Researchers who have spent the last two years studying the security of car computer systems have revealed that they can take control of vehicles wirelessly.

The researchers were able to control everything from the car's brakes to its door locks to its computerized dashboard displays by accessing the onboard computer through GM's OnStar and Ford's Sync, as well as through the Bluetooth connections intended for making hands-free phone calls. They presented their findings this week to the National Academies Committee on Electronic Vehicle Controls and Unintended Acceleration, which was brought together partly in response to last year's scandal over supposed problems with the computerized braking systems in Toyota Priuses.

The team, including Tadayoshi Kohno, an assistant professor of computer science at the University of Washington, and Stefan Savage, a professor of computer science at the University of California, San Diego, had previously shown that they could take control of a car's computer systems, provided that they had physical access to the vehicle's onboard diagnostics port—a federally mandated access point located under the dashboard in almost all modern cars.

With the new work, the researchers systematically analyzed ways they could get at a car's computer systems without having physical access. They used a 2009 mass-production sedan equipped with fewer computer systems than many high-end cars. For each attack that succeeded, they confirmed that they could take complete control of all of the car's internal computer systems.

The researchers attacked the car's Bluetooth system, which allows a driver to make hands-free cell-phone calls. They found a vulnerability in the way the Bluetooth system was implemented that allowed them to execute code to take control of the car. To do this, the researchers used a smart phone already paired with the car or found a way to illicitly authorize a new smart-phone connection.

Nowadays many cars come equipped with cellular connections that perform safety functions, such as automatically calling for help if the driver is in a crash. The researchers found that they could take control of this system by breaking through its authentication system. First, they made about 130 calls to the car to gain access, and then they uploaded code using 14 seconds of audio. The researchers also found other ways to gain access, for example via the car's media player.

"We were surprised to find that the attack surface was so broad," Kohno says, referring to the wide variety of ways the researchers were able to gain access to the car's computer systems.

The team analyzed possible attack scenarios as well. For example, they showed that high-tech car thieves could search for desired models of cars, identify their locations, and unlock them, all without any forced entry. They could conduct malicious surveillance, such as forcing a car to send out its GPS location at regular intervals. They could also sabotage a car, by disabling its brakes, for example.