The Redmond, Wash., software maker did not say when it would deploy the fix that counters the FairUse4WM application.
"We have an update to address the circumvention and are working with our partners to deploy this solution," Marcus Matthias, senior product manager for the Windows Client Division, said in an e-mailed statement.
Those partners include providers of music and video that depend on Microsoft's digital rights management technology to prevent illegal copying of their content. FairUse4WM, released anonymously on the Web more than a week ago, provides a graphical user interface for the DRM removal program called "drmdbg," simplifying the process of running files through the application.
The new tool works only on music files containing DRM technology from versions 10 and 11 of Windows Media player. The application can only work on one file at a time.