Microsoft has confirmed that an unpatched vulnerability in Internet Explorer was "one of the vectors used in targeted and sophisticated attacks targeted against Google and other corporate networks."

The cyberattacks, believed to have originated in China, prompted Google this week to say that it will no longer censor its Internet search results in the country, at risk of being forced out of the world's largest Internet market.

The company said in a statement that it "continues to work with Google, other industry partners and authorities to actively investigate this issue." It added, "To date, Microsoft has not seen widespread customer impact, rather only targeted and limited attacks exploiting IE 6."

In related news, Microsoft CEO Steve Ballmer told CNBC today that the company doesn't plan to follow Google's lead in China, and will continue operate there as it does now.

Ballmer reiterated the statement in an interview with Reuters. "We're attacked every day from all parts of the world and I think everybody else is too. We didn't see anything out of the ordinary," he told the news service. "There are attacks every day. I don't think there was anything unusual, so I don't understand," he told the news service.