July 18, 2019

ImageCast Evolution voting machine: Mitigations, misleadings, and misunderstandings

Two months ago I wrote that the New York State Board of Elections was going to request a reexamination of the Dominion ImageCast Evolution voting machine, in light of a design flaw that I had previously described. The Dominion ICE is an optical-scan voting machine. Most voters are expected to feed in a hand-marked optical scan ballot; but the ICE also has an integrated ballot-marking device for use by those voters who wish to mark their ballot by machine. The problem is, if the ICE’s software were hacked, the hacked software could make the machine print additional (fraudulent votes) onto hand-marked paper ballots. This would defeat the purpose of voter-verifiable paper ballots, which are meant to serve as a safeguard against buggy or fraudulent software.

The Board of Elections commissioned an additional report from SLI Compliance, which had done the first certification of this machine back in April 2018. SLI’s new report dated March 14, 2019 is quite naive: they ran tests on the machine and “at no point was the machine observed making unauthorized additions to the ballots.” Well indeed, if you test a machine that hasn’t (yet) been hacked, it won’t misbehave. (SLI’s report is pages 7-9 of the combined document.)

The Board of Elections then commissioned NYSTEC, a technology consulting company, to analyze SLI’s report. NYSTEC seems less naive: they summarized the issue under examination as follows:

NYSTEC, NYS State Board of Elections and computer science experts have long agreed that when an adversary has the ability to modify or replace the software/firmware that controls a voting machine then significant and damaging impacts to an election are possible. What makes this type of attack [the one described by Prof. Appel] different however is that the voted paper ballots from a compromised combination BMD/scanner machine could not be easily used to audit the scanner results because they have been compromised. If the software/firmware was compromised to alter election results, on a regular scanner (without BMD capabilities) one still has the voted ballots to ensure the election can be properly decided. This would not be the case with the
BMD/scanner attack and if such an attack were to occur, then a forensic analysis would be needed on all ballots in question to determine if a human or machine made the mark. Such a process is unlikely to be trusted by the public.

[page 12 of the combined document]

NYSTEC’s report (and not just this paragraph) agrees that (1) the hardware is physically capable of marking additional votes onto a voted ballot and (2) this is a very serious problem. SLI seems more confused: they say the source code they reviewed will not (ask the hardware to) mark additional votes onto a voted ballot.

Mitigations (practical or not?)

NYSTEC suggests that the problem could be mitigated by physically preventing the hardware from printing votes onto any ballot except when the machine is deliberately being used in BMD mode (e.g., to accommodate a voter with a disability). Their suggested physical mitigations are:

* Leave the printer access panel open as this will prevent an unauthorized ballot from being marked without detection.

* Remove the printer ink and only insert it when the system is being used in BMD mode.

* Insert a foam block inside the printer carriage, as this will prevent the system from ever printing on an already voted ballot.

[page 73 of the combined document]

Then they explain why some of these physical mitigations “may not be feasible.”

Without the mitigations, NYSTEC rates the “Impact” of this Threat Scenario as “Very High”, and with the mitigations they rate the impact as “Low”.

Misleadings

Based on the reports from SLI and NYSTEC, the operations staff (Thomas Connolly, Director of Operations) of the Board of Elections prepared a 3-page recommendation [pages 2-4 of the combined document]. The staff’s key statement is a mischaracterization of NYSTEC’s conclusion: they write, “NYSTEC believes that SLI security testing of the Dominion source code provided reasonable assurance that malicious code that could be triggered to enable the machine to print additional marks on an already marked ballot, is not present in the version tested.”

Yes, NYSTEC remarks in passing that Dominion’s source code submitted for review does not already contain malicious code, but that’s not the conclusion of NYSTEC’s own report! NYSTEC’s actual recommendation is that this is a real threat, and election officials who use this machine should perform mitigations.

The staff’s recommendation is to mitigate by (1) leaving the printer access panel open, which prevents printed-on ballots from proceeding automatically to the ballot box (a “preventative control”), (2) checking the printer’s “hardware counter” at the close of polls to see if more pages were printed on than the number of voters who used BMD-mode (a “detective control”), and (3) instructing pollworkers to be aware of the “printer running when it should not be” (a “detective control”). (I wonder whether the so-called “hardware counter” is really under the control of software.)

The NY State Board of Elections, at its meeting of April 29, 2019, accepted the recommendations of the Board staff. (This video, from 37:30 to 44:20). Commissioner Kellner did point out that, indeed, it is a misunderstanding of computer security to say that because the malicious code is not already present in the source code, there is no threat from malicious code.

Misunderstandings (deliberate or not?)

