This makes things all the more creepier, as it shows that the hacker himself or herself does not even need to be physically present on the plane to do so. How did Teso perform this seemingly impossible task? Well, he exploited the Aircraft Communications Addressing and Report System (ACARS), which so happens to control the plane’s flight management systems, and lacks a whole lot in terms of security.
Teso said, “You can use this system to modify approximately everything related to the navigation of the plane. That includes a lot of nasty things. ACARS has no security at all. The airplane has no means to know if the messages it receives are valid or not, so they accept them and you can use them to upload data to the airplane that triggers these vulnerabilities. And then it’s game over.”
Update: The FAA has dismissed this “hack”, and you can read all about it here.