With Microsoft saying that it may wait until April 11 to patch a critical vulnerability in its Internet Explorer (IE) browser, security vendor eEye Digital Security has released what it calls a "temporary" patch to address the problem.
The bug, which concerns the way IE processes Web pages using the createTextRange() method, is now being exploited by attackers on hundreds of malicious websites. Users who might be tricked into visiting these websites could have unauthorised software installed on their computers, according to security experts.
Though Microsoft has described these attacks as limited, in scope, the problem is being taken seriously by the software giant because the exploits can be used to seize control of a users machine.
"We are working day and night on development of a cumulative security update for Internet Explorer that addresses the vulnerability," head of Microsoft's Security Response Center, Stephen Toulouse, said in a blog posting.
This patch was expected to be released as part of an April 11 security update, although the software could come earlier if the threat grows, Toulouse said.
The possibility that it could be more than two weeks before the bug was fixed prompted eEye to release the patch, the security company's chief hacking officer, Marc Maiffret, said. "That's a long time to leave several million Windows users without any sort of protection," he said.
Microsoft said that users could avoid the attack by disabling Active Scripting in their browsers, but this was not a viable option for the many users who used sites that employed scripting, Maiffret said.
EEye's patch, which is available free of charge, will automatically remove itself when Microsoft's official patch is delivered. It can be downloaded at http://www.eeye.com/html/research/alerts/AL20060324.html
Determina released a second IE patch addressing the same problem. That patch, which is also available for free, can be found at "http://www.determina.com/security_center/security_advisories/securityadvisory_march272006_1.asp.
This not the first time security researchers have rushed to patch IE ahead of Microsoft. In late December, Ilfak Guilfanov, a developer with Liege Belgium's DataRescue SA, wrote a widely-distributed patch that fixed a similarly critical bug in Internet Explorer.