Attacks and Countermeasures in Sensor Networks: A Survey
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paper_title: Eavesdropping games: a graph-theoretic approach to privacy in distributed systems

paper_content:

We initiate a graph-theoretic study of privacy in distributed environments with mobile eavesdroppers ("bugs"). For two privacy tasks—distributed database maintenance and message transmission—a computationally unbounded adversary “plays an eavesdrpping game,” coordinating the moment of the bugs among the sites to learn the current memory contents. Many different adversaries are considered, motivated by differences in eavesdropping technologies. We characterize the feasibility of the two privacy tasks combinatorially, construct protocols for the feasible cases, and analyze their computational complexity.
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paper_title: Formal Eavesdropping and Its Computational Interpretation

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We compare two views of symmetric cryptographic primitives in the context of the systems that use them. We express those systems in a simple programming language; each of the views yields a semantics for the language. One of the semantics treats cryptographic operations formally (that is, symbolically). The other semantics is more detailed and computational; it treats cryptographic operations as functions on bitstrings. Each semantics leads to a definition of equivalence of systems with respect to eavesdroppers. We establish the soundness of the formal definition with respect to the computational one. This result provides a precise computational justification for formal reasoning about security against eavesdroppers.
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paper_title: Directional virtual carrier sensing for directional antennas in mobile ad hoc networks

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This paper presents a new carrier sensing mechanism called DVCS (Directional Virtual Carrier Sensing) for wireless communication using directional antennas. DVCS does not require specific antenna configurations or external devices. Instead it only needs information on AOA (Angle of Arrival) and antenna gain for each signal from the underlying physical device, both of which are commonly used for the adaptation of antenna pattern. DVCS also supports interoperability of directional and omni-directional antennas. In this study, the performance of DVCS for mobile ad hoc networks is evaluated using simulation with a realistic directional antenna model and the full IP protocol stack. The experimental results showed that compared with omni-directional communication, DVCS improved network capacity by a factor of 3 to 4 for a 100 node ad hoc network.
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paper_title: Using Directional Antennas to Prevent Wormhole Attacks

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Wormhole attacks enable an attacker with limited resources and no cryptographic material to wreak havoc on wireless networks. To date, no general defenses against wormhole attacks have been proposed. This paper presents an analysis of wormhole attacks and proposes a countermeasure using directional antennas. We present a cooperative protocol whereby nodes share directional information to prevent wormhole endpoints from masquerading as false neighbors. Our defense greatly diminishes the threat of wormhole attacks and requires no location information or clock synchronization.
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paper_title: On the performance of ad hoc networks with beamforming antennas

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Beamforming antennas have the potential to provide a fundamental breakthrough in ad hoc network capacity. We present a broad-based examination of this potential, focusing on exploiting the longer ranges as well as the reduced interference that beamforming antennas can provide. We consider a number of enhancements to a convectional ad hoc network system, and evaluation the impact of each enhancement using simulation. Such enhancements include "aggressive" and "conservative" channel access models for beamforming antennas, link power control, and directional neighbor discovery. Our simulations are based on detailed modeling on detailed modeling of steered as well as swiched beams using antenna patterns of varying gains, and a realistic radio and propagation model. For the scenarios studied, our results show that beamforming can yield a 28% to 118% (depending upon the density) improvement in throughput, and up to a factor-of-28 reduction in delay. Our study also tells us which mechanisms are likely to be more effective and under what conditions, which in turn identifies areas where future research is neede
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paper_title: Using Directional Antennas for Medium Access Control in Ad Hoc Networks

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A composition for use in the treatment for developing seedless fleshy berry of grapes. By treating the flower bunches of a grape tree with a composition containing gibberellin and cyclic 3',5'-adenylic acid in the form of an aqueous solution, it became possible to make seedless fleshy berry from grape trees belonging to varieties other than Delaware, namely belonging to Campbell-Arley, Berry A, Niagara, Kyoho, etc., from which seedless fleshy berry cannot be made by the conventional treatment with gibberellin.
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paper_title: On the capacity improvement of ad hoc wireless networks using directional antennas

