Microsoft has issued a security patch to fix a critical vulnerability in its Internet Explorer browser it said has attacked over 2m Windows users.
The flaw is believed to have already infected as many as 10,000 websites.
The “zero day” exploit let criminals take over victims’ computers by steering them to infected websites.
Microsoft’s Christopher Budd said the software giant “encourages all IE customers to test and deploy this update as soon as possible”.
He also said the threat lead Microsoft to mobilize security engineering teams worldwide to deliver a software cure “in the unprecedented time of eight days”.
The company’s security response team said the patch consists of more than 300 distinct updates for more than half-a-dozen versions of IE in around 50 languages.
“Even with that, the release Emergency Response process isn’t over,” said Security Response Alliance director Mike Reavey.
“There is additional support to customers and additional refinement of our product development efforts.”
Microsoft stressed that the flaw was proven to exist only in IE 7 on all applicable versions of Windows, but that IE 6 and the “beta” release of IE 8 were “potentially vulnerable”.
Users who have automatic updates turned on will receive the patch over the next 24 hours while others can access it via a download.
The AZN Trojan has been making the rounds since the beginning of December but became public knowledge in the last week . Unlike other exploits, users only have to visit a malicious site with Trojans or other malware in order to become contaminated.
The update is something of an unusual move for Microsoft and underscores the seriousness of the zero day flaw.
The company rarely issues security fixes for its software outside of its regular monthly patch updates.
Meanwhile Mozilla has released a scheduled update for its open source Firefox web browsers for at least 10 different vulnerabilities.
The bugs in the browser could have been “used to run attacker code and install software, requiring no user interaction beyond normal browsing,” said Mozilla.
It is also reissuing calls for users to upgrade from Firefox 2.0 to Firefox 3.0 as soon as possible and said it is “not planning any further security and stability updates for Firefox 2”.
This means Mozilla will no longer support the Firefox 2 browser against future online scams and attacks.
Source: BBC News – http://news.bbc.co.uk/1/hi/technology/7788687.stm