GPS jamming and spoofing - the threat

There are basically two ways to manipulate GNSS receivers. The first is jamming, where the receivers are exposed to electromagnetic interference at the frequencies used by the GNSS satellites. If jamming blocks GNSS receivers tracking goods, freight containers, vehicles, even pets, and virtually anything else, can disappear from their owners' dashboards, either temporarily - just long enough to hide some form of unlawful behaviour - or permanently. GNSS jammers are easily available online for less than $30.

Then there is the spoofing, in which GNSS receivers are deceived by feeding fake satellite signals, for example, for a different time or place. In some cases, spoofing attempts may be detected immediately by the GNSS receiver or by the user. But if the goal is to make GNSS unreliable in a particular region, it will sooner or later succeed.  

Using spoofing to drive a vehicle to a wrong destination without the driver noticing it sounds more like a James Bond movie. But last year, a team of researchers from the US and China developed a sophisticated spoofing device that achieved just that. By faking the satellite signal in just the right circumstances, they were able to get the car's navigation system to generate a new route to a "wrong" destination.

The researchers' trick went like this: The navigation instructions continued to match the actual outside environment of the car, while fake GNSS signals played to the navigation device that it was still on the way to the original destination. The researchers tested their device to 40 participants. Of those, 38 drove all the way to the wrong destination. The hardware needed was only $223.

With a wide range of economies relying on GNSS technology - including in sensitive areas such as banking and aerospace - jamming and spoofing could potentially be used as an effective weapon, as a kind of "weapon of mass disruption." Human users may recognise obvious discrepancies between GNSS data and reality. However, since automated systems lack this human filter, these systems using GNSS data are particularly vulnerable 

Immunise the recipient against spoofing
Being aware of the danger is a crucial first step in dealing with the threat of jamming and spoofing signals. Owners of goods can take immediate action if they discover that their asset trackers are blocked for some reason. Fortunately, it is quite easy for a GNSS receiver to detect jamming. In the best case, the tracking application informs the owners of the goods that something questionable is in progress.

In addition, modern GNSS receivers can track multiple GNSS constellations and frequency bands simultaneously. But then significantly more signals would have to be manipulated in parallel, so that the spoofing goes unnoticed. And Galileo, the European GNSS constellation, has introduced Open Service Navigation Message Authentication (OS NMA), which allows users to verify the authenticity of the GNSS signals received from their devices using a known and secure encryption and authentication algorithm.

Intelligent system design is essential
Ultimately, the most effective protection against GNSS jamming and spoofing is an intelligent system design. This includes, in particular, the use of existing redundancies to detect faults. In smart cars, this could mean that the GNSS-based measurements are compared with those of the vehicle's Dead Reckoning system. If contradictions arise, it would be absolutely clear that something is wrong.

As in IT security, an arms race between the solution providers and those who want to use them for their own agenda is under way. Innovative hardware, a strong commitment to secure positioning solutions and intelligent system design are three key factors in ensuring that GNSS technology continues to serve its legitimate users. 

Guest blog written by Franco de Lorenzo, Product Strategy for Standard Precision GNSS, u-blox Espoo.

Courtesy of u-blox.