Professor Todd Humphreys and his team of students at University of Texas at Austin Radio-navigation Laboratory took up a challenge issued by the US Department of Homeland Security to take control of an unmanned commercial aircraft. With just about 1,000 dollars, the team was able to create a system that can “spoof” the GPS system on the drone. They repeatedly accessed the navigation system on the aircraft and were able to send a new series of command to divert the aircraft from its intended path. After a couple trips around Austin Stadium, the students put the craft into a nose dive before returning it safely back to land.
Jammers scramble GPS signals to and from the aircraft, but a spoofer mimics the signals being sent and can take control of the vehicle. This is done by creating a signal that is stronger than its source signal. Since commands are sent via satellite approximately 60 miles above the earth, it is not hard to create a device that can produce a signal to overpower it. The commercial drone is unaware that the signal source has changed and accepts its new commands freely. Since many of the signals from commercial drones and some from military drones are not encrypted, it is not very difficult to view data or take control of the vehicle.
Humphreys discussed the weaknesses of GPS controlled aircraft when Iran claimed to have taken control of a US military drone last year. While military level drones have a much higher level of security and encryption, they still have their faults. There are backup satellite signals that are much older and less secure that of the primary signals. It is possible to scramble or jam the primary encrypted signals and force the aircraft to use a less secure communication path to maintain safe travel and avoid accidental collisions. Other signals such as video feeds and images from the unmanned aircraft have no security at all. In 2008, video feeds were downloaded by insurgents in Iraq with readily available commercial software.
The US Air Force knew of the security risks as far back as 1996, well before unmanned aircraft became common place. The spoofing danger isn’t new. “On the military side,” says Humphreys, “they’ve known about this threat for 20-30 years.” While Humphreys doesn’t believe the Iranian claim of spoofing a military grade drone is true, he proved that commercial grade drones are another matter entirely. With the increasing pressure to open more U.S. airspace for GPS controlled drones, this challenge is exactly what is needed. Hurrying the legalization of unmanned aircraft without proper security could blanket the sky with miniature guided rockets. Many law enforcement and environmental agencies are eagerly awaiting the ability to launch their own aerial surveillance devices as are businesses that can use UAVs for video recording, security and crop dusting.