According to Mozilla, Microsoft and Google, TURKTRUST issued a pair of incorrect subsidiary certificate authorities. The subsidiary CAs then issued illegitimate SSL certificates for *.google.com
"Late on December 24, Chrome detected and blocked an unauthorized digital certificate for the "*.google.com" domain," Adam Langley, software engineer at Google, wrote in a blog post. "Intermediate CA certificates carry the full authority of the CA, so anyone who has one can use it to create a certificate for any website they wish to impersonate."
Google updated its SSL certificate revocation list on Dec. 26, blocking the two fraudulent certificates. Microsoft issued an advisory on Jan. 3, disclosing that it was aware of active attacks using a fraudulent digital certificate issued by TURKTRUST. Microsoft also automatically blocked the two fraudulent certificates for Windows users with an update.
Mozilla is also revoking trust for the TURKTRUST certificates, though not quite as fast.
"Mozilla is actively revoking trust for the two mis-issued certificates which will be released to all supported versions of Firefox in the next update on Tuesday 8th January," stated Michael Coates, director of Security Assurance at Mozilla.
Though Microsoft stated it was aware of attacks using the TURKTRUST certificates, TURKTRUST itself has not made a similar admission. "There is also no evidence of any attack on hacking on our systems and of any malicious usage," TURKTRUST said in a statement.
TURKTRUST noted that its systems were upgraded in the May to November of 2011 timeframe in order to be compliant with the ETSI TS 102 042 CA System Management Standard. During that upgrade cycle, TURKTRUST claims the fraudulent certificates were issued, due to a "…defective data migration and software upgrade process."
Not a New Issue
The issue of defective CA certificates is not a new one. In 2011, Dutch certificate authority DigiNotar similarly issued fraudulent certificates for *.google.com.
In the DigiNotar case, however, the root cause was identified as breach of the DigiNotar infrastructure. Instead of just blocking individual certificates issued by DigiNotar, browser vendors ended up blocking DigiNotar entirely.
The DigiNotar incident followed an exploitation of CA Comodo earlier in 2011. In the Comodo incident, the company blamed attackers from Iran for the exploit.
Andrew Storms, director of security operation for nCircle, told eSecurity Planet that even though the TURKTRUST incident appears to have been the result of faulty internal business processes, users still need to worry.
"For Internet users, it doesn’t matter how the breach happened because the end result is the same," Storms said. "Users are fooled and their private information is stolen."
Storms also expects TURKTRUST will not be the last CA to experience a security incident. A CA is a high-value target for attackers, and he expects the market will continue to see successful attacks at least occasionally.
"These attacks remind people that the centralized authority structure we use has its drawbacks, but the certificate authority is so deeply ingrained in the infrastructure of the Internet it will require an enormous effort to change," Storms said.