A security hole in Microsoft\ufffds Internet Explorer could prove devastating.

Following the exposure of a vulnerability in Windows XP earlier this week, \ufffdhttp-equiv\ufffd of Malware has revealed that Explorer 6 users (and possibly users of earlier versions) could be fooled into downloading what look like safe files but are in fact whatever the author wishes them to be - including executables.

A demonstration of the hole is currently on security company Secunia\ufffds website and demonstrates that if you click on a link, and select \ufffdOpen\ufffd it purports to be downloading a pdf file whereas in fact it is an HTML executable file.

It is therefore only a matter of imagination in getting people to freely download what could be an extremely dangerous worm - like, for instance, the Doom worm currently reeking havoc across the globe.

However what is more worrying is that this hole could easily be combined with another Explorer spoofing problem discovered in December.

The previous spoofing problem allowed Explorer users to think they were visiting one site when in fact they were visiting somewhere entirely different. The implications are not only troublesome, but Microsoft\ufffds failure to include a fix for the problem in its January patches has led many to believe it cannot be prevented.

If the same is true for this spoofing issue, then it will only be a matter of time before someone who thinks they are visiting one website and downloading one file will in fact be visiting somewhere entirely different and downloading whatever that site\ufffds owner decides.