Security → Re: Flame: Massive cyber-attack discovered, researchers say

SSL security flaw with MD5 certificates announces today
The problem is that many sites like banks, brokerages, credit card companies, and major online web sellers are all using MD5 certificates. I checked and my credit card company, my bank, & Google Gmail are all still using MD5 certificates.

»news.cnet.com/8301-1009_3-101296···1_3-0-20
A key piece of Internet technology that banks, e-commerce sites, and financial institutions rely on to keep transactions safe suffers from a serious security vulnerability, an international team of researchers plans to announce Tuesday.

They plan to demonstrate how to forge security certificates used by secure Web sites, a process that would allow a sufficiently sophisticated criminal to fool the built-in verification methods used by all modern Web browsers--without the user being alerted that anything was amiss.

Their work has focused on finding vulnerabilities in a technology known as Secure Sockets Layer, or SSL, which was designed to provide Internet users with two guarantees: first, that the Web site they're connecting to isn't being spoofed, and second, that the connection is encrypted and is proof against eavesdropping. SSL is used whenever a user navigates to an address beginning with "https://".

The attack exploits a mathematical vulnerability in the MD5 algorithm, one of the standard cryptographic functions used to check that SSL certificates (and thus the corresponding Web sites) are valid. This function has been publicly known to be weak since 2004, but until now no one had figured out how to turn this theoretical weakness into a practical attack.

When MIT professor Ron Rivest developed MD5 in 1991, it was considered sufficiently secure. But starting in 1996, a series of increasingly serious flaws started calling the continued viability of MD5 into question.

"The main message here is to stop issuing MD5 certificates, now," said Molnar. He believes that MD5 is so weak it no longer should be used for any applications: "More secure, freely available alternatives exist." (In November 2005, the U.S. government announced plans to find successors to MD5 and SHA-1, an official federal standard with its own problems. The new federal standard will be called SHA-3.)

Appelbaum estimates that 30 percent to 35 percent of all SSL certificates currently in use have an MD5 signature somewhere in their authentication chain. "The CAs should contact every customer that currently uses an MD5-signed certificate and offer a free replacement."