In 2016, more than 20 ships off the Crimean peninsula appeared to be hit by a GPS spoofing attack. Their positions on electronic charts jumped onto land. Three years later, GPS reception dropped across Israeli ports as collateral damage from the Syrian civil war, and GPS-guided autonomous cranes stopped working. EE Times, in an April 2021 report by Nitin Dahad, used those incidents to show why engineers were hunting for ways to protect satellite navigation.
Two attacks, one weak signal
The problem starts with the signal itself. GPS and other satellite navigation signals are weak by the time they reach the ground, so a small transmitter on the same frequency band can swamp them. That is jamming. Typical jammers are cheap, and they do not discriminate, EE Times noted: air traffic control, search and rescue, the electric grid and mobile phone services can all suffer fallout.
Spoofing is subtler. The attacker broadcasts signals that imitate the real ones but carry false location information, so a receiver believes it is somewhere else in space or time. The outlet said spoofers can hijack autonomous vehicles, alter routes recorded by vehicle monitors and break geofences. Jan van Hees of receiver maker Septentrio gave the analogy: jamming is so much noise that the satellite signal disappears, while spoofing “is like a phishing attack on the signal.”
Criminals use jammers too. Guy Buesnel, a GNSS vulnerability specialist at Spirent Communications, pointed to an FBI bulletin from 2014 on jammers used to hide stolen luxury cars and fully loaded shipping containers.
The numbers behind the worry
Following jamming incidents over Norway that likely came from nearby Russia, the European aviation agency Eurocontrol reported a 2,000-percent rise in GNSS interference incidents since 2018. Most interference hotspots sit in conflict zones, but the effects reach civil aviation at distances of up to 300 km. One report cited by Buesnel put the economic cost to the U.K. of a complete GNSS loss at £5.2bn over five days. The U.S. Maritime Administration had also issued a warning the year before, urging industry to use alternative navigation systems.
What was being built in response
Europe’s answer was OSNMA, a service that authenticates the navigation data from Galileo satellites using a digital signature and a secret key on the satellite. Test signals were already broadcasting, with eight satellites in the first round in November, and the service was due to be free. Rod Bryant of U-Blox warned of a weak point: “If you are a clever spoofer, you could delay your signals to capture the key.”
For GPS, the proposed Chimera system would embed encrypted digital signatures and watermarks in the civilian signal. It was still in early testing.
In the U.S., NIST had released final cybersecurity guidance for positioning, navigation and timing services, and the Department of Homeland Security offered free tools, a PNT integrity library and the Epsilon algorithm suite, to check GPS data. Space Policy Directive-7 told GPS users to plan for signal loss. Jim Platt of the Cybersecurity and Infrastructure Security Agency’s National Risk Management Center put it plainly: critical infrastructure should not assume GPS data will always be available or accurate.
