Microsoft said Tuesday it is working around the clock to patch an Internet Explorer 6 (IE 6) software hole through which China-based cyber spies attacked Google and other firms.
Microsoft is testing a security fix and will make it available as soon as it is ready instead of following its protocol of releasing security updates the second Tuesday of each month.
"We are working 24-by-7, around the clock," Microsoft general manager of Trustworthy Computing Security George Stathakopoulos told AFP. "We have been monitoring the threat landscape since the start of this issue."
Microsoft is to announce Wednesday when the security patch will be released.
Attacks that prompted a showdown between Internet giant Google and global power China only worked against IE 6, so computer users can protect themselves by switching to newer versions of the Web browser, according to Stathakopoulos.
"IE 7 and 8 seem to be holding," Stathakopoulos said. "None of the attacks we know of will be effective against IE 8. That could change, but that is what we know."
No matter which Web browser people use, upgrading to the most current version promises to increase protection against hackers.
Microsoft confirmed last week that a previously unknown security vulnerability in its IE 6 browser was used in cyberattacks which prompted Google to threaten to shut down its operations in China.
Revealing the attacks on January 12, Google said they originated from China and targeted the email accounts of Chinese human rights activists around the world but did not explicitly accuse the Chinese government of responsibility.
Web security firm McAfee Inc. said that the attacks on Google and other companies showed a level of sophistication beyond that of cyber criminals and more typical of a nation-state.
Dmitri Alperovitch, vice president of threat research for McAfee, said that while McAfee had "no proof that the Chinese are behind this particular attack, I think there are indications though that a nation-state is behind it."
Google said more than 20 other unidentified firms were targeted in the "highly sophisticated" attacks while other reports have put the number of companies attacked at more than 30.
Stathakopoulos described the attacks as "limited and targeted."
Only one other company, Adobe, has come forward so far and acknowledged that it was a target.
Attackers used email or some other lure to get employees of a targeted company to click on a link and visit a specially crafted website using Internet Explorer, Alperovitch said.
Malicious software would then be downloaded that has the capability to essentially install 'back doors' in machines and give hackers access, according to McAfee.
Explore further: Microsoft releases security patch for Web browser