This weekend Google security engineer, Adam Langley, (we will get to the irony of the last name in a bit) blogged about an agency within the French Government and its misuse of its intermediate CA. The French cyber-defense agency, ANSSI, had improperly issued "duplicates" of certificates for some Google domains. It appears they went as far to ensure that the certificates carried enough information to display to any user that the certificate was the legitimate site certificate even though it was issued improperly. Google has started to work with the browser manufacturers to effectively block this intermediate so look for browser updates over the next few days. ARSTechnica article is here.
This does raise some interesting thoughts. First off is the fact that Langley (has anyone else made the link to the other "famed" Langley location and the fact that ANSSI is the "cyber defense" agency in France?) was looking at these types of organizations given the recent announcements from Google, Yahoo, Twitter etc as to the push to rein in the NSA programs for monitoring. It appears that Google, and likely others, will be doing some checks that the operators of the Global Roots should be doing all along and sampling the certificates issued by the intermediate CAs. This sampling usually only takes place after the car has gone off the cliff. I had to go through every issued certificate for our CAs after Diginotar - "just to make sure". But a sampling on an irregular basis would do wonders for issuance confidence.
So if we are to assume that the Root operators are not doing their jobs to protect the issuance process what do we do? Well options have and are further developing. One of the most promising is certificate pinning - which provides a way to link a site to a specific certificate and even if another certificate from a valid CA appears to be valid it will be ignored. It does seem to me that we should not have to do these things but since we cannot rely on Root operators to protect their brand then we need to do things to protect ourselves.
For those CA operators out there - make sure you either have good control over issuance OR put in place mechanisms to randomly audit issued credentials so you can provide a way to protect your brand.
