Not a feat for everybody, but hacking satellites either connecting directly to them or by intrusion on the ground computers that manage them, could have dire consequences: from shutting them down, to burning them in space, spiralling them to ground or turning them into ballistic weapons.

Even if news have not been really confirmed and details are sketchy, it seems that some incidents already happened, starting from 1998, see the ROSAT satellite history, and more recent events as described here, here, here and here for a recent review.

Independently from the confirmation of the incidents, controlling by remote satellites, in particular small ones built also with off-the-shelves / commodity components, coupled with the difficulty (if not impossibility) of applying security patches, can make their “Cybersecurity” risks quite relevant, and effective counter-measures quite difficult. On the other side, due to the costs of building and sending a satellite in space, it is likely that these “Cybersecurity” risks are considered and effectively managed in the planning and developing phases of a satellite life-cycle, or at least so we hope.