This paper investigates the security of Diffie-Hellman key exchange as used in popular Internet protocols and find it to be less secure than widely believed. First, they present Logjam, a novel flaw in TLS that lets a man-in-the-middle downgrade connections to "export-grade" Diffie-Hellman. To carry out this attack, the researchers implement the number field sieve discrete log algorithm. After a week-long precomputation for a specified 512-bit group, they can compute arbitrary discrete logs in that group in about a minute. They found that 82% of vulnerable servers use a single 512-bit group, allowing them to compromise connections to 7% of Alexa Top Million HTTPS sites. They go on to consider Diffie-Hellman with 768- and 1024-bit groups. They estimate that even in the 1024-bit case, the computations are plausible given nation-state resources. A small number of fixed or standardized groups are used by millions of servers; performing precomputation for a single 1024-bit group would allow passive eavesdropping on 18% of popular HTTPS sites, and a second group would allow decryption of traffic to 66% of IPsec VPNs and 26% of SSH servers. A close reading of published NSA leaks shows that the agency's attacks on VPNs are consistent with having achieved such a break. They conclude that moving to stronger key exchange methods should be a priority for the Internet community.
34229b5a84df1c71f6a8f6c2fbd22fb444d37a13ea7fdfe2f50f3fe60983e984The safety critical nature of traffic infrastructure requires that it be secure against computer-based attacks, but this is not always the case. The authors investigate a networked traffic signal system currently deployed in the United States and discover a number of security flaws that exist due to systemic failures by the designers. They leverage these flaws to create attacks which gain control of the system, and we successfully demonstrate them on the deployment in coordination with authorities. Their attacks show that an adversary can control traffic infrastructure to cause disruption, degrade safety, or gain an unfair advantage. They make recommendations on how to improve existing systems and discuss the lessons learned for embedded systems security in general.
7eb72c4fe42431b49f23e36bae8a9024cdacfdd85d7d3cab51bf021cdf47aca7Whitepaper called Attacking the Washington, D.C. Internet Voting System. In 2010, Washington, D.C. developed an Internet voting pilot project that was intended to allow overseas absentee voters to cast their ballots using a website. The authors of this paper participated in a challenge to break the security of the system and in doing so, elected Bender from Futurama to the school board.
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