Microsoft this week released a warning about another flaw in its Internet Information Services web server software, and warned Windows XP's indexing service may also be affected. IIS is built into Windows NT, 2000 and XP, Microsoft's next generation of operating systems.
Redmond's bloatware behemoth said a "serious vulnerability" in the IIS software could allow hackers to terrorise computers and vandalise online sites.
"Clearly, this is a serious vulnerability and Microsoft urges all customers to take action immediately," says the advisory report. "Microsoft strongly advises all web server administrators to apply the patch immediately."
This is more bad news for Microsoft, which has been battling stubborn glitches for more than a month.
Microsoft estimates around six million users could be affected and urges all users to download the safety patch as soon as possible, from Microsoft's site.
The problem affects all versions of IIS running on Windows NT, 2000 or beta versions of XP, allowing hackers to gain access via a bug in file idq.dll while the user is online and to then gain complete control of the user's computer.
IIS is the built-in web server component that started out inside NT and became standard in Microsoft's web servers running on later systems – 2000 and XP.