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The capacity of ad hoc wireless networks is constrained by the interference between concurrent transmissions from neighboring nodes. Gupta and Kumar have shown that the capacity of an ad hoc network does not scale well with the increasing number of nodes in the system when using omnidirectional antennas [6]. We investigate the capacity of ad hoc wireless networks using directional antennas. In this work, we consider arbitrary networks and random networks where nodes are assumed to be static.In arbitrary networks, due to the reduction of the interference area, the capacity gain is proven to be √2π/α when using directional transmission and omni reception. Because of the reduced probability of two neighbors pointing to each other, the capacity gain is √2π/β when omni transmission and directional reception are used. Although these two expressions look similar, the proof technique is different. By taking advantage of the above two approaches, the capacity gain is 2π/√αβ when both transmission and reception are directional.For random networks, interfering neighbors are reduced due to the decrease of interference area when directional antennas are used for transmission and/or reception. The throughput improvement factor is 2π/α, 2π/β and 4π2/αβ for directional transmission/omni reception, omni transmission/direc-tional reception, and directional transmission/directional reception, respectively.We have also analyzed hybrid beamform patterns that are a mix of omnidirectional/directional and a better model of real directional antennas.
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paper_title: PIKE: peer intermediaries for key establishment in sensor networks

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The establishment of shared cryptographic keys between communicating neighbor nodes in sensor networks is a challenging problem due to the unsuitability of asymmetric key cryptography for these resource-constrained platforms. A range of symmetric-key distribution protocols exist, but these protocols do not scale effectively to large sensor networks. For a given level of security, each protocol incurs a linearly increasing overhead in either communication cost per node or memory per node. We describe peer intermediaries for key establishment (PIKE), a class of key-establishment protocols that involves using one or more sensor nodes as a trusted intermediary to facilitate key establishment. We show that, unlike existing key-establishment protocols, both the communication and memory overheads of PIKE protocols scale sub-linearly (O(/spl radic/n)) with the number of nodes in the network yet achieving higher security against node compromise than other protocols.
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paper_title: A pairwise key predistribution scheme for wireless sensor networks

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To achieve security in wireless sensor networks, it is important to be able to encrypt and authenticate messages sent between sensor nodes. Before doing so, keys for performing encryption and authentication must be agreed upon by the communicating parties. Due to resource constraints, however, achieving key agreement in wireless sensor networks is nontrivial. Many key agreement schemes used in general networks, such as Diffie-Hellman and other public-key based schemes, are not suitable for wireless sensor networks due to the limited computational abilities of the sensor nodes. Predistribution of secret keys for all pairs of nodes is not viable due to the large amount of memory this requires when the network size is large.In this paper, we provide a framework in which to study the security of key predistribution schemes, propose a new key predistribution scheme which substantially improves the resilience of the network compared to previous schemes, and give an in-depth analysis of our scheme in terms of network resilience and associated overhead. Our scheme exhibits a nice threshold property: when the number of compromised nodes is less than the threshold, the probability that communications between any additional nodes are compromised is close to zero. This desirable property lowers the initial payoff of smaller-scale network breaches to an adversary, and makes it necessary for the adversary to attack a large fraction of the network before it can achieve any significant gain.
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paper_title: A key-management scheme for distributed sensor networks

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Distributed Sensor Networks (DSNs) are ad-hoc mobile networks that include sensor nodes with limited computation and communication capabilities. DSNs are dynamic in the sense that they allow addition and deletion of sensor nodes after deployment to grow the network or replace failing and unreliable nodes. DSNs may be deployed in hostile areas where communication is monitored and nodes are subject to capture and surreptitious use by an adversary. Hence DSNs require cryptographic protection of communications, sensor-capture detection, key revocation and sensor disabling. In this paper, we present a key-management scheme designed to satisfy both operational and security requirements of DSNs. The scheme includes selective distribution and revocation of keys to sensor nodes as well as node re-keying without substantial computation and communication capabilities. It relies on probabilistic key sharing among the nodes of a random graph and uses simple protocols for shared-key discovery and path-key establishment, and for key revocation, re-keying, and incremental addition of nodes. The security and network connectivity characteristics supported by the key-management scheme are discussed and simulation experiments presented.
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paper_title: Establishing pairwise keys in distributed sensor networks

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Pairwise key establishment is a fundamental security service in sensor networks; it enables sensor nodes to communicate securely with each other using cryptographic techniques. However, due to the resource constraints on sensors, it is infeasible to use traditional key management techniques such as public key cryptography and key distribution center (KDC). To facilitate the study of novel pairwise key predistribution techniques, this paper presents a general framework for establishing pairwise keys between sensors on the basis of a polynomial-based key predistribution protocol [2]. This paper then presents two efficient instantiations of the general framework: a random subset assignment key predistribution scheme and a grid-based key predistribution scheme. The analysis in this paper indicates that these two schemes have a number of nice properties, including high probability (or guarantee) to establish pairwise keys, tolerance of node captures, and low communication overhead. Finally, this paper presents a technique to reduce the computation at sensors required by these schemes.
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paper_title: Providing robust and ubiquitous security support for mobile ad-hoc networks