The Board of Elections also directed Dominion to revise its “Threat Register”, that is, the security threats that should be considered when assessing the robustness of their voting machines. In response to the SLI and NYSTEC reports, Dominion added this:

Tampering with installed software
Description – The software installed on the PCOS devices is reviewed, built and tested by a Voting System Test Lab (VSTL). These Trusted Builds are installed on the PCOS devices and control their operation. A special set of credentials is required to install the software and integrity checks are performed during installation to ensure a valid build is being installed. Hash values are generated by the VSTL for both the installation files and the files on the PCOS device after installation. The hash values are recorded in a System ID Guide for jurisdictions to use to verify the integrity of the PCOS software.
Threat – A malicious actor obtains unauthorized physical access to the PCOS devices after pre-election “logic and accuracy” testing but before Election Day, successfully defeating the physical controls that Election Administrators have in place. The installation software is counterfeited and fraudulent software is installed. The malicious actor also defeats the controls in place related to the hash codes which are verified on Election Day. Then, this malicious actor once again obtains unauthorized physical access to the PCOS devices after the Election, again defeating physical security practices in place, and installs the certified software after Election Day.
Impact – By changing the software, the malicious actor makes the voting system inaccurate or inoperable.
Impacted security pillars – Integrity and availability.
Risk rating – Low.
Mitigation – Implement proper processes (access control) for memory card handling and device storage. Verify the integrity of the installation software prior to and after installation. During points where the physical chain of custody of a device is unknown, verify the integrity of the installed software. Cryptographic and digital signing controls mitigate tampering with installation software. Tampering is evident to operators when verifying the software installed on the device. For more information, refer to Sections 4 and 5.5 of this document. Also, refer to the VSTL generated hash values.

[Page 76 of the combined document]

There are two things to note here. First, this wasn’t already in their Threat Register by 2018? Really? Computer Scientists have been explaining for 20 years that the main threat to a voting machine is that someone might install fraudulent vote-stealing software, and Dominion Voting Systems didn’t notice that?

Second, Dominion has written the Threat description in a very limited way: someone has physical access to the machine. But the threat is much broader than that. For example:

(1) Someone anywhere in the world hacks into the computer systems of Dominion Voting Systems and alters the firmware-update image to be installed on new or field-upgraded voting machines. [Notice how they use the passive voice, “These Trusted Builds are installed on the PCOS devices” to avoid thinking about who installs them, and how they are installed, and what threats there might be to that process!]   Now it doesn’t correspond to the source code that was inspected and certified. The hacker doesn’t need physical access to the voting machines at all! And the “hash codes” are not much help, because the fraudulent software can report the nonfraudulent hash codes.

Or, (2) Someone steals the cryptographic keys, thus defeating the “cryptographic and digital signing controls.”

Or (3) Don’t do it just before the election, do it once and let it be in effect for 10 elections in a row.

Or (4) Bypass all the “cryptographic and digital signing controls” by hacking into the lower levels of the computer, through the BIOS, or through the OS, or the USB drivers, etc.

Or (5), (6), (7) that I don’t have room to describe or haven’t even thought of. The point is, there are many ways into a computer system, and Dominion paints a false, rosy picture when limiting it to the same physical access attack that was already demonstrated on their previous generation of machines.

Conclusion

No one is asking companies like Dominion to do the impossible, that is, build a perfectly secure voting machine. (Well, actually, some people are asking, but please let’s recognize that it’s impossible.) Instead, we just want two things:

  1. Make them as secure as you can. Those “cryptographic and digital signing controls” are better than nothing (and weren’t present on voting machines built 15 years ago).
  2. Recognize that there’s no way to absolutely prevent them from being hacked, and that’s why we need Risk-Limiting Audits of the paper ballots. But those RLA’s won’t be effective if the hardware of the machine is designed so that (under the control of hacked software) it can mark more votes on the ballot after the last time the voter saw the paper.

And I ask New York State: If some county actually buys these machines, will the county be required to adopt the mitigation procedures approved at the April 29th Board meeting?

Comments

  1. Kevin Skoglund says:

    The recommended procedural controls are ridiculous. The report even points out their flaws.

    It is naive to assign a critical security task to hundreds of loosely-organized, part-time poll workers spread across a city. Many poll workers are older and not tech-savvy. They are working 14-hour days and occupied with many other distracting tasks–like running the election. Yet they are expected to remember to perform an awkward procedural control reliably from election to election.

    The conclusion that there is “zero risk” if the mitigations are in place fails to consider the high likelihood that mitigations will not be in place. Some poll workers may get it right once, but by the next election the security-critical foam block may get lost or poll workers forget why it is in their election supplies. This design flaw continues to be a very high risk. It is insecure by default and only secure if handled with an unrealistic level of precision.

    And what about the risk to assisted voting sessions? The implication of this decision is that it is acceptable for ballots by voters with disabilities to be vulnerable to manipulation as long as the other ballots are protected.

    This was a disappointing decision by the NYS BOE. They got bad security advice, and they did not notice because they barely considered it.

  2. Lulu Friesdat says:

    2 NY counties have already purchased these machines, and a third is leasing them. The Dominion ICE and the ExpressVote XL, which has the same security flaw are in use in 6 swing states including WI, FL, OH & PA. Please watch our investigation featuring Professor Appel.
    https://smartelections.us