Assessing and Exploiting BigNum Vulnerabilities

Presented at Black Hat USA 2015, Aug. 6, 2015, 2:30 p.m. (50 minutes)

The majority of deployed asymmetric cryptography implementations (RSA, DH, ECDH/ECDSA with GF(p) curves) need to perform calculations on integers that are larger than a single machine word. Just like every software package, implementations of multi-precision integer arithmetic sometimes have bugs. This talk investigates the implications of these bugs and shows how they can be used by attackers to exploit asymmetric cryptographic primitives. Isolating bug patterns and understanding exploitation requirements allows us to develop strategies for automated bug hunting.

Presenters:

• Ralf-Philipp Weinmann - Comsecuris
  Ralf-Philipp Weinmann is the founder of Comsecuris, a boutique research and consulting company offering services in the information security domain. Previously he was a postdoctoral researcher at the University of Luxembourg. He received both his Diplom and his PhD from the Technical University of Darmstadt in Germany, both on topics in crypology. He is driven by the desire of finding new and innovative ways to subvert security assumptions.

Links:

• https://www.blackhat.com/us-15/briefings.html#assessing-and-exploiting-bignum-vulnerabilities
• https://infocon.org/cons/Black Hat/Black Hat USA/Black Hat USA 2015/video/Black Hat USA 2015 - Assessing And Exploiting BigNum Vulnerabilities.srt (subtitles)
• https://infocon.org/cons/Black Hat/Black Hat USA/Black Hat USA 2015/video/Black Hat USA 2015 - Assessing And Exploiting BigNum Vulnerabilities.mp4
• https://www.youtube.com/watch?v=oje2ZgUzARo