I also wonder with #spacepunk tech brewing if it's possible to actually overpower a satellites signal. There is someone on kickstarter working on low earth orbit satellites that would stay in orbit for 2 weeks.
As far as I know, all rockets are heavily regulated by the FAA, including have representatives at launch. I'd be willing to bet that an unauthorized launch wouldn't last very long.
Sure, but what are they going to do about it once it's up there?
The US, Russia, and China all have proven anti-satellite weapon systems. IIRC they are very similar to missiles designed to intercept ICBMs.
It would have to be a very irritating satellite indeed to justify the expenditure of hundreds of millions and loss of secrecy to those programs involved in shooting down a random satellite.
It might be easier to take over the satellite from the ground: