Hackers have released software that could be used to take over Windows PCs that lack the latest Microsoft security patches. But while this code is dangerous, security experts said Friday that it had yet to be used by attackers in any widespread way.

The attack code exploits two separate bugs in Windows Media Player, which were addressed in Microsoft's MS06-005 and MS06-006 advisories released Tuesday.

The MS06-005 bug concerns a flaw in the way the Media Player processes bitmap files, while MS06-006 has to do with the Media Player plug in for non-Microsoft browsers.

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."

So far, none of the code is being used much by attackers, he added. "Clearly there's been activity on the exploit-code writing side, but we haven't seen that translate into impacting customers."

Another security researcher agreed with Schmugar's assessment. "Yesterday we got a lot of reports of [the code] being used, but they turned out to be false positives," said Johannes Ullrich, chief technology officer of the SANS Internet Storm Center. "I haven't seen anything really used in the wild."