Microsoft has responed to an application that threaded to remove the DRM encoding from Windows Media Files, and released a security patch. Enthusiasts website Engadget.com had reported on a small utility called FairUse4WM able to remove DRM information from WMA files to allow playback on any device.

FairUse4WM could be used to strip Windows Media DRM 10 and 11 (i.e. PlaysForSure, but not WM DRM 9). For example, providers like Napster and Yahoo Music Unlimited provide subscription service for unlimited access to Windows Media DRMed files. Using the FairUse4WM utility would make Napster To Go tracks freely available to play on Macs. In other words, the method made audio files playable even after users were no longer paying subscription fees.

The new update from Microsoft updates the individualized blackbox component (IBX) that exists in PlayForSure. The update was released on Monday and content service providers received an email from Microsoft advising to install the update.