reflection properties cause them to be ignored by the optical scanner To ensure against counterfeit ballots specially designated areas of the ballot are printed using this special ink To detect counterfeit ballots the M650 checks for the presence of marks in these specially designated portions of the ballot Because photocopied ballots are printed using a single and detectable ink a normally copied ballot reproduces these marks The optical scanner detects no markings in these areas when legitimate ballots are used and perceives the marks if the ballot is a simple photocopy Visual inspection is sufficient to distinguish the two inks used to print the paper ballots By covering areas printed using the IR reflective non read ink it is possible to create duplicate ballots that are accepted by the M650 Although these ballots may fail visual inspection if they are ever questioned since the portions printed using the reflective ink are absent better forgeries can be constructed by obtaining IR reflective non read ink Such ink is available for general purchase at online vendors or can
99. nance are pervasive This general lack of quality leads to a buggy unstable and exploitable system 29 We believe the issues reported in this study represent practical threats to ES amp S based elections as they are conducted in Ohio It may in some cases be possible to construct procedural safeguards that partially mitigate some of the individual vulnerabilities reported here However taken as a whole the security failures in the ES amp S system are of a magnitude and depth that absent a substantial re engineering of the software itself renders procedural changes alone unlikely to meaningfully improve security Nevertheless we attempted to identify practical procedural safeguards that might substantially increase the security of the ES amp S system in practice We regret that we ultimately failed to find any such procedures that we could recommend with any degree of confidence A particular challenge in securing the iVotronic DRE terminal is the large number of precinct based attack vectors whose exploitation must be prevented Effective procedures that accomplish this even if they existed would be arduous indeed and would likely substantially hamper poll workers in their duties reduce the ability to serve voters efficiently and greatly increase the logistical challenges of running an election The security failings of the ES amp S system are severe and pervasive There are exploitable weaknesses in virtually every election device and softw
100. nclear what should be done If the compromised equipment is used fraudulent votes may be counted If it is not used previously cast legitimate votes may be lost making breaking a seal a simple way for an attacker to destroy votes 6 2 Critical Errors in Input Processing At least two critical components of the ES amp S system suffer from exploitable errors in functions that process input over their external interfaces Both the Unity tallying system and the iVotronic terminal have buffer overflow software bugs that allow an attacker who can provide input e g on a PEB or memory card to effectively take control over the system A buffer overflow in input processing is common type of program ming error one that has been responsible for many security failures in modern computing Avoiding buffer overflows in input processing is regarded as one of the most basic defenses a system must have We found numerous buffer overflows throughout the ES amp S system Several of these buffer overflows in the Unity tallying software and in the iVotronic terminal firmware have extremely serious practical security implications An attacker who can present input to any these systems on an iVotronic PEB or on an M100 memory card from a precinct can exercise complete control over the results reported by the entire county election system Most seriously the nature of these vulnerabilities means that there are few barriers to obtaining the access required to
101. nd execute arbitrary code on the supervisor terminal Prerequisites To exploit the buffer overflow an attacker needs to either compromise the Unity backend system or connect the supervisor terminal to a device via its serial port that mimics Unity Impact Since the supervisor terminal is responsible for configuring PEBs for an election a compromised iVotronic supervisor terminal can write malicious data to the PEBs in order to exploit vulnerabilities in iVotronic voter terminals e g by exploiting the vulnerability described in Section 7 2 5 See Section 22 7 2 7 in the confidential Annex 68 7 2 8 Service Menu Mode in iVotronic does not require properly configured PEB Description By pressing the VOTE button and inserting a PEB the iVotronic enters a service menu mode which allows various configuration and election settings to be viewed and or modified In our tests we found that few checks are carried out to determine whether the inserted PEB is properly qualified Consequently any PEB even one not configured for the current election can be used to enter the service menu mode Prerequisites Most service menu items require the user to enter a password The iVotronic defaults to specific passwords unless they have been explicitly changed Note that password checks are bypassed when a possibly emulated Factory QA test PEB is inserted see Section 7 2 10 Impact Anyone with an unqualified PEB or a device that acts like one
102. nderstood by probing a legitimate PEB Impact Factory QA PEBs are presumably used for testing iVotronics as part of internal quality assurance testing They function exactly like any other PEB except that they bypass all password checks in all iV otronic menus Debug PEBs allow any voter or poll worker to access important service menu items see Section 7 2 8 on the iVotronic without the knowledge of any passwords or other election specific secrets Further details of various attacks using emulated Factory QA PEBs are described in Sections 7 2 11 7 2 12 7 2 13 and 7 2 14 7 2 11 Emulated Factory QA PEB can clear a terminal erasing all vote and audit data Description A possibly emulated Factory QA PEB can be used to initiate the iVotronic s clear and test procedure causing all vote data and audit logs to be deleted from the iVotronic flash memory Clearing a terminal takes less than a minute and can be done surreptitiously by a malicious voter with a Factory QA PEB or PEB emulator Prerequisites If an election has already been loaded on the iVotronic an Initialization PEB or emulator first needs to be used to perform terminal initialization see Section 7 2 9 The initialization process closes the open election and enables the Clear and Test Terminal option in the iVotronic services menu No election specific secrets are required Impact Using a possibly emulated Factory QA PEB a malicious poll worker or stealthy voter c
103. ns on an off the shelf version of the Microsoft Windows operating system This plat form is very heavily dependent on many aspects of the local computing environment for its security When used in a networked environment even behind a network firewall there are many potential vulnerabilities that can be mitigated only through careful expert system management Unfortunately the precise requirements for using Unity in a networked Windows environment are not specified by ES amp S and appear to be left to individual counties to manage without specific guidance An analysis of these issues is beyond the scope of this report but we caution that there are many potential problems that could arise from the various ways in which the Unity system s Windows platforms might be managed some of them quite subtle 6 3 3 M100 firmware Firmware can be loaded into the M100 optical scan ballot counter by placing a specially structured file on its PCMCIA card which is also used during polling for ballot definitions and other precinct parameters If new firmware is present on the card when the M100 is turned on there is a brief screen prompt and the new firmware is loaded No password is required Any poll worker or other person with access to the PCMCIA card slot can thus easily load new firmware This slot may be protected by a tamper seal in some jurisdictions but the seal may be able to be bypassed because of the design of the cover mechanism Because th
104. ntly by their PEB Kind both read only values once the PIC inside is burned The two documented PEB Kinds are supervisor and voter which are visually differentiated by a red and blue band in the casing In Ohio only supervisor PEBs are used in the documented election procedures There is a third undocumented PEB Kind recognized in the iVotronic source code The first block of a Supervisor PEB further identifies it as having been configured as a regular Supervisor PEB or as a special purpose Supervisor PEB which can perform a single iVotronic administrative function without needing to go through multiple menus These special purpose PEBs are commonly referred to by the name of the function they access e g a Clear and Test PEB jumps immediately to the Clear and Test menu of the iVotronic it is inserted in In a regular Supervisor PEB the remaining blocks hold the ballot identical to the bin or ebn produced in HPM followed by a fixed size vote results structure the vot file read by ERM and finally the remainder of the PEB except for the last block holds write in ballots The last block of the PEB is known as the Election Qualification Code block and serves to authenticate the PEB to the iVotronic 5 2 5 PEB Reader The PEB Reader is a standalone cradle used by devices with standard RS232 serial ports to communicate with PEBs It acts as a media converter between the RS232 serial connection and the IrDA connection to the PEB
105. o non default values or values that cannot be entered using the on screen keyboard the attack makes it difficult to restore the terminal to a usable state until another initialization PEB is used to reset the passwords 7 2 10 Emulated Factory QA PEBs bypass all password checks Description The iVotronic system contains a backdoor that bypasses all passwords when a Factory QA PEB also called a Debug PEB is inserted into the iVotronic A Factory QA PEB is a special PEB that See Section 22 7 2 10 in the confidential Annex 69 follows the same protocols as a standard PEB When a PEB is inserted into the iVotronic the iVotronic polls the PEB for its type If the type corresponds to a Factory QA PEB the iVotronic enters a state in which all password prompts are automatically bypassed Emulating a Debug PEB is as easy as emulating a standard PEB see Section 7 2 2 All PEBs supervisor voter and debug have exactly the same hardware and use the same protocol to interact with the iVotronic terminal Debug PEBs differ only in the PEB type identifier they report to the iVotronic Consequently a PEB emulator can easily identify itself as a debug PEB Prerequisites The debug PEB can be emulated using any device with an IR port e g Palm Pilot The emulator must be capable of communicating using ES amp S proprietary IR protocol This protocol is simple consisting primarily of send block and receive block commands and can be easily u
106. ointers point to any location in memory Furthermore because the code then writes to some of the pointed structures it is possible to override any sequence of 4 bytes in memory 77 Note Our effort with this vulnerability was hampered by the fact that we did not have all of the source code for the M100 firmware We requested the missing firmware source numerous times but it was never delivered As a result we spent a lot of time and energy reverse engineering the firmware This is of particularly concern because it indicates that the M100 contains firmware that is not contained in the firmware provided to the Independent Test Authorities ITA The extra firmware is usually not updated and seems to be the kernel of the operating system running on the scanner QNX Although the kernel is developed by a third party and could be considered a COTS component it has to be configured with the appropriate hardware drivers etc in order to be used with a particular kind of hardware Since this configuration would be specific to the M100 it should not be considered COTS Prerequisites The attacker needs a way to craft a special PCMCIA card and needs access to the M100 Sections 7 3 6 through 7 3 7 discuss the details of the prerequisites for this vulnerability Impact A number of different attacks can result from this vulnerability Perhaps the most prevalent is the ability to perform a denial of service that could disrupt the ballot counting proc
107. omized according to a uniform probability distribution that is each audit record in the audit log should have equal probability of corresponding to a particular voter record The iVotronic uses a weak randomization procedure that results in a partial ordering of voter selections When a voter casts a ballot the voter s selections are uniformly at random assigned to one of approximately thirty sectors in the iVotronic s internal flash memory The voter selection is appended to the first available location in the chosen sector if the sector is full a new sector is random selected Consequently each sector contains a sequential ordering of voter selection images Prerequisites Access to audit information is required Impact An election official with access to audit information may ascertain a partial ordering of voter selections Such information may reveal voter trends throughout the election 7 2 16 VVPAT barcodes contain timestamps Description After a voter casts a ballot a barcode containing the current time is printed to the VVPAT printer gt These timestamps can be used to reconstruct the ordering of votes even if VVPAT records are detached from the roll to mask vote order and protect voter privacy after the close of the election Prerequisites Access to VVPAT records is required Impact An attacker can reconstruct the order of VVPAT printouts using the timestamp encoded in the barcodes revealing voter trends
