Anything free is cool, but getting a fully upgraded operating system for the great price of nothing is downright awesome. A recent exploit was uncovered that allows users to get a free copy of Windows 8 Pro directly from Microsoft’s own website. Seriously.

As I wrote in an earlier article, the native media player for Windows, Windows Media Center, was removed from Windows 8. In order for people to get Windows Media Center, they would need to pay for it starting January 31st, 2013. Until then, you can download it for free with Microsoft’s special offering.

But a nice little side effect takes place—by using the upgrade, it permanently activates the copy of Windows 8 that you’ve applied it to.

And this is good news for pirates, thanks to Microsoft’s weak Key Management Service (KMS). ZDNet has a good explanation of how KMS works:

Built for enterprise users, the KMS is intended to make deployment of Windows 8 through a KMS host and KMS client, making Windows 8 fully usable for 180 days before activation. In other words, instead of being required to input an activation key or reach Microsoft authentication channels on each individual computer, businesses can activate Windows copies on a local network and make the transition step-by-step.

Now, using this little workaround, people can swap KMS Client Setup Keys (like the ones listed on Microsoft’s site) to snag a fully activated free copy of Windows 8 Pro using the Pro Pack upgrade key.

Anyone who has installed a pirated version of Windows 8 Pro, can input the key received for the Windows Media Player Upgrade, which will then install onto your system making the Windows 8 Pro permanent, removing the need to purchase after 180 days.

You can find more information on Reddit, where this trick first appeared.

It has been verified as working for now, but who knows how long this will last (or how long the installation will be able to pass the windows Genuine Advantage verification test).