Tracking Vehicles in Cooperative Intelligent Transportation Systems: Attacks, Defense Solutions, and Future Directions

The Cooperative Intelligent Transportation System (C-ITS) is vital in enhancing road safety, improving traffic efficiency, and increasing user comfort for pedestrians and drivers. However, as vehicle communications evolve, security threats that aim to undermine critical security services, such as data confidentiality, integrity, and privacy, have become crucial issues that must be addressed. Privacy, the freedom from interference or intrusion, is also considered one of the most significant challenges in computer networks and connected vehicles. Privacy in C-ITS can be protected by preventing both the collection of personal information and the tracking of vehicles by malicious users. Tracking is often achieved through the periodic transmission of Cooperative Awareness Messages (CAMs), which contain spatio-temporal information such as position and speed. We investigate key tracking-related critical issues in intelligent connected vehicles. We highlight current security challenges and attacks that lead to the unauthorized tracking of connected cars. We discuss various defense solutions proposed in the literature to address these challenges. We classify these solutions into two groups: general (addressing eavesdropping, Sybil, etc.) and pseudonym change (addressing correlation, swap, silent periods, and mix-zones). Finally, we explore robust future strategies to prevent tracking attacks on the C-ITS.