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Providing security support for mobile ad-hoc networks is challenging for several reasons: (a) wireless networks are susceptible to attacks ranging from passive eavesdropping to active interfering, occasional break-ins by adversaries may be inevitable in a large time window; (b) mobile users demand "anywhere, anytime" services; (c) a scalable solution is needed for a large-scale mobile network. In this paper, we describe a solution that supports ubiquitous security services for mobile hosts, scales to network size, and is robust against break-ins. In our design, we distribute the certification authority functions through a threshold secret sharing mechanism, in which each entity holds a secret share and multiple entities in a local neighborhood jointly provide complete services. We employ localized certification schemes to enable ubiquitous services. We also update the secret shares to further enhance robustness against break-ins. Both simulations and implementation confirm the effectiveness of our design.
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paper_title: Random key predistribution schemes for sensor networks

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Key establishment in sensor networks is a challenging problem because asymmetric key cryptosystems are unsuitable for use in resource constrained sensor nodes, and also because the nodes could be physically compromised by an adversary. We present three new mechanisms for key establishment using the framework of pre-distributing a random set of keys to each node. First, in the q-composite keys scheme, we trade off the unlikeliness of a large-scale network attack in order to significantly strengthen random key predistribution's strength against smaller-scale attacks. Second, in the multipath-reinforcement scheme, we show how to strengthen the security between any two nodes by leveraging the security of other links. Finally, we present the random-pairwise keys scheme, which perfectly preserves the secrecy of the rest of the network when any node is captured, and also enables node-to-node authentication and quorum-based revocation.
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paper_title: Non-Public Key Distribution

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Assume that it should be possible to protect messages transmitted in a N-user network by encryption. The encryption can either be performed by a public-key crypto system or by a conventional cipher. In the first case there is no need for key distribution. In the second case we have two choices, either to distribute keys from a key distribution center or use a public key distribution algorithm.
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paper_title: Detection and prevention of MAC layer misbehavior in ad hoc networks

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Selfish behavior at the MAC layer can have devastating side effects on the performance of wireless networks, similar to the effects of DoS attacks. In this paper we focus on the prevention and detection of the manipulation of the backoff mechanism by selfish nodes in 802.11. We first propose an algorithm to ensure honest backoffs when at least one, either the receiver or the sender is honest. Then we discuss detection algorithms to deal with the problem of colluding selfish nodes. Although we have focused on the MAC layer of 802.11, our approach is general and can serve as a guideline for the design of any probabilistic distributed MAC protocol.
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paper_title: Denial of Service in Sensor Networks

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Sensor networks hold the promise of facilitating large-scale, real-time data processing in complex environments, helping to protect and monitor military, environmental, safety-critical, or domestic infrastructures and resources, Denial-of-service attacks against such networks, however, may permit real world damage to public health and safety. Without proper security mechanisms, networks will be confined to limited, controlled environments, negating much of the promise they hold. The limited ability of individual sensor nodes to thwart failure or attack makes ensuring network availability more difficult. To identify denial-of-service vulnerabilities, the authors analyzed two effective sensor network protocols that did not initially consider security. These examples demonstrate that consideration of security at design time is the best way to ensure successful network deployment.
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paper_title: Denial of service attacks at the MAC layer in wireless ad hoc networks

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We analyze attacks that deny channel access by causing pockets of congestion in mobile ad hoc networks. Such attacks would essentially prevent one or more nodes from accessing or providing specific services. In particular, we focus on the properties of the popular medium access control (MAC) protocol, the IEEE 802.11x MAC protocol, which enable such attacks. We consider various traffic patterns that an intelligent attacker might generate in order to cause denial of service. We show that conventional methods used in wire-line networks are unable to help in prevention or detection of such attacks. Our analysis and simulations show that providing MAC layer fairness alleviates the effects of such attacks.
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paper_title: Denial of service resilience in ad hoc networks

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Significant progress has been made towards making ad hoc networks secure and DoS resilient. However, little attention has been focused on quantifying DoS resilience: Do ad hoc networks have sufficiently redundant paths and counter-DoS mechanisms to make DoS attacks largely ineffective? Or are there attack and system factors that can lead to devastating effects? In this paper, we design and study DoS attacks in order to assess the damage that difficult-to-detect attackers can cause. The first attack we study, called the JellyFish attack, is targeted against closed-loop flows such as TCP; although protocol compliant, it has devastating effects. The second is the Black Hole attack, which has effects similar to the JellyFish, but on open-loop flows. We quantify via simulations and analytical modeling the scalability of DoS attacks as a function of key performance parameters such as mobility, system size, node density, and counter-DoS strategy. One perhaps surprising result is that such DoS attacks can increase the capacity of ad hoc networks, as they starve multi-hop flows and only allow one-hop communication, a capacity-maximizing, yet clearly undesirable situation.
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paper_title: The Sybil Attack

