Detecting and Evading Wormholes in Mobile Ad-hoc Wireless Networks

Mobile ad-hoc wireless networks are established in improvised environments through the mutual cooperation of its participating nodes. These nodes often operate in a physically insecure environment and, as a result, are vulnerable to capture and compromise. In addition, the nature of the wireless communication medium restricts enforcement of rigourous node memberships and so a number of malicious nodes may also participate in the network. These nodes, in order to snoop or sabotage, can undertake a variety of attacks against the network. Among these, wormhole attacks have unusual significance primarily due to their modus operandi and peculiar attack pattern. In such attacks, two or more malicious colluding nodes create a higher level virtual tunnel in the network, which is employed to transport packets between the tunnel endpoints. These tunnels emulate shorter links in the network and so act as bait to unsuspecting network nodes which, by default, seek shorter routes. The benefit gained by the malicious nodes is that they are able to conduct a variety of attacks against the tunnelled traffic. In this paper, we present a novel trust-based scheme for identifying and isolating nodes that create a wormhole in the network, without engaging any cryptographic means. With the help of extensive simulations, we demonstrate that our scheme functions effectively in the presence of malicious colluding nodes and does not impose any unnecessary conditions upon the network establishment and operation phase.