Microsoft has quietly seeded an update which removes or replaces files which allow pirated copies of the operating system to work.
The anti hack detection update has already been rolled out to anyone using the company's automated Windows Update software, but users monitoring their own updates will spot the KB971033 update listed among all the other fixes and patches.
The update explains, "This update for Windows Activation Technologies helps detect validation errors and activation exploits. This update also detects any tampering attempts made to important Windows 7 system files. Be aware that some counterfeit copies of Windows include malware. When this update is installed, it performs a validation process for the copy of Windows that is running on your computer. However, this validation process does not affect the functionality of Windows. The update process exits silently if it detects no validation errors, activation exploits, or tampered files."
If the update finds any dubious hacked files it will send you off to a Microsoft website for a stern lesson in the benefits of paying for your software.
Techarp reports that the update cannot be removed or rolled back which would mean a fresh install is required.