A survey of security issues in wireless sensor networks <s> ATTACKS IN SENSOR NETWORKS <s> We consider routing security in wireless sensor networks. Many sensor network routing protocols have been proposed, but none of them have been designed with security as a goal. We propose security goals for routing in sensor networks, show how attacks against ad-hoc and peer-to-peer networks can be adapted into powerful attacks against sensor networks, introduce two classes of novel attacks against sensor networks sinkholes and HELLO floods, and analyze the security of all the major sensor network routing protocols. We describe crippling attacks against all of them and suggest countermeasures and design considerations. This is the first such analysis of secure routing in sensor networks. <s> BIB001 </s> A survey of security issues in wireless sensor networks <s> ATTACKS IN SENSOR NETWORKS <s> Security is important for many sensor network applications. A particularly harmful attack against sensor and ad hoc networks is known as the Sybil attack based on J.R. Douceur (2002), where a node illegitimately claims multiple identities. This paper systematically analyzes the threat posed by the Sybil attack to wireless sensor networks. We demonstrate that the attack can be exceedingly detrimental to many important functions of the sensor network such as routing, resource allocation, misbehavior detection, etc. We establish a classification of different types of the Sybil attack, which enables us to better understand the threats posed by each type, and better design countermeasures against each type. We then propose several novel techniques to defend against the Sybil attack, and analyze their effectiveness quantitatively. <s> BIB002
WSNs are vulnerable to various types of attacks. According to the security requirements in WSNs, these attacks can be categorized as  : • Attacks on secrecy and authentication: standard cryptographic techniques can protect the secrecy and authenticity of communication channels from outsider attacks such as eavesdropping, packet replay attacks, and modification or spoofing of packets. • Attacks on network availability: attacks on availability are often referred to as denial-of-service (DoS) attacks. DoS attacks may target any layer of a sensor network. • Stealthy attacks against service integrity: in a stealthy attack, the goal of the attacker is to make the network accept a false data value. For example, an attacker compromises a sensor node and injects a false data value through that sensor node. In these attacks, keeping the sensor network available for its intended use is essential. DoS attacks against WSNs may permit real-world damage to the health and safety of people [5] . In this section, we focus only on DoS attacks and their countermeasures in sensor networks. We discuss attacks on secrecy and authentication in the section "Secure Routing Protocols," and discuss stealthy attacks and countermeasures in the section "Intrusion Detection" below. The DoS attack usually refers to an adversary's attempt to disrupt, subvert, or destroy a network. However, a DoS attack can be any event that diminishes or eliminates a network's capacity to perform its expected function [5] . Sensor networks are usually divided into layers, and this layered architecture makes WSNs vulnerable to DoS attacks, as DoS attacks may occur in any layer of a sensor network. Previous discussions on DoS attacks in WSNs can be found in  5, BIB001 BIB002 . The remainder of this section summarizes the possible DoS attacks and countermeasures in each layer of a sensor network.