In late August, hackers released a program called FairUse4WM, which lets Windows Media Player (WMP) users decrypt music files purchased online and reformat them into unprotected Windows Media Audio (WMA) files. Microsoft then patched its server-based components so that content makers could require users to upgrade their clients to a WMP version that circumvents FairUse4WM. But the hackers quickly struck back with a new version of FairUse4WM that bypasses Microsoft's efforts.

After the release of the original FairUse4WM, I contacted a Microsoft representative, who told me that the hack was indeed real and not just an analog hole-based circumvention. (Such hacks require users to manually play each protected song to record unprotected versions one at a time, but don't actually compromise the integrity of the underlying protection technology.) In a letter to Windows Media licensees soon thereafter, Microsoft said it would update its individualized blackbox component (IBX) to circumvent FairUse4WM.

"Consumers are not at risk in any way," the company told licensees. "Content services can require that the updates be present in order to issue licenses \[to consumers\]." The IBX update is particularly important to subscription-based services such as Napster and MTV URGE, because users of those services can downloads thousands of tracks at a time for a monthly fee. By requiring users to upgrade to a new license, these services can halt the flow of music that can be unencrypted and freely copied.

However, on September 2, hackers released a new version of FairUse4WM that bypassed Microsoft's changes and added support for different WMP versions, including the new WMP 11 Beta 2. What's interesting about FairUse4WM is that it decrypts only music you've purchased yourself: The tool won't work unless you have a valid license for the content on the PC to which you've installed FairUse4WM.

Questions remain, of course. Does FairUse4WM represent fair use of purchased (not subscription) content, in a legal sense? Although the use appears to be legal, users agree to certain conditions when they purchase media via online services. Those conditions include prohibitions against circumventing the Digital Rights Management (DRM) technology that prevents users from copying tracks.

FairUse4WM users should be concerned that Microsoft will ultimately defeat FairUse4WM. The company is sure to release yet another IBX patch. Ultimately, Microsoft has far more at stake than the hackers responsible for FairUse4WM. My guess is that Microsoft will shut FairUse4WM down pretty quickly.