Posted by Adam Langley, Security Engineer

On Wednesday, July 2, we became aware of unauthorized digital certificates for several Google domains. The certificates were issued by the National Informatics Centre (NIC) of India, which holds several intermediate CA certificates trusted by the Indian Controller of Certifying Authorities (India CCA).

The India CCA certificates are included in the Microsoft Root Store and thus are trusted by the vast majority of programs running on Windows, including Internet Explorer and Chrome. Firefox is not affected because it uses its own root store that doesn’t include these certificates.

We are not aware of any other root stores that include the India CCA certificates, thus Chrome on other operating systems, Chrome OS, Android, iOS and OS X are not affected. Additionally, Chrome on Windows would not have accepted the certificates for Google sites because of public-key pinning, although misissued certificates for other sites may exist.

We promptly alerted NIC, India CCA and Microsoft about the incident, and we blocked the misissued certificates in Chrome with a CRLSet push.

On July 3, India CCA informed us that they revoked all the NIC intermediate certificates, and another CRLSet push was performed to include that revocation.

Chrome users do not need to take any action to be protected by the CRLSet updates. We have no indication of widespread abuse and we are not suggesting that people change passwords.

At this time, India CCA is still investigating this incident. This event also highlights, again, that our Certificate Transparency project is critical for protecting the security of certificates in the future.

Update Jul 9: India CCA informed us of the results of their investigation on July 8. They reported that NIC’s issuance process was compromised and that only four certificates were misissued; the first on June 25. The four certificates provided included three for Google domains (one of which we were previously aware of) and one for Yahoo domains. However, we are also aware of misissued certificates not included in that set of four and can only conclude that the scope of the breach is unknown.

The intermediate CA certificates held by NIC were revoked on July 3, as noted above. But a root CA is responsible for all certificates issued under its authority. In light of this, in a future Chrome release, we will limit the India CCA root certificate to the following domains and subdomains thereof in order to protect users: