The hack attack that minted a fraudulent authentication credential for Google.com may have affected hundreds of other websites, a review of source code for Google's Chromium browser suggests.
A side-by-side review comparing code contained in an upcoming version of Chrome increased the number of secure sockets layer certificates hardcoded in the browser's blacklist by 247. A comment accompanying the additions said: “Bad DigiNotar leaf certificates for non-Google sites.”
As previously reported, Microsoft, Google, Firefox, and other software makers announced updates on Monday to prevent their products from trusting SSL certificates issued by DigiNotar. They took the unprecedented move following Monday's discovery that the Netherlands-based certificate authority had issued a bogus certificate for Gmail, Google Docs, and other Google services that was being used to target people in Iran.
In a press release that raised new concerns, DigiNotar said on Tuesday that a July 19 attack on its certificate authority system resulted in forgeries being issued for “a number of domains” including Google's, but declined to specify the names or give a precise number. In a later interview with IDG News, a DigiNotar spokesman put the figure at “several dozen.”
The vacuum of information from DigiNotar has left researchers scrambling to figure out exactly how many sites might be affected. Exhibit A is the Chrome differential showing the number of “static const unsigned kNumSerials” equalling 257, compared to 10 in the previous version. The constant variable refers to the number of serial numbers enumerated in a list of blacklisted certificates.
Exhibit B is this list, compiled from DigiNotar's certificate revocation list. It shows that a little more than 100 certificates have been cancelled by the certificate authority since June.
It's impossible to say if all of Monday's changes to Chrome's “static const unsigned kNumSerials” involved certificates for separate web addresses. A Google spokesman didn't respond to an email asking for an explanation of the changes.
But the increase in serial numbers, combined with the comments “seem pretty indicative” that Chrome has purged hundreds of non-Google certificates issued by DigiNotar, said Andrew Storms, director of security operations at nCircle. ®