MAC-TCP cross-layer attack and its defense in cognitive radio networks

Existing research on attacks and security issues in Cognitive Radio networks focus on individual network layers. In this paper, we identify a cross-layer attack, which we call the MAC-TCP Cross-layer attack. This attack is launched from the MAC layer as the point of attack but the final target is to degrade TCP layer end to end throughput of flows by exploiting the TCP congestion control mechanism in cognitive radio. The chances of the attacker being detected are low owing to the fact that the target layer is different from the layer where the attack is launched. An adversary launches an attack on the MAC layer causing large variations in Round Trip Time (RTT) resulting in a large drop in throughput of TCP flows (drop of around 40% from our simulation results) but has little effect on the MAC-layer throughput and hence is very difficult to detect. A defense for this attack is proposed using a deterministic key pre-distribution algorithm where the keys are pre-distributed to nodes. Simulation results show that the throughput is restored to its original levels using key pre-distribution.