A Review on Detection and Counter Measures of Wormhole Attack in Wireless Sensor Network Rabia Arshad, Saba Zia Abstract- Sensor nodes are organized to form wireless sensor network to be deployed in hostile environments. Sensor nodes communicate each other routing protocols. Information from source node to destination node is sent via intermediate nodes. Security is a major issue in WSN in present days as WSN is vulnerable to attacks that can cause damage to the functionality of the system. In this survey paper an attempt has been made to analyze security threats to WSN at network layer. Network layers is affected by many attacks e.g. Black Hole Attack, Grey Hole Attack, Wormhole Attack, out of which Wormhole attack is the most devastating where attacker agents make a link between two points with low latency. This paper focuses on some researches in detecting and preventing the wormhole attack in network layer. Keywords- Mobile Adhoc Network, Security, Wireless Sensor Network, Wormhole Attacks I. INTRODUCTION WSN [1-5] is composed of numerous sensor nodes that are capable of monitoring environmental conditions. Sensor nodes are responsible for transmitting the information in the network. Transmitting data in the WSN is a critical task because sensor nodes are restricted devices. Due to this reason, sensor network is susceptible to many attacks. WSNs have some special features that distinguish them from other networks. These characteristics are given as follows [18]:  Limited resources  Minimum battery life span  Self-configuration  Random changes in topology of network  Centralized approach of network control Security is one of the important challenges in designing the WSN. Data is vulnerable to attacks of many kinds therefore security measurements should be taken while designing the WSN. Many security attacks can affect the performance of WSN e.g. Black hole [19], Grey hole [20], Wormhole attack. Wormhole attack is the most dangerous attack to WSN. From this point of view, this paper briefly describes the techniques for detection and prevention of wormhole attack. Rest of the paper is described as follows:  Section 2 describes about the challenges of WSN.  In section 3 various attacks on WSN are summarized.  Section 4 covers the background of Wormhole attack  Section 5 describes the different types of Wormhole attack  In section 6, different modes of wormhole attack are discussed  Section 7 listed some counter measures to wormhole attack International Journal of Computer Science and Information Security (IJCSIS), Vol. 15, No. 12, December 2017 155 https://sites.google.com/site/ijcsis/ ISSN 1947-5500