Just like driver-less cars, anything autonomous is prone to getting hacked and misused...
Here is a good piece on it: "SECURING DRIVERLESS CARS FROM HACKERS IS HARD" - https://www.wired.com/2017/04/ubers-former-top-hacker-securing-autonomous-cars-really-hard-problem/
It is very difficult and the race to produce autonomous vehicles is pushing the challenge even higher.