The availability of cheap GNSS spoofers can prevent safe navigation and
tracking of road users. It can lead to loss of assets, inaccurate fare
estimation, enforcing the wrong speed limit, miscalculated toll tax, passengers
reaching an incorrect location, etc. The techniques designed to prevent and
detect spoofing by using cryptographic solutions or receivers capable of
differentiating legitimate and attack signals are insufficient in detecting
GNSS spoofing of road users. Recent studies, testbeds, and 3GPP standards are
exploring the possibility of hybrid positioning, where GNSS data will be
combined with the 5G-NR positioning to increase the security and accuracy of
positioning. We design the Location Estimation and Recovery(LER) systems to
estimate the correct absolute position using the combination of GNSS and 5G
positioning with other road users, where a subset of road users can be
malicious and collude to prevent spoofing detection. Our Location Verification
Protocol extends the understanding of Message Time of Arrival Codes (MTAC) to
prevent attacks against malicious provers. The novel Recovery and Meta Protocol
uses road users' dynamic and unpredictable nature to detect GNSS spoofing. This
protocol provides fast detection of GNSS spoofing with a very low rate of false
positives and can be customized to a large family of settings. Even in a
(highly unrealistic) worst-case scenario where each user is malicious with a
probability of as large as 0.3, our protocol detects GNSS spoofing with high
probability after communication and ranging with at most 20 road users, with a
false positive rate close to 0. SUMO simulations for road traffic show that we
can detect GNSS spoofing in 2.6 minutes since its start under moderate traffic
conditions