Microsoft Corp on Thursday released a patch to protect users of its Internet Explorer browser from attacks similar to those directed at Google Inc’s operations in China last week.

The world’s largest software company, which said hackers targeting Google and at least 20 other companies in China exploited a weakness in its browser, said its new patch was “critical” and people should apply it as soon as possible.

Other hackers have begun to exploit the flaw, according to researchers with Symantec Corp, the world's biggest security software maker.

Symantec has found viruses that take advantage of the weakness in Microsoft’s browser on some 100 websites, security researcher John Harrison said on Thursday.

They are dangerous because they can infect the PC of any user who visits those sites. Unlike less powerful viruses, it is not necessary for people to download software for their machines to become infected, Harrison said.

PCs are safe if they apply the patch, which resolves eight vulnerabilities in Internet Explorer, Microsoft said. The most serious could allow hackers to gain control of a computer remotely via Web sites people visit while using the browser.

via Microsoft issues emergency Google attack patch | Reuters.