Given how paranoid the Russians were about the Space Shuttle (they suspected it could take the entire abandoned Salyut V station into its cargo bay, "steal it" and return to the US with it so that enemy scientists could study it), they almost certainly have routines to destroy sensitive payloads and data at a distance.

Also, just changing the orbit so that the perigee is sufficiently low (say, 200 km) will basically ensure complete burnup of the satellite in a matter of weeks. Atmospheric drag is a significant force on the lower orbits and what matters is the perigee, where the remnants of the atmosphere are densest. They will act as a powerful brake.