They're illegal thanks to crash testing and emissions.
Anything since keyfob remotes were added is suspect. How many of these already have a killswitch built in? If it receives data it might be hackable. The special message just needs to be long enough that noise and interference will not trigger it in any practical time window (decades * millions of vehicles). While cars have had a stereo for a long time, the radio, until recently, had a completely analog audio path and there was no signal path from the radio to control anything in the car.
They're illegal thanks to crash testing and emissions.
Anything since keyfob remotes were added is suspect. How many of these already have a killswitch built in? If it receives data it might be hackable. The special message just needs to be long enough that noise and interference will not trigger it in any practical time window (decades * millions of vehicles). While cars have had a stereo for a long time, the radio, until recently, had a completely analog audio path and there was no signal path from the radio to control anything in the car.
Good point!