Abstract
This paper explores a novel type of attack in wireless sensor networks-Stealth Jamming (SJAM), in which malicious nodes periodically generate bogus traffic in order to trigger false route breakages. More precisely, they target a relatively unexplored weakness inherent in the route maintenance mechanism of ad hoc protocols used by trust-aware routing schemes. Missing a certain number of transmission attempts at the data link layer is typically considered as the link, and consequently route breakage. In this attack, malicious nodes silently listen to the wireless channel, and if the busy airtime (indicative of wireless congestion) exceeds a certain threshold, it starts injecting gratuitous fake broadcast messages for a brief duration, thereby leading to excessive collisions for a transient period and leading to failed transmissions and route breakages, significantly degrading network performance. SJAM is difficult to detect, because the malicious nodes are active only if congestion exceeds a threshold and then only periodically. It is difficult to discern these attacks from genuine route breakages, which are also quite common. In this paper, we explore this type of attack and propose an intelligent cross-layered scheme for mitigating these attacks, thereby improving route stability, throughput, and delay performance. We discuss how enhanced route maintenance in existing trust-aware routing solutions ensures wide applicability of the solution. Simulation results demonstrate the improved network performance when compared with the state-of-the-art solutions.