The attack is based on a security hole in a Windows DLL for rendering M HTML which has been known for some time. Google and Microsoft say they are working to solve the problem. Users advised to install a hot fix supplied by Microsoft which can block the attack until an official patch becomes available. Google also said that it has deployed various server-side defences to make the vulnerability harder to exploit. The company added that this is not a tenable long-term solution, and that it can’t be guaranteed to be fully reliable or comprehensive.
Source: https://thehackernews.com/2011/03/google-users-targeted-by-hackers.html