108. or the iVotronic the Compact Flash folder produced by iVIM is copied using a helper application Before the PEB can be programmed a binary ballot file is created using another helper applica tion This file can either be encrypted or unencrypted depending on options set by the user The PEB is then programmed using another command line tool which copies this binary ballot file along with the EQC block to a unused Supervisor PEB see Section 5 2 4 A red Supervisor iVotronic is connected to the computer running HPM over a serial port and used to communicate with the PEB for this programming 34 Election Reporting Manager The Election Reporting Manager ERM is used to collect and report results from an election Like HPM it is a COBOL Windows program which relies on several helper applications and libraries written in other programming languages to access the removable media containing votes It uses the same directory of data files generated by HPM upon importing an IFC file and creates a new election database file used to store results Election results are collected from M100 and M650 scanners directly using an external PCMCIA card reader and Zip drive iVotronic results can be collected either from the Compact Flash card of each machine or from the Master PEB used to close several iVotronics The CF card is read directly using a USB card reader while the Master PEB can be read using either a Supervisor iVotronic or PEB Reader connected to th
109. oyed Rather than use files to communicate data good software engineering practice utilizes operating system features to more securely and reliably share information Microsoft Windows provides such interprocess communication mechanisms in the form of COM objects pipes and sockets 8 3 Static Code Analysis It is customary for large and complex software systems particularly those that operate in security centric domains to undergo rigorous internal quality assurance testing As part of the QA process static code analysis tools software that searches the source code for bugs and potential security vulnerabilities help software manufactures catch potential weaknesses before the product is released and used Our analysis of the quality of the source code indicates that an acceptable level of static code analysis was never performed During our review we found several notable programming errors all of which were detected using readily available source code analysis tools and techniques e Using the Microsoft Visual Studio 2005 compiler a more recent version of the compiler than that used by ES amp S we discovered that compilation failed due to several serious programming errors For example integers declared in for loops were used in out of scope contexts This constitutes a violation of the ANSI C standard and results in compile time errors under most C compilers with which we are familiar The compiler used by ES amp S Mic
110. pens only after the voter has confirmed his her selection By doing this the modified selection is never shown on the screen and is printed on the audit log only when the paper is scrolling up immediately before the barcode is printed 9 3 3 Attack Scenario peb 3 Canceling the Vote of a Fleeing Voter In this scenario the iVotronic machine is compromised in the same way as described for the peb 1 scenario However this time the malicious firmware takes advantage of fleeing voters These are voters that leave the voting station before having completed their voting which is not uncommon In Ohio the votes of fleeing voters are discarded When a voter flees the iVotronic makes a chirping sound after about twenty seconds which alerts a poll worker The poll worker has to insert a supervisor PEB in the iVotronic and follow a specific procedure to discard the ballot For privacy reasons the poll worker has no access to the content of the ballot For this scenario the malicious firmware intercepts the call to the routine that enables the chirping sound indicating a fleeing voter The malicious firmware behaves differently depending on whether or not the fleeing voter cast a vote for the attacker s candidate Case 1 Voter voted against the attacker s candidate If the fleeing voter did not vote for the attacker s candidate then the malicious firmware does nothing and lets the chirping program perform as it should In this case the
111. r output files Hardware Programming Manager Hardware Programming Manager HPM is used to transfer ballot configurations from files produced by ESSIM and iVIM to the removable media used in the M100 M650 and i1Votronic It consists of a Windows application written in COBOL and a number of helper applications and shared libraries DLLs written in C and C The COBOL code focuses on overall program logic and the creation of a new election database while the C and C code focuses on communicating with the PEB and memory card readers and performing specialized operations e g cryptography Additionally HPM serves as the bridge between the Election Data Manager where elections are defined and the Election Reporting Manager where elections are tallied and reported since the latter is also a COBOL based application The election configuration in HPM is imported from the IFC file produced by ESSIM Adjustments to the election database can be made within HPM prior to writing the removable media to be used in the iVotronic or ballot scanner These changes are only seen within HPM and the Election Reporting Manager and not reflected in EDM If changes are made in EDM they must be propagated through ESSIM to HPM and be imported again Finally device specific settings for the M100 and M650 optical scanners can also be made from within HPM HPM copies files from ESSIM directly to the PCMCIA SRAM cards and Zip disks for the M100 and M650 scanners F
112. re two studies however that should be mentioned In December 2006 a team led by Florida State University s FSU Security and Assurance in Information Technology SAIT Laboratory was commissioned to conduct a static software analysis on the iVotronic s version 8 0 1 2 firmware source code The intent was to determine and identify flaws vulnerabilities or anomalies if any that may have caused or contributed to the higher than expected under vote rate in the District 13 Race between candidates Vern Buchanan and Christine Jennings The second study was carried out by two Ohio privacy activists James Moyer and Jim Cropcho They demonstrated how the time stamped paper trails produced by the iVotronics could be combined with a list of voters in the order they voted to determine which voter voted and in which way Since Ohio law permits anyone to request and obtain these two documents this is a clear violation of the secrecy of personal ballots We did not attempt to reproduce the findings of either of these groups To carry out the red team experiments we crafted special tools that are designed to obtain information about an election and to circumvent the operations of an election We also performed a number of physical attacks that enabled us to use the equipment in ways that allowed us to alter or thwart an election The first section of this chapter presents some of the special purpose tools that we developed Next the security seals and phy
113. rerequisites This attack requires access to a PEB and the facilities to write data to the PEB such as our pebserial tool The PEB must be read using the PEB reader 59 Impact Since the attack enables arbitrary code execution on the Unity server an attacker has the ability to gain full control of the machine running the server Therefore the attacker could perform activities such as installing a virus or trojan that could then be used to change the election results and spread the virus to other ES amp S components e g the 1Votronic or M100 machines Scenario unity 2 in Section 9 3 2 demonstrates an attack using this vulnerability 7 1 2 Data from M100 can cause a buffer overflow in Unity Description Data from the M100 optical scanner can cause a buffer overflow in Unity The data which includes election results and audit data are stored and transferred on a PCMCIA card The ERM module of Unity expects a fixed maximum number of precincts to be reported on a given PCMCIA card This number is hardcoded in the source code of the program However the actual number of precincts is read from the PCMCIA card and the attacker can thus set it arbitrarily high within limits of the integer datatype used To exploit this vulnerability an attacker can create a specially prepared PCMCIA card that will allow the execution of arbitrary code The attacker can gain full control of the Unity server in this manner Prerequisites If an attacker is to
114. res only the use of a readily available Torx security screwdriver Once the housing has been removed the internal flash chip can be removed from its socket reprogrammed with a standard flash writer and replaced Note that while surreptitious terminal disassembly is unlikely to be possible in an active polling place it may be an attractive option for an attacker who enjoys unsupervised access to stored terminals e g the night before an election Via the firmware update menu This is the most direct attack against firmware As discussed above a palmtop computer and a magnet can be used to emulate a QA PEB and bypass the password check If the polls are open they can be closed by using a an emulated QA PEB to clear the terminal first Note that with this approach the firmware must be loaded though the external CF card interface which might be protected with a tamper evident seal although that seal can be bypassed by removing the housing Via the PEB interface during the polling day This is perhaps the most serious practical threat to the iVotronic firmware As discussed in Section 6 2 errors in the iVotronic s PEB input processing code allow anyone with access to the PEB slot on the face of the terminal including a voter to load malicious software that takes complete control over the iVotronic s processor Once loaded this software can alter the terminal firmware change recorded votes mis record future votes and so on throughout th
115. revent an attacker to change the data on the card in such a way that the data pass the CRC checks An attacker can therefore easily modify delete or add data to the correct results that are stored on the card This greatly facilitates the attacks described in Sections 7 1 2 and 7 1 3 Prerequisites An attacker needs to have access to the card when the data election results and audit data are being transferred to Unity Impact If the attacker has access to the card when it is transferred to Unity he or she can arbitrarily modify the data on the card Thus the attacker will have complete control over the results coming from the precinct s on the card He or she can also attempt to overtake the Unity back end system see Section 7 1 2 or change the vote totals for other precincts see Section 7 1 3 7 1 5 Processing audit data can cause a buffer overflow of a global variable Description Audit data uploaded to Unity can cause a buffer overflow of a global variable The ERM module uses a buffer with a fixed amount of allocated memory to input a string with a variable length The See Section 22 7 1 5 in the confidential Annex 61 attacker can prepare the input to be longer than the pre allocated buffer The audit data enter the system via a PEB or a CF card prepared by the iVotronic The buffer in question is a global variable thus is not allocated on the stack and the number of bytes by which the attacker can overflow the buffer i
116. ronment for Unity are unspecified Description The assumptions for the environment in which Unity is running are left unspecified This includes the configuration of the operating system Microsoft Windows networking environment services running on the computer etc Thus it is not clear what are the security guarantees that Unity expects from the host system It is possible to assume that Unity will be run in a relatively isolated environment in county election head quarters and is used only by trusted staff However even in this case many issues need to be carefully considered including network setup possible interference with other processes running on the machine updates and patches to the operating system and removable media that are read by the machine A concrete example is that autorun should be disabled for all removable media drives If it is not the case the program run by autorun may compromise the host machine The assumptions on the security of the host system are not specified by the vendor Instructions for the operators for setting up and managing the server on which Unity is running are also not provided Impact Many potential platform security issues may be present in any county Unity installation Enumer ating all issues caused by the host system and resulting attacks is beyond the scope of this study 7 1 12 iVotronic Image Manager bundled with vulnerable Java Runtime Environment Description The Windows
117. rosoft Visual Studio 6 optionally allows such unorthodox C code presumably by inferring correct addresses for out of scope variables Additionally we discovered at least one instance when a C function call that takes no arguments was invoked without the required parentheses Under most C compilers including later versions of Visual Studio such references to function names resolve to the address of the function and when invoked in a standalone fashion result in compile time errors Oddly such programming practices are accepted under older versions of Microsoft s compiler Arguably these programming practices do not constitute errors since they are accepted by the com piler However incorrect function invocation and the use of out of scope variables is a dangerous practice In both cases the C compiler must infer the programmer s intent e g the scope of the variable or that the function reference should be treated as a function invocation An incorrect con clusion could produce undesirable behavior Additionally if in the future the code is compiled using a different and more standards compliant compiler including more recent versions of Microsoft s C compiler the best case scenario results in compilation errors At worst the nonstandard pro gramming practices could result in unstable and unpredictable behavior e The ES amp S source code makes extensive use of memory unsafe string operations In particular the str
118. rt located on daughter cards which are not accessible from outside the locked chassis 5 2 11 Zip Disks The M650 uses FAT32 formatted 100MB Zip disks to load ballot configurations and store tallies of counted ballots The files on the disk are copied by the Hardware Programming Manager In Windows these disks are mounted to the desktop and accessible to any Windows application with no special libraries 5 2 12 AutoMARK Voter Assist Terminal The AutoMARK Voter Assist Terminal VAT is a combination scanner printer used by the voter to mark and verify optical scan ballots to be tabulated by the M100 or M650 It is intended to be used by disabled voters as required by the Help America Vote Act The VAT runs Windows CE now called Windows Mobile with a custom application developed in Net for the interface The VAT is operated by inserting a paper ballot which is then scanned and matched to a pre defined ballot style configured during election setup Translations into various languages as well as audio ballots may be configured for a particular ballot style which the user then uses to complete or verify their ballot Once the user confirms their choices an inkjet print head contained within the VAT marks the inserted ballot if it was initially blank and returns it to the voter There is a single Compact Flash slot used to program ballot styles and several jacks for audio headsets and input devices The AutoMARK does not store or tabulate votes it
