An anonymous reader writes: Microsoft is using the IP address 'voluntarily' collected during its software activation process to sue a Comcast subscriber for pirating thousands of copies of Windows and Office. The Redmond giant wants the court to issue a subpoena which will force Comcast to hand over the pirating subscriber's info. If the infringing IP address belongs to another ISP which obtained it via Comcast, then Microsoft wants that ISP's info and the right to subpoena it as well. "Defendants activated and attempted to activate at least several thousand copies of Microsoft software, much of which was pirated and unlicensed," Microsoft's legal team wrote. The product keys "known to have been stolen" from Microsoft's supply chain were used to activate Windows 8, Windows 7, Office 2010, Windows Server 2012 and Windows Server 2008. The product keys, Microsoft said, were used "more times than is authorized by the applicable software license," used by "someone other than the authorized licensee," or were "activated outside the region for which they were intended." Whether or not the IP traces back to a Comcast subscriber or was assigned by Comcast to a different ISP, as the The Register pointed out, "It would be a significant gaffe on behalf of the alleged pirates if the IP address data pointed to their real identifies."