There's a new TLS protocol security vulnerability found that can be exploited using protocol downgrade that was left in place due to previous U.S. government export restrictions its been named "Logjam". It affects servers supporting the Diffie-Hellman key exchange, and it's caused by export restrictions mandated by the U.S. government during the Clinton administration. "Attackers with the ability to monitor the connection between an end user and a Diffie-Hellman-enabled server that supports the export cipher can inject a special payload into the traffic that downgrades encrypted connections to use extremely weak 512-bit key material. Using precomputed data prepared ahead of time, the attackers can then deduce the encryption key negotiated between the two parties."
Internet Explorer is the only browser yet updated to block such an attack — patches for Chrome, Firefox, and Safari are expected soon. The researchers add, "Breaking the single, most common 1024-bit prime used by web servers would allow passive eavesdropping on connections to 18% of the Top 1 Million HTTPS domains. A second prime would allow passive decryption of connections to 66% of VPN servers 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." Here is their full technical report (PDF).
Time for a complete overhaul?
[Update: Thanks to Canopic Jug for locating and providing a link to the Common Vulnerabilities and Exposures entry CVE-2015-4000; check there for official information and updates.]
(Score: 4, Interesting) by frojack on Thursday May 21 2015, @06:40AM
I've read somewhere that this is the exploit used to pierce most VPNs, both hardware and software implementations, and allowed the NSA to read VPN traffic pretty much at will.
No, you are mistaken. I've always had this sig.
(Score: 2) by mtrycz on Thursday May 21 2015, @09:59AM
Care to share the source. I don't fancy anecdotal facts much.
In capitalist America, ads view YOU!
(Score: 3, Informative) by kadal on Thursday May 21 2015, @11:18AM
It's in the PDF article, near the end
(Score: 2) by mtrycz on Thursday May 21 2015, @11:47AM
Great, thanks.
In capitalist America, ads view YOU!