Analysing indirect Sybil attacks in randomly deployed Wireless Sensor Networks

Wireless Sensor Networks (WSNs) have been established as a valuable tool in a wide variety of applications, systems and paradigms. Many application, such as surveillance of a military region, entail unattended operation, where sensor nodes are randomly deployed in an area, known as sensor area. Such a sensor network may be vulnerable to several harmful threats such as wormhole, blackhole, selective forwarding, hello flood, and Sybil attack. One of the most complicated threat is the Sybil attack, where one or more malicious nodes illegitimately declare multiple identities. Additionally, the attack could be even more arduous, if the malicious node(s) declare that the Sybil nodes are directly connected to them. The so-called indirect Sybil attack is the main focus of this study. A performance analysis is devised, where the expected potential number of indirect Sybil nodes in randomly deployed WSNs is computed. Moreover, the probability of an (indirect) Sybil-free sensor network is calculated subject to the number of sensor nodes and the sensor area intensity. The analysis is thoroughly validated by simulation results.