Mitigating DoS Attacks on CAN: A Priority-Raise Approach and Its Timing Analysis

With an increasing level of interconnection, it has become easier for attackers to target in-vehicle buses in industrial and road vehicles alike. One of the most common attacks is Denial-of-Service (DoS), where the bus is flooded with messages disrupting critical functions and, thereby, jeopardizing the safety of operators and/or passengers. In this paper, we are concerned with DoS attacks on Controller Area Network (CAN) – one of the most popular buses – and propose a priority-raise approach (PRA) to mitigate their impact. Basically, we limit the priority of messages arriving through a gateway from outside the vehicle. If a DoS attack is started, this only affects the messages with lower priority than that used by the attacker. Affected messages can then switch to a higher priority reserved for them, i.e., they can raise their priority, to escape the attack. We investigate a centralized as well as a decentralized priority switching and analyze timing for a varying DoS severity.