The Global Positioning System (GPS) is a satellite-based navigation system made up of at least 24 satellites. These GPS satellites orbit the earth in a precisely defined and monitored orbit. Each GPS receiver measures the time it takes for each satellite’s signal to arrive, and the exact location of the receiver can then be calculated through multilateration.
GPS spoofing occurs when a radio transmitter (e.g., software defined radio, as shown in this demo) transmits a counterfeit GPS satellite signal that is stronger than the signal from the corresponding actual satellites. The GPS receiver will preferentially use the counterfeit signal, because it is stronger than the signal from the actual satellite. This counterfeit signal includes a false time base, which fools the GPS receiver into calculating that it is in a different location.
Why is spoofing an issue? Many applications, such as a ship’s navigation system, require precise location and/or precise time. For example, with just a laptop, a small antenna, and a GPS “spoofing” device, a group of college students fed a stronger signal to a yacht’s steering system than the genuine one from actual GPS satellites (article). By doing this, they essentially tricked the ship’s computer into believing it was somewhere it was not, causing it to adjust its heading to stay on course. A nefarious actor could do the same to cause a ship to collide with another ship or a known hazard, with disastrous consequences.
The cost of spoofing is hard to calculate. However, downtime of critical infrastructure that relies on an accurate location or time is a bigger issue than just a financial one. If spoofing goes undetected, applications that rely on location and time will produce inaccurate results or crash. Therefore, the detection of spoofing as soon as it occurs is paramount.
Click here to learn how SAS addressed this challenge using SAS ESP.