Microsoft admits Explorer used in Google China hack

The firm said in a blog post on Thursday that a vulnerability in the browser could allow hackers to remotely run programs on infected machines.

Following the attack, Google threatened to end its operations in China.

Microsoft has released preliminary guidance to mitigate the problem and is working on a formal software update.

So far, Microsoft "has not seen widespread customer impact, rather only targeted and limited attacks exploiting Internet Explorer 6".

"Based upon our investigations, we have determined that Internet Explorer was one of the vectors used in targeted and sophisticated attacks against Google and possibly other corporate networks," said Microsoft's director of security response Mike Reavey in the post.

Security firm McAfee told news agency AFP that the attacks on Google, which targeted Chinese human rights activists worldwide, showed a level of sophistication above that of typical, isolated cyber criminal efforts.