1. Taking Total Control of Voting Systems: Firmware Manipulations on an Optical Scan Voting Terminal Nicolas Nicolaou Voting Technology Research (VoTeR) Center Department of Computer Science and Engineering University of Connecticut http://voter.engr.uconn.edu 24th Annual ACM Symposium on Applied Computing SAC 2009, Honolulu, Hawaii Joint work with: Seda Davtyan, Sotiris Kentros, Aggelos Kiayias, Laurent Michel, Alexander Russell, Narasimha Shashidhar, Andrew See and Alexander A. Shvartsman

2. Motivation  Electronic Voting Technologies  Direct Recording Electronic (DRE)  Touch Screen w/ or w/out printer, not directly voter-verifiable  Optical Scan (OS) tabulator  VVPAT – Voter Verifiable Paper Audit Trail  Used in over 50% of counties in 2008  Case Study, Premier AccuVote-OS (AVOS):  Wide use in US elections, but…  C an be tampered with if memory card is removed [Hursti’05]  Can be tampered with if memory card is sealed in [EVT’07]  Reports by other workers and CA, CT, FL, AL,…  Safe-use procedures can be followed, but all under the assumption that firmware is trusted 10/8/20152VoTeR Center – SAC’09

3. Question Can the Firmware of Voting Machines be Trusted? In particular: Can the Firmware of AccuVote tabulator be Trusted? 10/8/20153VoTeR Center – SAC’09 Work performed by the UConn VoTeR Center on request of the Connecticut Secretary of the State as a part of the overall effort to evaluate voting equipment, and to enable and perform effective technological audits, pre- and post-election.

4. Our Findings  Firmware of AVOS can be analyzed  Without access to vendor specifications or source code  Using off-the-shelf third party tools (<$300)  Under the contractual right to “display or disseminate all information and data related to election results”  Three firmware manipulations targeting:  Enabling Effective Auditing:  Faithful and fast memory dumping  Audit Improvement (also potential Privacy Violation):  “Leak” Ballot Contents  Revealing Weaknesses: Alteration of Election Result  Swapping candidate counters 10/8/20154VoTeR Center – SAC’09

5. Understanding the System  Election Management System (GEMS):  Ballot Design and Central Tabulation  Serial port communication with AVOS  Transferred data stored on the AVOS memory card  AVOS Terminal:  Hardware Components  Software Components  Firmware  Memory Card Contents 10/8/20155VoTeR Center – SAC’09

6. Hardware  External  LCD  Dot Matrix Printer  Ballot Reader  Input Buttons  128K 40 Pin Epson Memory Card  Internal  8Mhz MicroController  Emulates an Intel 80186  128K SRAM  128K Firmware EPROM 10/8/20156VoTeR Center – SAC’09

7. Software  Firmware  Version 1.96.6  Stored in a UV light erasable 128K EPROM  Responsible for all the functions of the terminal  Unencrypted / Unauthenticated: the terminal will boot modified firmware without a single warning  Memory Card contents  Programmed through GEMS  Election-specific programming  Election Data and Control Flags depending on the Elections 10/8/20157VoTeR Center – SAC’09

8. Understanding Memory Card Format  Crucial for Auditing purposes  Memory Card can be divided in 5 major sections:  Header  Log  Election Data  Bytecode (AccuBasic)  Counters 10/8/20158VoTeR Center – SAC’09

9. Gaining Access: Serial Port  Control over the transmission  One way communication from terminal via a serial line  Identified AVOS communication Methodology  Place byte to be sent in a buffer  Unmask the serial transmission interrupt to place the byte from the byte on the wire. 10/8/20159VoTeR Center – SAC’09

10. Manipulation 1: AVOS as a Card Reader  Goal: Transmit MC data from AVOS to PC  Improve Auditing  Obtain clean and faithful image of the card contents  Enable auditing of large number of cards  Motivation  AVOS built-in dumping procedure  Unfaithful transmission of the contents  Potential modification of the audit log  Too slow for mass auditing ( ~2min per card)  Card Reader/Writer are very hard to find and are slow  This type of memory cards discontinued ca. 1998  Even if available, the commercial reader can take 1/2 hour 10/8/201510VoTeR Center – SAC’09

11. Manipulation 1: AVOS as a Card Reader  Delivery of Memory Card Data:  Inject a function to read the memory card contents  Utilizing Memory Card access control  Transmit one byte at a time to the serial line  Utilizing Serial Port access control  Speeding Up Card Dumping:  Implemented standard Run Lengths Encoding algorithm  Large part of card data contains sequences of identical values  Reduced card dumping from 2min to 20sec  Enabled the dump and inspection of large number of cards  Avoid alteration of card contents, e.g., audit log 10/8/201511VoTeR Center – SAC’09

12. Manipulation 2: Leaking Ballot Data  Dual Significance of the Result:  Benign alteration of firmware: Enhance Hand Count Audit  Potential malicious alteration: Violation of Voter Privacy  Implementation  AVOS side:  Transmit the candidate counters after each ballot cast  PC side:  Wait for incoming counters  Upon receipt of counters compute the difference of current counter image and the locally stored counter image  Counter difference reveal the ballot votes 10/8/201512VoTeR Center – SAC’09

13. Manipulation 2: Leaking Ballot Data  Used in Hand Count Audit  Ballot as read by AVOS presented on the screen  Poll worker may verify validity of the ballot  Reduces audit time  Reduces audit errors  Reveals ballot read errors  Demonstrates Possible Violation of Voter Privacy  Using the same technique during the election  Extract order of the ballots cast  Next: Hybrid OS terminal that displays votes as cast  Voter could verify their votes as recorded by the machine 10/8/201513VoTeR Center – SAC’09

14. Manipulation 3: Swapping Candidate Counters  Time Bomb Attack during Election  Behave “nicely” during pre-election testing  “Hit” during the actual elections  Implementing vote swapping:  Swap votes for predefined candidates  If votes < threshold do not swap  Also avoids pre-election testing detection  Otherwise swap after the elections are closed  Swap is done at the closing of elections and before the election report is printed. 10/8/201514VoTeR Center – SAC’09

15.  Demonstration T=10: Pre-Election Testing Manipulation 3: Swapping Candidate Counters Original Firmware Modified Firmware 10/8/201515VoTeR Center – SAC’09

16.  Demonstration T=10: At Poll Closing Manipulation 3: Swapping Candidate Counters Original Firmware Modified Firmware 10/8/201516VoTeR Center – SAC’09

17. Conclusions and Discussion  Demonstrated 3 AVOS firmware manipulations  Used for: Fast and Faithful Memory Card dumping  Potential for: Leaking Ballot Data  Potential for: Swapping Candidate Counters  Our results underscore the need for  Pre and Post election audits  Incorporation of firmware cryptographic integrity check at the hardware level  Answer to our question:  Firmware of an e-voting terminal is not necessarily trustworthy 10/8/201517VoTeR Center – SAC’09

18. Thank you! Questions? 10/8/201518VoTeR Center – SAC’09