Researchers at the University of California at San Diego and the University of Washington found a way to hack OnStar computers and take almost total control of GM vehicles. The research team privately disclosed the results to the National Highway Traffic and Safety Administration and to GM, yet it took the motor company nearly five years to fully protect vehicles from the hacking technique.
Koscher was able to connect to an OnStar system through Verizon's voice network and reached an audio tone that the computer played. Koscher reverse engineered the sound and was able to create an mp3 file that could overflow the computer with data when it heard the tone.
GM tried multiple times to fix the hack, but measures failed due to technical issues between Verizon networks and OnStar computers.