The third version of FairUse4M has a simple drag-and-drop interface. PC users can turn the protected music files they bought online -- either a la carte or as part of a subscription service like Napster -- and turn them into DRM-free tunes that can be copied and shared at will, or turned into MP3 files that can play on any type of digital music player.
"We knew at the start that no digital rights management technology is going to be impervious to circumvention," said Jonathan Usher, a director in Microsoft's consumer media technology group, in a phone interview.
Usher said Microsoft employs a full-time team to combat such breaches, and that the Windows Media DRM system was designed to be quickly modified to shut down this type of attack.
He did not say how many songs have been stripped of copy protection, or how long it will take for Microsoft to combat the hack again. But the music industry is aware of the nature of Microsoft's technology, he said, and added that he does not expect record labels to lose patience with the process.
The Recording Industry Association of America, a trade group, declined to comment.
While Usher said Microsoft will remain committed to copy protection, attitudes around the industry are starting to shift.
Apple has modified its own online store, iTunes, to block similar efforts to break its FairPlay copy protection scheme. But Apple's chief, Steve Jobs, started calling for an end to digital music-locking earlier this year.
"There are many smart people in the world, some with a lot of time on their hands, who love to discover such secrets and publish a way for everyone to get free (and stolen) music," Jobs wrote in an online essay in February. "They are often successful in doing just that, so any company trying to protect content using a DRM must frequently update it with new and harder to discover secrets. It is a cat-and-mouse game."
Apple's iTunes store started selling DRM-free music from EMI Group's catalog in May. The same month, Web retailer Amazon.com said its much-anticipated digital music store will sell tracks in the unprotected MP3 format.
Josh Bernoff, an industry analyst at Forrester Research, said he expects music DRM to fade out in the next couple of years as record companies begin to realize selling unprotected tracks online won't hurt sales. After all, Bernoff said, the same tracks are already circulating unprotected, copied from CDs and on file-sharing networks.