Researchers at the Horst Görtz Institute in Germany have developed a system to prevent hackers from manipulating GPS signals.
Currently, attackers can alter the GPS location data, received by satnav systems in cars for example, by using a satellite simulator.
GPS also has a number of industrial uses, such as the temporal synchronisation of machines, which could be brought to a standstill in the event of an attack.
Satellite simulators generate fake signals that appear authentic, and sends them out to receivers.
“This is how attackers can fool the receiver, which then assumes it is located in a different position than is actually the case,” explains Professor Christina Pöpper, who is leading the team developing a solution to the problem.
Their proposal involves the installation of multiple receivers in a vehicle, situated at a distance from each other, that are all receiving GPS data simultaneously.
If they receive genuine satellite signals, the receivers’ calculated positions differ slightly from each other.
However, if an attacker transmits signals using a simulator, they appear deceptively authentic and are identical for each individual receiver.
The attack can then be detected by comparing the individual receiver positions to each other, because now all the devices believe they are in the same wrong position.
This is because the relative reception times of several signals which are transmitted via the satellite simulator are identical in several receiver devices.
This is not the case when legitimate satellite signals are received, because they are transmitted from different positions in earth orbit.
“We have already demonstrated that this is how we can detect attacks,” says Pöpper. “At present, we are figuring out technical details. Details such as the minimum distance that is required between the receiver devices to make sure that they don’t identify their positions as identical when receiving authentic signals due to inaccuracies that will inevitably occur.”
According to the latest findings, the minimum distance between the devices should range between two and three metres. If the receivers are closer together, the error rate increases.
“This can be easily realised in large vehicles or machines, such as trucks or ships, because here the receivers can be positioned at a sufficiently great distance from each other,” says Pöpper. “A solution for mobile phones or other devices that are spatially restricted still needs to be found.”