119. s More thorough testing and analyses are required to find bugs missed by automated tools and to rule out false positives In our testing Fortify SCA reported hundreds of hot those deemed most likely to be correctly diagnosed and potentially exploitable buffer overflows in Unity s source code To a lesser extent Fortify SCA also noted many other types of security problems including string format vulnerabilities integer overflows and the use of non null terminated strings in C and C a special character called the null character is used to denote the end of a string Some of the reported errors are likely false positives i e they refer to correct code and many of the diagnosed problems cannot necessarily be exploited by an attacker to gain control of the system However the discovery of so many potential vulnerabilities implies that serious security and reliability problems likely do exist a conclusion we repeatedly confirm see Chapter 7 and arguably equally troublesome indicate that the vendor did not sufficiently validate their code 5 Fortify Source Code Analysis SCA URL http www fortifysoftware com products sca 87 88 CHAPTER 9 ES amp S EXAMPLE ATTACK SCENARIOS This chapter reports on the red teaming exercises performed to evaluate the ES amp S Voting System Prior to the study reported here the ES amp S system had not received a detailed source code and red teaming security review There we
120. s firmware behaves normally during the pre election but it starts to actively modify the election results as soon as the actual election starts The malicious firmware uses the LAT detection vulnerability discussed in Section 7 2 18 to determine whether the iVotronic is in election mode The malicious firmware monitors the votes being cast and modifies the ballot to give advantage to a certain candidate The firmware uses the payload hooks and links in just before the vote summary page is dis played It steals votes at this point by assigning them to the other candidate The modified vote shows up on both the screen and the Real Time Audit Log RTAL If the voter actually checks the printed output of his her votes and discovers that an error has been made the malicious firmware detects that the voter recasts his her vote because the firmware is also hooked into the back button on this page which is used to recast a vote That is if the voter detects the modified vote the malicious firmware allows the voter s corrected vote to be recast and stops stealing votes for a period of time In this way it is less likely that someone will discover that something suspicious is going on It is worth noting that both the summary page and the paper trail report the modified selection rather than the original one From an attacker s perspective it is better to keep the screen and paper consistent because if an abnormality is detected then it
121. s are functionally identical The same firmware is used on both Supervisor and Voter iVotronics with a serial number check at boot to determine which mode is used In the next two subsections the unique aspects of each type are introduced iVotronic Supervisor Terminal The red Supervisor Terminal is used to manage PEBs and the contents of their flash memory before during and after elections It plays a far more significant role in the Voter Activated Voting mode which is not used in Ohio elections where at least one Supervisor Terminal must be at every polling place In the Poll Worker Activated Voting mode used in Ohio a Master PEB for each polling location is created from HPM using a Supervisor Terminal connected via null modem cable Afterwards each Master PEB is then cloned several times using a Supervisor Terminal standalone from Unity in order to produce the Supervisor PEBs needed while the polls are open see Section 5 3 At this point the supervisor terminal is no longer required for opening closing or tallying the election iVotronic Voter Terminal The blue Voter Terminal is the iVotronic used by voters to cast their ballot When a qualified Supervisor PEB is inserted the iVotronic prompts the poll worker to select the correct ballot to be voted on The poll worker then removes the PEB and leaves the voter to make their decisions Once the voter casts their ballot the Voter Terminal goes into a low power state and waits for the
122. s from all of the precincts The most common method of delivering the results is on a results PEB Unfortunately the Election Reporting Manager ERM component of Unity which is used to compile the results has a buffer overflow in the code that reads the results PEB For this scenario a malicious PEB is crafted to take advantage of the ERM PEB reader buffer overflow which was presented in Section 7 1 1 The malicious PEB is introduced into the system using one of the methods presented in Section 7 2 5 The malicious code on the PEB creates an account attacker with password weownyou When the PEB is read by the ERM using the PEB reader the data on the PEB overflows the stack of the ERM application The return address of the current function is overwritten to point to malicious code which is then executed The malicious code adds the attacker account and control is returned to the application which after a few seconds delay displays a message indicating that reading the PEB has failed This is expected since the malicious code in its current form does not take care to exit cleanly after it is executed The success of the attack is verified by logging in to the system as user attacker with password we ownyou The login was successful 9 3 9 Attack Scenario m100 1 Changing the Firmware on the M100 Scanner The M100 optical scanner is used to count physical election ballots The firmware on the M100 is updated by
123. s limited Therefore the attacker might not be able to use this vulnerability to execute arbitrary code on the server running Unity Prerequisites If an attacker is to exploit this vulnerability he or she must have either compromised the device that put the data to the PEB or the CF card the iVotronic or have access to the PEB or the CF card that is used to transfer the data to the Unity back end system Impact The attacker can corrupt the memory of the ERM module i e change the value of some data or influence the control flow In the event that the memory layout is favorable to the attacker he or she might be able to realize more severe attacks As explained above this attack involves a global variable therefore the attacker is not guaranteed to be able to overtake the machine running Unity 7 1 6 Unity decrypts a PEB using the EQC from the PEB Description Unity uses the Election Qualification Code stored on the PEB to decrypt the encryption key stored on the PEB If Unity used the original EQC that was used for qualifying the other election equipment and compared it with the EQC on the incoming PEB it would ensure that the data is coming from a properly qualified 1Votronic However this is not the case Unity reads the EQC from a PEB then verifies the EQC and key data with a CRC and finally uses the EQC value to decrypt the encryption key which is subsequently used to decrypt the data on the PEB The only protection is thus the
124. s possible to network the M650 and to have the results transferred by network instead of by Zip disk 5 4 Software Versions The source code analysis and red teams were provided with the following versions of the Unity environment and source code by the vendor 42 Component Application Version Unity 3 0 1 1 Audit Manager 7 3 0 0 Election Definition Manager 7 4 4 0 Election Reporting Manager 7 1 2 1 Hardware Program Manager 5 2 4 0 Data Acquisition Manager 6 0 0 0 ESS Image Manager 7 4 2 0 iVotronic Image Manager 2 0 1 0 iVotronic Firmware 9 1 6 2 9 1 6 4 M100 Firmware 5 2 1 0 M650 Firmware 2 1 0 0 RMCOBOL RT 7 5 01 COBOL WOW RT 3 12 Source Component Version Source Component Version Source Component Version 4 Key Sound Pic 1 0 0 0 Events 9 1 1 0 REGUTIL 1 0 0 0 AuditManager 7 3 0 0 EXITWIN 1 0 0 0 SCNDAT30 3 0 1 0 BXP_Gen 1 0 0 0 GENPARMS 1 3 0 0 Serve650 1 0 0 0 CB_650 1 0 0 0 GetAuditData 9 1 0 0 SHELL 1 0 0 0 CB_EMP 1 0 1 0 Images 9 1 2 0 SHELLSETUP 1 0 0 0 CB_M100 1 2 0 0 Init650 2 1 0 0 TGEN30 3 0 1 0 CB Duplicator 9 1 0 0 iVOTIM 2 0 1 0 Undrvote 9 1 2 0 CF_Utility 9 1 0 0 iVotronic 9 1 6 2 Viodialog 9 1 2 0 9 1 6 4 CRCDLL 1 4 0 0 Loader ILD 9 0 0 0 VIOWIN 9 0 0 0 EDM 7 4 4 0 M100 5 2 1 0 Volume Control 1 0 0 0 ERM 7 1 2 1 M650 Display 2 1 0 0 WDAM 6 0 0 0 ERSGEN30 4 1 0 0 M650 Firmware
125. s possible that a distracted poll worker could unknowingly and unintentionally install malicious firmware Prerequisites A deliberately altered PCMCIA card Impact A poll worker given an infected PCMCIA card going through typical election day procedures could unintentionally upload malicious firmware to the M100 Additionally if Unity were infected the malicious firmware could be distributed and created directly from Unity and installed by a poll worker on election day 7 3 4 The M100 locks are easily manipulated Description The M100 cabinet Scanner Ballot Box PCMCIA slot and power on off switch are locked with simple cam locks which can be easily picked in a short time using improvised tools Prerequisites An attacker would require privacy and a paper clip Impact Access to the PCMCIA slot would permit an attacker to perform any of the attacks mentioned here which make use of a PCMCIA card Additionally since these locks do not provide any evidence of tampering the fact that they are so easily bypassed makes discovery of this attack difficult 7 3 5 The keys for the M100 locks are the same across all M100 machines Description There are two keys for the M100 The ballot box key locks the M100 scanner in place and protects the PCMCIA slot ballot box and the cabinet doors The scanner key turns the power on and off to the M100 These two keys are differ from each other but are the same for all M100 machines These keys are ava
126. self and no data is read from the AutoMARK into Unity 39 5 3 Election Procedures This section describes how the ES amp S components discussed in this overview are used in an actual election We draw our information from the ES amp S documentation and assume that elections follow these general procedures though some counties may differ on specific procedures 5 3 1 Preparation Preparation for an election begins by setting up complete county and election databases using the EDM This is an involved and complicated process requiring an expert user The EDM stores all county precinct jurisdiction ballot styles contests registered voter totals and whatever other information is necessary for the election The set up of this database is so complicated that many counties rely on a service from ES amp S to create the database for them In addition to the election database ballots must be designed using either ESSIM for paper ballots or the iVIM for iVotronic electronic ballots Per election passwords for iVotronic DREs are also set at this point Once the election database has been created and ballot images prepared an election administrator uses the HPM to program all the media required by the different ES amp S voting hardware 5 3 2 Touchscreen DRE Voting The election process for DRE voting requires the HPM a Supervisor iVotronic terminal Compact Flash cards and PEBs Preparation At each new election an Election Qualification
127. sical security issues are discussed Finally a number of explicit attack scenarios are presented 9 1 Tools There are several basic tools that we have built to make the process of developing attacks on the ES amp S system more efficient and repeatable These are a framework for delivering the malicious payload to the iVotronic system a tool for reading and writing PEBs a serial debugger for the iVotronic a tool for reading and writing M100 PCMCIA memory cards a JTAG hardware debugger and a tool for extracting QNX files from the M100 These are discussed in the following sections Alec Yasinsac etal Software Review and Security Analysis of the ES amp S iVotronic 8 0 1 2 Voting Machine Firmware For the Florida Department of State February 23 2007 URL http election dos state fl us pdf FinalAudRepSAIT pdf Declan McCullagh E voting predicament Not so secret ballots CNET News com 2007 URL http www news com 2100 1014 _3 6203323 html 89 Copies of these tools have been delivered along with the private part of this report 9 1 1 A framework for delivering a malicious payload to iVotronic systems We have developed a collection of routines that infect the iVotronic firmware and take control over key voting machine functionality We refer to the collection as the payload because it is delivered by a Personalized Electronic Ballot PEB as part of an exploit More explicitly the payload is meant to be used b
128. so able compress a file using the same compression as the filesystem but there is no support for generating a filesystem from scratch We had access to the uncompressed versions of some of the files contained in the filesystem all the COTS components and text configuration files We validated the correctness of our dump utility by comparing the output files to the files we had access to The file we were most interested in getting off the filesystem was the main scanner application which we did not have a copy of We were able to extract this application and disassemble it 92 9 2 Physical Security and Security Seals It is our understanding that in some counties in Ohio the doors on the front of the iVotronic the Compact Flash slot in the iVotronic and the PCMCIA card slot in the M100 are guarded by tamper evident seals Unfortunately we were not given any samples of these seals therefore we could not determine how effective the seals are at preventing access to these components We also noted that none of the hardware devices contain factory installed tamper evident seals Neither the M100 nor the iVotronic contains factory installed tamper evident seals These devices are however shipped with a warranty void sticker on them but this is just a regular sticker that can easily be removed and replaced without a trace In addition the sticker is not very solid and often breaks just by handling the equipment Therefore a broken stick
129. splay for user input an RS232 serial port and two PCMCIA Type slots for loading ballot images and firmware updates and storing counted ballots The M100 performs a self test of its operating system on power up and checks for a properly formatted flash card in the PCMCIA slot The PCMCIA card is mapped directly into memory and portions of it are copied into RAM for faster access For the remainder of the data on the PCMCIA card the M100 builds an index in memory to data structures on the card The card is written to after each ballot is scanned recording either the votes cast for a valid ballot or the error for an invalid ballot There are two modes for the M100 selected using a key Open Close Polls and Vote When set to Open Close a number of administrative and diagnostic options are available which print summaries of the contents of the PCMCIA card Once done a poll worker selects the open polls or reopen polls menu option and turns the key to Vote when prompted In Vote mode the M100 operates in an automated fashion 38 only needing user interaction on invalid ballots At any point the M100 can be switched back to Open Close mode using the key 5 2 9 PCMCIA Memory Cards Unity via the HPM and the M100 use specially formatted PCMCIA SRAM flash storage cards for all communications The cards are formatted so that a small header can be loaded into the M100 s RAM which contains pointers into the SRAM for ballot definitions
130. sses password checks there is another iVotronic security feature required for access to some but not all administrative functions For these functions a PEB must be con figured with the correct Election Qualification Code EQC a 32 bit random number assigned for each election However as noted in the next section precinct poll workers and others with brief access to the poll worker equipment can easily extract this code from the precinct s supervisor PEB using a palmtop computer Note that even without the EQC however an attacker who needs no more access than that provided to a normal voter with a QA PEB or an emulated QA PEB can do a great deal of harm to an iVotronic terminal For example the EQC is not required on QA PEBs used to invoke the clear function on an iVotronic terminal a which erases all stored votes and renders the terminal useless for the rest of the election day Unauthorized PEB copying and alteration Anyone with physical access to polling station PEBs can easily extract or alter their memory This requires only a small magnet and a conventional IrDA based palmtop computer exactly the same kind of readily available hardware that can be used to emulate a PEB to an iVotronic terminal Because PEBs themselves enforce no passwords or access control features physical contact with a PEB or sufficient proximity to activate its magnetic switch and IR window is sufficient to allow reading or writing of its memory
131. tee secure code common software engineering practices are effective at improving the correctness and the resiliency of the system Good software engineering practices are critical to develop secure and reliable software and are particularly vital in the security sensitive context of elec tronic voting In contrast bad software engineering practices indicate haphazard design and implementation that is potentially rife with error Hence the software engineering practices employed by a system often speak to the overall quality of the code In this section we identify design and coding practices which deviate from our perception of good software engineering techniques 8 1 Complexity We were provided with nearly 670 000 lines of code written in 12 programming languages and compiled for five hardware platforms see Figure 8 1 Lines of code were counted using SLOCCount and the Linux we utility Given the size and breadth of the code base it is unlikely that any quality assurance QA process could conduct a comprehensive analysis of the entire system As a result the QA process will likely fail to find unintentional bugs and is even less likely to find malicious code surreptitiously inserted into the source code 8 1 1 Programming Languages Approximately 63 of the source code is written using programming languages that are memory unsafe These languages C C and assembly allow several classes of vulnerabilities including stack and heap
132. though such software is useful for rapid software development it is difficult to analyze the security properties of closed source third party systems Without access to the source code or a time consuming analysis of the third party software s binary objects these third party systems are used as black boxes under the possibly incorrect assumption that they are secure Since any vulnerability in a third party product is automatically inherited by the system using it such trust is unwarranted for security conscious applications 8 1 3 Insufficient Documentation Creating and configuring a ballot definition is an arduous process involving at least the following steps e Defining precincts districts and polling places T Jim etal Cyclone A safe dialect of C In USENIX Annual Technical Conference June 2002 George C Necula etal CCured type safe retrofitting of legacy software ACM Trans Program Lang Syst 27 2005 Nr 3 ISSN 0164 0925 84 e Assigning precincts and districts to polling places e Defining candidates contests ballot questions and referendums e Configuring election options e g candidate positions votes per contest etc e Generating ballot style information e Configuring the layout of paper ballots e Generating tabular files for the paper ballot layouts e Preparing election data for the M100 and M650 e Uploading election data to Compact Flash cards and PEBs for the iVotronic
133. ting must be done by physical examination of the VVPAT roll and permits electronic tabulation if the hand count shows no discrepancy It is unclear if electronic tabulation includes counting VVPAT ballots with a barcode reader See Ohio Secretary of State Directive 2007 30 Recount Procedures retrieved November 25 2007 from http www sos state oh us sos ElectionsVoter directives 2007 Dir2007 30 pdf 74 7 2 18 Accuracy testing mode detectable Description The logic and accuracy testing LAT of the iVotronic can be performed in two different ways either automatically or manually Automatic testing seems to be what is most common The automatic testing is performed by selecting a special logic and accuracy command in the administrator menu of the iVotronic The automatic test will then cast votes in a specific pattern without any user intervention In the manual mode the user manually casts votes and the result is tallied as a special logic and accuracy result The logic and accuracy test is effective at catching problems with the ballot programming but has very limited security benefits Any malicious firmware running on the iVotronic can detect that the logic and ac curacy test is running and function properly during this test During an automatic test no GUI functionality is ever tested All our example exploits hook into the GUI functions to perform the malicious activity so no action at all needs to be taken by the exp
