A University of Texas researcher who has hacked the navigational systems of drones and ships told PBS on Friday that anyone with his software could do the same.

"You know, we had done experiments in our laboratory and we'd convinced ourselves that we could hack a GPS receiver, make it believe it's some other place, but what does this mean?" Professor Todd Humphreys said. "What does it entail? Could you, for example, remotely and clandestinely lead an expensive and enormous ship at sea off course without the crew even knowing? That was the question we sought to answer, and it turns out the answer is yes."

Humphrey's and and his graduate students used a technique called "GPS spoofing," in which false GPS signals are broadcast that trick a vehicle's GPS receiver. The researchers first used the technique to commandeer an aerial drone. More recently, they commandeered a ship.

Milton Clary of Overlook Systems Technologies told PBS that spoofing attacks posed a huge threat.

"If GPS goes away or it gets spoofed, that could be very disruptive," he explained. "All our ground transportation, water transportation, rail transportation, positive train control, which is a very important thing to the Federal Railway Administration -- want to know where these trains are and where they are in time."

Watch video, uploaded to YouTube by PBS, below: