Daily Archives: 04/03/2014

TLS design weakness affecting client side authentications

A team of security research discover a weakness in TLS design, quote form their website

“A is malicious, it can choose a non-prime group such that the resulting PMS is fully under its control.
if a malicious server Amounts a UKS attack to obtain two sessions (one with C and the other with S) that share the same MS, ciphersuite, and SID, it can forward the abbreviated handshake unchanged from one connection to the other
The easiest mitigation is for web browsers to refuse a change of server identity during renegotiation
Major browsers fixed this. However, there are numerous non-browser TLS clients. It will take lots effort to patch them. This type of weakness is difficult to identify and fix, as the impact is not obvious or cannot be seen by the user.
With almost 20 years passed since TCP/IP invented, most of the low hanging security issues are identified and addressed. We are going to see more occurrence of this type of fundamental and subtle design weaknesses.
The battlefield for security professional is just added another 100 miles !