Combating persistent adversaries in wireless sensor networks using directional antennas

Security is an important property in applications offering services in mission-critical areas, such as in healthcare, military, transportation, etc. Wireless sensor networks (WSN) support the mission of these applications by monitoring the environment and reporting observations to appropriate authorities that are responsible for decision-making. Often, their operation can be at risk by adversaries that launch attacks against the WSN with the aim of compromising the reliability and availability of the network and the respective application. The outcome of an attack highly depends on the experience of the adversary and his capabilities in terms of programming skills, security knowledge and resources. From the network perspective, the challenge is to reliably recover to a normal operation as soon as the adversary is been detected and allow for packet delivery to destination. The challenge is even greater in the presence of adversaries that adapt their intrusion strategy to break the deployed recovery countermeasures and continue affecting the network. Proposed recovery countermeasures typically assume the use of omni-directional antennas, which cannot take advantage of antenna directivity in order to manipulate communication paths between WSN nodes for the purpose of (physically) bypassing an adversary. This paper presents an intrusion recovery protocol in WSNs that uses directional antennas to create controlled communication paths, thus routing, and enhancing the reliability, self-healingness and resilience of the network. The proposed protocol is implemented within the AODV context and evaluated using ns-2. We demonstrate the effectiveness of the proposed protocol to deliver packets to the destination in the presence of multiple persistent adversaries that deploy different types of simple to extended attacks.