1604 | International Journal of Current Engineering and Technology, Vol.4, No.3 (June 2014) Research Article International Journal of Current Engineering and Technology E-ISSN 2277 – 4106, P-ISSN 2347 - 5161 ©2014 INPRESSCO ® , All Rights Reserved Available at http://inpressco.com/category/ijcet Recovering from In-Band Wormhole Based Denial of Service in Wireless Sensor Networks Najma Farooq Ȧ* , Irwa Zahoor Ȧ and Sandip Mandal Ȧ Ȧ Department Of Computer Science And Technology ,Dehradun Institute Of Technology, Mussourie Diversion Road, Makkwala Dehradun, India Accepted 16 May 2014, Available online 01 June 2014, Vol.4, No.3 (June 2014) Abstract Wireless Sensor Networks (WSN) are composed of a large ,yet limited number of sensing devices called sensors, communicating over a wireless media. Wireless sensor networks find prospective applications in fields like environmental monitoring, healthcare, battlefield surveillance, and homeland security. A much broader spectrum of future applications is likely to follow. Deployment of WSN in hostile environments, unattended operation, openness of communication and resource constraints e.g. limited memory, energy and computational capabilities exposes WSN to a number of security attacks. The resource constrained nature of WSN makes conventional security mechanisms incongruous to apply. In this paper, an In-Band wormhole attack on a wireless sensor network is studied, in which an adversary creates a link between two regions of the network by using colluding network nodes. The impact of an In-Band wormhole attack on data transmission and energy consumption in the network is studied and a reactive recovery mechanism to detect and mitigate the Denial Of Service effect caused due to it is presented. Keywords: Wireless Sensor Networks, Wormhole, Denial of Service, Routing Attacks, In-Band Wormhole. 1. Introduction 1 Typically Wireless Sensor Networks are formed of large number of multifunctional resource constrained devices with sensing, data processing and data forwarding capabilities. When compared to other wireless networks, for example, cellular systems and Mobile Adhoc networks, sensor networks are matchlessly characterized by certain features like Dense Node Deployment, application Specific nature, unattended operation, Many - to - One Traffic Pattern, data redundancy etc and are resource constrained with low energy, limited memory and computational capabilities. Due to such type of network characteristics, security objectives are hard and challenging to achieve in wireless sensor networks. Such network characteristics make wireless sensor networks susceptible to various types of security attacks which exploit the fundamental security requirements i.e. confidentiality, authenticity and availability. This paper focuses on denial of service caused due to an In-Band wormhole attack in Wireless Sensor Networks. Wormhole attack is one of the most devastating routing attacks in WSN that is hard to detect and defend (Prasannajit B et.al 2010),(Karlof et.al, 2003). In this attack, a compromised node receives packets at one location of network and tunnels them to another location where the packets are replayed. This attack considerably tribulates a number of network protocols in terms of energy efficiency, routing, localization, service availability *Corresponsing author: Najma Farooq etc. The basic stark feature of wormhole attack lies in the fact that the attackers can easily launch an effective attack without understanding the protocols or cryptographic mechanisms used in the network. Based upon the technique which is used to launch the attack, Wormhole attacks can be classified (Khalil et.al 2007) as shown in the figure 1 Fig 1 shows the classification of wormhole attack based upon the technique used to launch the attack. 1.1 Wormhole using Packet Encapsulation In encapsulation-based wormhole attack, each packet is routed via the legitimate path only, when received by the wormhole end data packets are encapsulated and forwarded via wormhole link ,The packet is brought into original form by the second wormhole end point 1.2 Wormhole using Out-of-Band Channel In this attack the wormhole attack is propelled by having a high-quality, single-hop, out-of-band link between the malicious nodes. This type of attack needs specialized hardware capability. When an adversary creates a