Synchronization of Critical Infrastructures Dependent Upon GNSS: Current Vulnerabilities and Protection Provided by New Signals

Many infrastructures that shape our lifestyle depend on the GPS. Even though not used for positioning, these infrastructures need GPS to derive a precise time synchronization necessary for their operations. Examples are power distribution grids, gateways for financial transactions, and telecommunication networks. However, GPS receivers, and more in general global navigation satellite system (GNSS) receivers, are vulnerable to interference. This makes GNSS-dependent infrastructures prone to time synchronization errors. This paper addresses the vulnerability of GNSS receivers to the intentional injection of counterfeit signals, an operation known as “spoofing.” The analysis is backed by a campaign of tests conducted on three receivers suitable for applications that use GNSS-based synchronization. A battery of spoofing attacks, targeting the control of the output time reference of these receivers, is purposely simulated with lab instrumentation. The effects of such attacks on the receivers' measurements are observed and quantified; they prove that the vulnerability of GNSS receivers to malevolent radio attacks is a quantifiable reality, but such attacks “leave traces” that could trigger their detection. The purpose of this paper is to increase awareness, though not alarm, about the risk represented by time spoofing on application domains used to look at GNSS as a commodity. This paper shows that reducing this risk is possible at both receiver and system level.