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Large-scale peer-to-peer systems face security threats from faulty or hostile remote computing elements. To resist these threats, many such systems employ redundancy. However, if a single faulty entity can present multiple identities, it can control a substantial fraction of the system, thereby undermining this redundancy. One approach to preventing these "Sybil attacks" is to have a trusted agency certify identities. This paper shows that, without a logically centralized authority, Sybil attacks are always possible except under extreme and unrealistic assumptions of resource parity and coordination among entities.
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paper_title: The sybil attack in sensor networks: analysis & defenses

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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.
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paper_title: Intrusion Detection in Wireless Ad Hoc Networks

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Intrusion detection has, over the last few years, assumed paramount importance within the broad realm of network security and it has significant impact on wireless ad hoc networks. These networks do not have an underlying infrastructure and the network topology constantly changes. The inherently vulnerable characteristics of wireless ad hoc networks make them susceptible to attacks, and it may be difficult to control before any prevention works out. Secondly, with so much advancement in hacking, if attackers use sophisticated technology, they will eventually succeed in infiltrating the system. This makes it important to constantly or periodically monitor what is taking place on a system and look for suspicious behavior. Intrusion detection systems (IDS)monitor audit data, look for intrusions to the system, and initiate a proper response. In this paper, we present a method for determining critical path that use the distributed security scheme to find out the malicious node. The nodes with the help of the critical links will find out the malicious node using distributed security scheme and inform all the nodes about malicious node. The simulation results describe the details of the critical path test.
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paper_title: Detection and prevention of MAC layer misbehavior in ad hoc networks

paper_content:

Selfish behavior at the MAC layer can have devastating side effects on the performance of wireless networks, similar to the effects of DoS attacks. In this paper we focus on the prevention and detection of the manipulation of the backoff mechanism by selfish nodes in 802.11. We first propose an algorithm to ensure honest backoffs when at least one, either the receiver or the sender is honest. Then we discuss detection algorithms to deal with the problem of colluding selfish nodes. Although we have focused on the MAC layer of 802.11, our approach is general and can serve as a guideline for the design of any probabilistic distributed MAC protocol.
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paper_title: Mitigating routing misbehavior in mobile ad hoc networks

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This paper describes two techniques that improve throughput in an ad hoc network in the presence of nodes that agree to forward packets but fail to do so. To mitigate this problem, we propose categorizing nodes based upon their dynamically measured behavior. We use a watchdog that identifies misbehaving nodes and a pathrater that helps routing protocols avoid these nodes. Through simulation we evaluate watchdog and pathrater using packet throughput, percentage of overhead (routing) transmissions, and the accuracy of misbehaving node detection. When used together in a network with moderate mobility, the two techniques increase throughput by 17% in the presence of 40% misbehaving nodes, while increasing the percentage of overhead transmissions from the standard routing protocol's 9% to 17%. During extreme mobility, watchdog and pathrater can increase network throughput by 27%, while increasing the overhead transmissions from the standard routing protocol's 12% to 24%.
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paper_title: Intrusion Detection Techniques for Mobile Wireless Networks

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The rapid proliferation of wireless networks and mobile computing applications has changed the landscape of network security. The traditional way of protecting networks with firewalls and encryption software is no longer sufficient and effective. We need to search for new architecture and mechanisms to protect the wireless networks and mobile computing application. In this paper, we examine the vulnerabilities of wireless networks and argue that we must include intrusion detection in the security architecture for mobile computing environment. We have developed such an architecture and evaluated a key mechanism in this architecture, anomaly detection for mobile ad-hoc network, through simulation experiments.
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paper_title: On Cheating in CSMA/CA Ad Hoc Networks

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CSMA/CA protocols rely on the random deferment of packet transmissions. Like most other protocols, CSMA/CA was designed with the assumption that the nodes would play by the rules. This is important, since the nodes themselves control their random deferment. However, with the higher programmability of the network adapters, the temptation to tamper with the software or firmware is likely to grow; in this way, a user could obtain a much larger share of the available bandwidth at the expense of other users. We use a game-theoretic approach to investigate the problem of the selfish behavior of nodes, specifically geared towards the most widely accepted protocol in this class of protocols, IEEE 802.11. We show that a selfish and non-cooperative behavior by a small population of (two or more) cheaters leads to a network collapse. We argue that this provides an incentive for cheaters to cooperate with each other. However, explicit cooperation among nodes is clearly impractical. By applying the model of dynamic games borrowed from game theory, we derive the conditions for the stable and optimal functioning of a population of cheaters. We use this insight to develop a simple, localized and distributed cheating protocol that needs no explicit cooperation between cheaters or \textit{a priori} knowledge about the total number of nodes/cheaters in the system. We show that the scheme successfully guides multiple selfish nodes to a Pareto-optimal Nash equilibrium.
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paper_title: CORE: A Collaborative Reputation Mechanism to enforce node cooperation in Mobile Ad hoc Networks

