Originally Posted by
Rumblefish
There was something like this with Windows Vista serial numbers.
Since the algorithm for their generation is known, a program was released that tried to activate your Windows key with Microsoft's servers over and over again until it hits a legit unused key in their database and then you got an activated, legit copy of Windows Vista with a genuine key.
They fixed it fast enough, though and now it won't work anymore.
Bottom line is this is not just plausible,
Obviously, these things do exist, but they will always be kept private.