134. ults from iV otronic This appears to be possible because firstly it is possible to report results for multiple precincts on a PEB and secondly analysis of the source code of Unity indicates that Unity does not check whether the returned PEB contains only results for precincts for which it was configured The attack via a PEB as opposed to one via a PCMCIA card was not experimentally verified Prerequisites To exploit this vulnerability an attacker must have either compromised the M100 optical scanner or have access to the PCMCIA card that is used to transfer the data to the Unity back end system For more details on prerequisites see Section 7 1 2 The attacker can also return an independently prepared PCMCIA card for results processing Impact An attacker such as a malicious poll worker can influence the results of an election by reporting fictitious results for different precincts The attacker will not only have complete control over the results being reported from the M100 from his or her precinct but can also report extra results for other precincts 7 1 4 Integrity of data on a PCMCIA card is not protected Description A PCMCIA card is used to transfer data from the M100 optical scanner to an iVotronic The integrity of the data on the card is protected only by CRC checks The protection is not cryptographically strong and CRC checks were not designed to protect against deliberate data modification This protection thus does not p
135. using separate and uncompromised hardware 7 4 2 M650 does not authenticate election definition and election macro language e code files Description The M650 accepts any well constructed election definition file or election macro language e code file located on an inserted Zip Disk No cryptographic authentication checks are used to ensure that the loaded definitions correspond to the paper ballots Malicious election definitions and e code can be trivially loaded by inserting a Zip Disk when the system is booted Prerequisites The attacker requires a Zip Disk containing a seemingly valid election definition that is one that conforms to the data structures defined in the M650 Functional Specification document The election definition and e code obtained from a legitimate Zip Disk can be used as a template to construct a malicious election definition Impact Using a malicious election definition Zip Disk an attacker can trivially swap candidate positions I See Section 22 7 4 1 in the confidential Annex Election Systems and Software Inc Software Specifications Model 650 Central Count Ballot Tabulator version 2 0 0 0 July 2004 79 B oe EVEREST software installed REPORTS Fon PREC PROCESSED F TOTALS BY PRECINCT p Laer oneone Figure 7 4 M650 with display controlled by forged firmware update disk ignore arbitrary positions on the ballot and or alter the weight the number of votes ass
136. validating that the code located in the upper 64KB of the firmware flash contains the original QNX kernel It is correct that the bootblock is write protected but the protection is not fool proof More specifically we accidentally overwrote two bytes of this part of the firmware during our evaluation The scanner stopped working at this point and we had to reprogram the bootblock using our earlier firmware dump 9 1 6 A tool for extracting the QNX filesystem from the M100 The main part of the M100 firmware consists of a filesystem that is mounted as the root filesystem by the kernel This filesystem contains a set of hardware drivers and startup scripts in addition to the main scanner application The filesystem is a proprietary QNX filesystem specifically made for flash memory Even though we had access to the latest QNX development environment we were not able to extract the files contained in this filesystem The filesystem contained in the firmware image was created with an old version of the QNX development tools which is no longer supported by QNX Since we could not find any tools to access the filesystem or any description of the format of the filesystem we had to reverse engineer the format The content of the filesystem is compressed in order to save memory which further complicated the reverse engineering We created a tool that given a firmware image will extract and decompress all the files contained in the filesystem The tool is al
137. y are ever manually scrutinized since the portions printed using the reflective ink are absent better forgeries can be constructed by ob taining IR reflective non read ink Such ink is available for general purchase at online vendors or can be easily made from commodity ink jet printer supplies The M100 accepts a commodity paper in a variety of weights Prerequisites Access to the M100 ballot box see 7 3 4 and 7 3 5 Impact A motivated forger can produce paper ballots that visually appear legitimate and that are accepted by the M100 78 7 4 M650 7 4 1 M650 runs executable on Zip Disk on power up Description On boot the M650 checks for the presence of a firmware update disk Firmware update disks are commodity Zip disks provided by ES amp S that contain updated programs binary executables and an installer script The M650 determines whether a Zip Disk is a firmware update disk by checking for the existence of three files If these files exist and the reported version number does not match the currently installed firmware version the installer script located on the Zip Disk is executed Only the contents of the file containing the update version number are examined That is the M650 checks only for the existence of the three files and performs no integrity or authenticity checks Hence any person with physical access to the machine can load new software onto the M650 either on before or after the election As is also the case
138. y exploits in order to infect a voting machine when a PEB is inserted in the iVotronic The payload is made up of four different parts shellcode flasher linker and hooks These are discussed in the following sections Shellcode The shellcode is a small 32 bytes piece of code that is shipped with the exploit The main purpose of the shellcode is to execute code stored on the PEB This is achieved by loading one block of the PEB into RAM and then jumping to it Flasher The flasher code which is part of the malicious code on the PEB is loaded into RAM by the shellcode The task of the flasher is to first load the rest of the payload including the linker into RAM and then to copy this code to an unused area of the iVotronic s firmware flash memory The code is copied to the flash memory so that it will be persistent The final task of the flasher is to execute the linker Linker The linker s task is to modify the original iVotronic firmware so that key function calls are in tercepted and diverted to the hooks More specifically the linker overwrites the target addresses of the function calls that are to be intercepted and replaces each with an address that points to the payload s hooks The linker also updates the firmware s Cyclic Redundancy Check CRC so that it will pass the iVotronic validation tests Hooks The hooks are a set of functions that are linked into the original firmware Most hooks perform malicious activity

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