The good news about your scenario is that it requires a launch system capable of putting those objects in orbit. A small rocket would orbit only a few objects, so you'd need either a large rocket or many small ones.

This would restrict this technique to those nations that have such rockets. It goes without saying that such a rocket is also functional as an ICBM, so even if they didn't throw BBs into orbit, a rogue nation with such rockets is already a problem.

Another terror attack method I have worried about for satellites (and space stations) in low earth orbit would be to fire a rocket filled with shrapnel and explosives to the altitude of the satellite, and directly in its path. The bomb would explode and blow shrapnel into a large cloud of metal that the target would strike at orbital velocity relative to the cloud. There would be no way to avoid it, and the orbital parameters of satellites and the ISS are public knowledge.

This is a much easier mission from a propulsion standpoint since it requires only a rocket capable of flying straight up to a couple of hundred miles (ISS altitude is around 250 miles), and does not need to attain orbital velocity. There are LOTS of rockets that can do this. An old V-2 could make it to over a hundred miles.

Fortunately, the guidance problem is not a trivial one, and may be beyond most terrorists. The cloud of metal is not in orbit, but just in space. It will immediately begin to fall back to Earth after the detonation, so the launch, flight and detonation would have to be timed to the second, or the passing target will miss the cloud.