Covert channels in ad-hoc wireless networks

A covert channel is a concealed communication path embedded in an overt one. Existence of covert channels violates both secrecy and integrity properties of trusted systems. While past covert analysis has been mainly focused on wired networks, the wireless communication environment involves fundamentally different properties that make it vulnerable to covert attacks. In particular, nodes in ad-hoc wireless networks have to cooperate with each other in order to accomplish many networking functions as routing and channel access. We observe that covert information can be conveyed during the cooperation procedure. This paper investigates ad-hoc wireless networks' susceptibility to covert channels that can be formed through manipulating the network protocols. It is very difficult to eliminate or even detect these covert channels. Simulation results show that performance of these covert channels depends on various network characteristics. Countermeasures against the covert channel are needed and also should adapt to the network changes to take full effect. (C) 2009 Published by Elsevier B.V.