Prevention and Detection of Intrusions in Wireless Sensor Networks

Wireless Sensor Networks (WSNs) continue to grow as one of the most exciting and challenging research areas of engineering. They are characterized by severely constrained computational and energy resources and also restricted by the ad-hoc network operational environment. They pose unique challenges, due to limited power supplies, low transmission bandwidth, small memory sizes and limited energy. Therefore, security techniques used in traditional networks cannot be directly adopted. So, new ideas and approaches are needed, in order to increase the overall security of the network. Security applications in such resource constrained WSNs with minimum overhead provides significant challenges, and is the main focus of this dissertation. There is no one size fits all solution in defending WSNs against intrusions and attacks. Therefore, intrusions and attacks against WSNs should be carefully examined to reveal specific vulnerabilities associated with them, before beginning the design of any kind of intrusion prevention and detection systems. By following this rationale, the dissertation starts with providing information regarding the WSNs, types of attacks towards WSNs, and the methods on how to prevent and detect them. Then, in order to secure WSNs, a security provisioning plan is provided. In general, the following processes may be involved in securing WSNs: Intrusion Prevention, Intrusion Detection, and Intrusion Mitigation. This dissertation presents solutions (algorithms and schemes) to the first two lines of defenses of the security provisioning plan, namely, Intrusion Prevention and Intrusion Detection. As a first line of defense in securing WSNs, this dissertation presents our proposed algorithm ( Two-Level User Authentication scheme) as an Intrusion Prevention System (IPS) for WSNs. The algorithm uses two-level authentication between a sensor node and a user. It is designed for heterogeneous WSNs, meaning that the network consists of two components: regular nodes and more powerful cluster heads. The proposed scheme is evaluated both analytically and also in a simulation environment, by comparing it to the current state-of-the-art schemes in the literature. A comprehensive and systematic survey of the state-of-the-art in Intrusion Detection Systems (IDSs) that are proposed for Mobile Ad-Hoc Networks (MANETs) and WSNs is presented. Firstly, detailed information about IDSs is provided. This is followed by the analysis and comparison of each scheme along with their advantages and disadvantages from the perspective of security. Finally, guidelines on IDSs that are potentially applicable to WSNs are provided. Overall, this work would be very helpful to the researchers in developing their own IDSs for their WSNs. Clustering (of the nodes) is very important for WSNs not only in data aggregation, but also in increasing the overall performance of the network, especially in terms of total life-time. Besides, with the help of clustering, complex intrusion prevention and detection algorithms can be implemented. Therefore, background on the clustering algorithms is provided and then a clustering algorithm for WSNs is proposed, that is both power and connectivity aware. The proposed algorithm provides higher energy efficiency and increases the life-time of the network. In evaluating the proposed clustering algorithm (in a simulation environment by comparing its\u27 performance to the previously proposed algorithm, namely Kachirski et al.\u27s algorithm), it is demonstrated that the proposed algorithm improves energy efficiency in WSNs. Finally, an IDS framework based on multi-level clustering for hierarchical WSNs is proposed. It is based upon (the nodes use our proposed clustering algorithm while forming their clusters) the clustering algorithm that is proposed in this dissertation. The framework provides two types of intrusion detection approaches, namely Downwards-IDS (D-IDS) to detect the abnormal behavior (intrusion) of the subordinate (member) nodes and Upwards-IDS (U-IDS) to detect the abnormal behavior of the cluster heads. By using analytical calculations, the optimum parameters for the D-IDS (number of maximum hops) and U-IDS (monitoring group size) of the framework are evaluated and presented. Overall, this dissertation research contributes to the first two lines of defenses towards the security of WSNs, namely, IPS and IDS. Furthermore, the final contribution of this dissertation is towards the topology formation of the WSNs (especially for the hierarchical WSNs), namely, clustering; which would be very useful in implementation of the IPS and IDS systems that are presented in this dissertation