An interesting article....
Hacker Demonstrates Remote Plane Hijacking Using Android App
http://www.pcmag.com/article2/0,2817,2417668,00.asp
"Using the application, dubbed PlaneSploit, Teso demonstrated how to virtually hijack flight desk computers and feed false navigation information to change the course of a simulated jet, according to Help Net Security, which sat in on Teso's presentation at the Hack in the Box security conference in Amsterdam... What he found was a terrifying ability to make flying machines "dance to his tune," as Help Net Security noted."
Not quite as scary as it sounds at first:
"This presentation was based on a PC training simulator and did not reveal potential vulnerabilities on actual flying systems," an EASA statement said. "There are major differences between a PC based training FMs [flight management system] software and an embedded FMS software.....The version Teso used does not include the same overwriting protection and redundancies that certified flight software does, the agency said....The FAA agreed, saying in a statement that it has "determined that the hacking technique described ... does not pose a flight safety concern because it does not work on certified flight hardware."