Microsoft has released automated workarounds designed to immunize users against a critical vulnerability in earlier versions of Internet Explorer, which criminals are already exploiting online.

The "Fix It" updates were released over the weekend for people who still use IE versions 6 and 7: http://support.microsoft.com/kb/981374
The fixes are by no means foolproof. One of them disables the so-called peer factory functionality the browser may need to carry out certain tasks, such as printing. The other turns on a measure known as DEP, or data execution prevention, on more recent operating systems.

The releases are meant to serve as temporary fixes until an update is offered that patches the hole. Microsoft disclosed the vulnerability last week and warned that crooks are already using it to remotely execute malicious code on customers' computers.

A Microsoft communications manager said on Friday that engineers were busy developing and testing the patch, but he didn't say whether the company would issue it on the second Tuesday in April, during the next scheduled update release, or publish it out-of-band.

All the fuss about this vulnerability airs one of the industry's sadder facts: Much of it remains unwilling or unable to upgrade to the latest version of IE. Microsoft has expended considerable resources to insulate it from the most common forms of attack. Besides being immune to the attacks disclosed last week, it is also also safe from a separate remote-code execution bug that was recently disclosed. Google, Adobe, and other companies hit in the recent "Aurora" attacks were vulnerable because their employees continued to use IE 6.

Shops and homes that can should immediately upgrade to IE 8. Those that can't should check out the temporary fixes, but don't say you weren't warned.

(Register)