Hackers have released malware which could be used to take over Windows PCs that lack the latest Microsoft security patches, utilising two separate bugs in Windows Media Player (addressed by Microsoft in Microsoft's MS06-005 and MS06-006 advisories.) The MS06-005 bug is to do with how Media Player processes bitmap files; MS06-006 has to do with the Media Player plug in for non-Microsoft browsers. Both could be used by a remote attacker to seize control of an unpatched machine.

Of these two bugs, Microsoft rated only MS06-05 as critical, but both could be exploited to seize control of an unpatched machine, according to the French Security Incident Response Team website, which has published examples of the malicious code.

In fact, the code that takes advantage of the MS06-006 flaw may be of greater concern to Windows users, said Craig Schmugar, virus research manager with McAfee's Avert Labs. "From a vulnerability side, MS06-005 is a concern, but from what we've seen so far, the MS06-006 exploits are further along."