Abstract
A well-known dangerous attacks against Wireless Sensor Networks(WSNs) is Sybil attack in which a malicious node propagates mul-tiple fake identities. This attack affects routing protocols and many usual operations ofWSNs including voting and data aggregation. In this paper, a novel algorithm has been proposed for detecting this attack in static WSNs. There are several mobile observer nodes in the proposed algorithm, which walk in the network’s environment continuously. They first detect areas suspicious to Sybil attack and then record information about these areas in their memories. Using stored information, they will be able to detect Sybil nodes. The proposed algorithm is implemented using JSIM simulator and its efficiency has been compared to other existing algorithms in terms of true detection and false detection rates. The results show that the proposed algorithm can detect 99% of Sybil nodes on average, while the false detection rate is about 5%