Researchers have implemented many security architectures against security vulnerabilities in WSNs. but failed to provide any effective solutions, securing small, tiny and sophisticated nodes till the time. The main obstacles for applying any traditional security solutions are constraints within the architecture of WSN’s. However, developments in last few years, implementation of less power micro-controllers based wireless sensors have been raised very fast as solution of real-world problems. A variety of attacks have been observed to attack these low powered, unattended nodes. Since nodes have limited power battery with a limited life, nodes are not able to perform traditional available security mechanisms or algorithms for prevention. Sybil attack is one of the harmful threat to wireless sensor networks, comprising a malicious node illegally forging an unbounded number of identities. Sybil attack is inspired by polymorphic behavior; having multiple identities simultaneously by a node. In such case, malicious node claims multiple identities or have fake Ids. It is typical but important to detect such guilty nodes from the infrastructure.. This paper aims to the introduction of wireless sensor network architecture, attacks, and attack detection methods. The significance of Sybil attack is also described in detail.
