A Retrospective on the Use of Export Cryptography

Presented at Black Hat USA 2016, Aug. 3, 2016, 10:20 a.m. (50 minutes).

TLS has experienced three major vulnerabilities stemming from "export-grade" cryptography in the last year---FREAK, Logajm, and Drown. Although regulations limiting the strength of cryptography that could be exported from the United States were lifted in 1999, and export ciphers were subsequently deprecated in TLS 1.1, Internet-wide scanning showed that support for various forms of export cryptography remained widespread, and that attacks exploiting export-grade cryptography to attack non-export connections affected up to 37% of browser-trusted HTTPS servers in 2015. In this talk, I'll examine the technical details and historical background for all three export-related vulnerabilities, and provide recent vulnerability measurement data gathered from over a year Internet-wide scans, finding that 2% of browser-trusted IPv4 servers remain vulnerable to FREAK, 1% to Logjam, and 16% to Drown. I'll examine why these vulnerabilities happened, how the inclusion of weakened cryptography in a protocol impacts security, and how to better design and implement cryptographic protocols in the future. Having been involved in the discovery of all three export vulnerabilities, I'll distill some lessons learned from measuring and analyzing export cryptography into recommendations for technologists and policymakers alike, and provide a historical context for the current "going dark'' and Apple vs. FBI debate.


Presenters:

  • David Adrian - University of Michigan
    David Adrian is a former intern at Duo Security, who got lost on the way to work one day and ended up a graduate student at the University of Michigan, where he does computer security research. David was involved in the discovery and disclosure of FREAK, Logjam, and Drown. He also helps maintain ZMap, and is one of the creators Censys.io. He apologizes if any of his Internet-wide scanning shenanigans caused an alert in your IDS.

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