August 29, 2011
An update on attempted man-in-the-middle attacks
Today we received reports of attempted SSL man-in-the-middle (MITM) attacks against Google users, whereby someone tried to get between them and encrypted Google services. The people affected were primarily located in Iran. The attacker used a fraudulent SSL certificate issued by DigiNotar, a root certificate authority that should not issue certificates for Google (and has since revoked it).
Google Chrome users were protected from this attack because Chrome was able to detect the fraudulent certificate.
To further protect the safety and privacy of our users, we plan to disable the DigiNotar certificate authority in Chrome while investigations continue. Mozilla also moved quickly to protect its users. This means that Chrome and Firefox users will receive alerts if they try to visit websites that use DigiNotar certificates. Microsoft also has taken prompt action.
To help deter unwanted surveillance, we recommend that users, especially those in Iran, keep their web browsers and operating systems up to date and pay attention to web browser security warnings.
Update Aug 30: Added information about Microsoft's response.
Update Sept 3: Our top priority is to protect the privacy and security of our users. Based on the findings and decision of the Dutch government, as well as conversations with other browser makers, we have decided to reject all of the Certificate Authorities operated by DigiNotar. We encourage DigiNotar to provide a complete analysis of the situation.