A May 18th Washing Post article by about Chris Roberts, the security researcher questioned by the FBI about monkeying with planes’ avionics via the entertainment system, caught my attention. Not because of the sensational headlines, but because of a sentence attributed to “other aviation and security experts.”
In an attempt to make it seem that it is very unlikely to access the avionics from the entertainment system, the article states that “hacking a plane’s engine controls through its entertainment system, they argue, is a bit like controlling a car’s steering wheel through its CD player.” Unfortunately, it is quite possible to control a car’s steering wheel through its CD player. This is due to the electric power steering assistance used on most new cars, and the fact that the CD player and power steering are often both on the CAN bus.
The fact that the CD player in modern vehicles is both often on the CAN bus and hackable is widely known. Noted security expert Bruce Schneier wrote about this topic in 2011. And, of course, once you have access to the CAN bus, you can control other things connected to it such as the electric power steering assistance.
As an example, we can take the modern Ford Mustang. From at least the 2012 model, the power steering has had 3 modes select-able via the instrument cluster screens which are driven by the CAN bus. (See “STEERING FEEL” on page 22 of the owner’s manual.) The CD player is also on the CAN bus, as that is where it gets the dimmer signal. Thus, if you were to hack the CD player, you could then use the CAN bus to control the steering.
In conclusion, I certainly hope that controlling a plane’s avionics via the entertainment system is more difficult than controlling a car’s steering via the CD player.