Black Box Voting : Latest Consumer Reports from Black Box Voting: 5-11-06: Three-level security flaws found in Diebold touch-screens ------------------------------------------------------------
Posted by Bev Harris on Thursday, May 11, 2006 - 12:34 pm:
Due to the nature of this report it is distributed in two different versions. Details of the attack are only in the restricted distribution version considered to be confidential. Fewer than 50 words have been redacted in the version below.
Note: Please refrain from speculation or public discussion of inappropriate technical details.
This document describes several security issues with the Diebold electronic voting terminals TSx and TS6. These touch-pad terminals are widely used in US and Canadian elections and are among the most widely used touch pad voting systems in North America. Several vulnerabilities are described in this report.
One of them, however, seems to enable a malicious person to compromise the equipment even years before actually using the exploit, possibly leaving the voting terminal incurably compromised.
These architectural defects are not in the election-processing system itself. However, they compromise the underlying platform and therefore cast a serious question over the integrity of the vote. These exploits can be used to affect the trustworthiness of the system or to selectively disenfranchise groups of voters through denial of service.
Three-layer architecture, 3 security problems
Each can stand alone or combine for 3-layer offense in depth
As an oversimplification, the systems in question have three major software layers: boot loader, operating system and application program. As appropriate for current designs, the first two layers should contain all hardware specific implementations and modifications, while the application layer should access the hardware – the touch pad, memory card, the network etc. – only via services and functions provided by the operating system and therefore be independent of the hardware design. Whether the architecture in question follows these basic guidelines is unknown.
Based on publicly available documentation, source code excerpts and testing performed with the system, there seem to be several backdoors to the system which are unacceptable from a security point of view. These backdoors exist in each of these three layers and they allow the system to be modified in extremely flexible ways without even basic levels of security involved.
In the worst case scenario, the architectural weaknesses incorporated in these voting terminals allow a sophisticated attacker to develop an "offense in depth" approach in which each compromised layer will also become the guardian against clean-up efforts in the other layers. This kind of deep attack is extremely persistent and it is noteworthy that the layers can conceal the contamination very effectively should the attacker wish that. A quite natural strategy in these types of situations is to penetrate, modify and make everything look normal.
Well documented viral attacks exist in similar systems deploying interception and falsification of hash-code calculations used to verify integrity in the higher application levels to avoid detection. The three-level attack is the worst possible attack. However, each layer can also be used to deploy a stand-alone attack. The TSx systems examined appear to offer opportunities for the three-level attack as well as the stand-alone attacks.
It is important to understand that these attacks are permanent in nature, surviving through the election cycles. Therefore, the contamination can happen at any point of the device's life cycle and remain active and undetected from the point of contamination on through multiple election cycles and even software upgrade cycles.