How many times does it have to be said that it is not necessarily stolen.
If the cable companies throw them away or do not want to collect them & advise their customers to throw them away (and they have done) then once it has been done it can then legally be "owned" by someone else.
But it's most likely just a useless unit unless illegal means are used to get it working.
see
here and
here for previous threads on this sort of spare box.
in essence it's useless to you for legal reception.