Avoiding Virtual Link Attacks in Wireless Ad Hoc Networks

A mobile ad hoc network is made of a collection of nodes connected through a wireless medium and form a wireless multihop network with possible changing topologies. The widely accepted existing muting protocols designed to accommodate the needs of such self-organized networks do not address possible threats or attacks aiming at the disruption of the protocol itself. The widely assumed trusted environment is not really the environment that can be realistically expected in reality. In this paper, we describe a new attack against routing protocols which we call virtual link attack, where a misbehaving node tries to relay any Hello message originated from its neighbors aiming to create fake symmetric links in the network. We show that this attack can severely compromise any muting protocol and may lead to large data packets loss. We specifically analyze this attack under the Optimized Link State Routing (OLSR) protocol in detail and devise a Symmetric Neighbor Verification Protocol (SNVP) to alleviate its impact and severity.