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Countermeasures for node misbehavior and selfishness are mandatory requirements in MANET. Selfishness that causes lack of node activity cannot be solved by classical security means that aim at verifying the correctness and integrity of an operation. We suggest a generic mechanism based on reputation to enforce cooperation among the nodes of a MANET to prevent selfish behavior. Each network entity keeps track of other entities’ collaboration using a technique called reputation. The reputation is calculated based on various types of information on each entity’s rate of collaboration. Since there is no incentive for a node to maliciously spread negative information about other nodes, simple denial of service attacks using the collaboration technique itself are prevented. The generic mechanism can be smoothly extended to basic network functions with little impact on existing protocols.
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paper_title: Sensors for Detection of Misbehaving Nodes in MANETs

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The fact that security is a critical problem when implementing mobile ad hoc networks (MANETs) is widely acknowledged. One of the different kinds of misbehavior a node may exhibit is selfishness. A selfish node wants to preserve its resources while using the services of others and consuming their resources. One way of preventing selfishness in a MANET is a detection and exclusion mechanism. In this paper, we focus on the detection and present different kinds of sensors that will find selfish nodes. First we present simulations that show the negative effects which selfish nodes cause in MANET. In the related work section we will analyze the detection mechanisms proposed by others. Our new detection mechanisms that we describe in this paper are called activity-based overhearing, iterative probing, and unambiguous probing. Simulation-based analysis of these mechanisms show that they are highly effective and can reliably detect a multitude of selfish behaviors. 1 Selfish nodes in MANETs Mobile ad hoc networks (MANETs) rely on the cooperation of all participating nodes. The more nodes cooperate to transfer traffic, the more powerful a MANET gets. But supporting a MANET is a cost-intensive activity for a mobile node. Detecting routes and forwarding packets consumes local CPU time, memory, network-bandwidth, and last but not least energy. Therefore there is a strong motivation for a node to deny packet forwarding to others while at the same time using their services to deliver own data. In table 1, we analyze different possibilities for a selfish node to save its own resources in a MANET based on the DSR routing protocol [JMHJ03, Pe01]. It uses the attack-tree notation proposed by Bruce Schneier [Sc99] that allows the analysis of different ways how an attacker can achieve his goal. Alternatives to reach a certain goal are denoted by OR, multiple steps that are necessary to reach a goal are denoted by AND. Using the numbers in the table, we can easily describe different attacks. For example, attack 3.1 stands for ”Drop data packets”. Whereas most of the attacks based on manipulations of routing data can be detected by the use of a secure routing protocol like Ariadne [HPJ02], SRP [PH02a, PH02b, PH02c, PHS02, PH03], ARAN [SDL02], or SAODV [Gu02, GA02], there remain two attacks in the attack tree that cannot be detected this easily. When nodes simply drop packets (case 1.1 and 3.1 in the attack tree), all of the secure routing protocols fail as they focus only on Attack tree: Save own resources OR 1. Do not participate in routing OR 1. Do not relay routing data OR 1. Do not relay route requests 2. Do not relay route replies 3. Set hop limit or TTL value in route request/reply to smallest possible value 2. Modify routing data/topology OR 1. Modify route request OR 1. Insert additional hops 2. Modify route reply OR 1. Replace own ID in returned route with detour leading through neighboring nodes 2. Return completely wrong route, provoking RERR and salvaging 3. Insert additional hops 4. Declare own ID in source route as external 2. Stop participation in current route AND 1. Provoke route error OR 1. Create arbitrary RERR messages 2. Do not send ACK messages (causing RERRs in other nodes) 2. Do not participate in following route request (A.1) 3. Do not relay data packets OR 1. Drop data packets 2. Set hop limit/TTL to 0/1 (causing a RERR) Table 1: Attack Tree: Save own resources Parameter Value Number of Nodes 50 Area X (m) 1500 Area Y (m) 300 Transmission Range Radius (m) 250 Traffic Model cbr Sending rate (packets/s) 4.0 Max. number of connections 20 Packet size (byte) 512 Simulation time (s) 900 Table 2: Simulation parameters the detection of modifications to routing data but not on the concealment of existing links. We have done a number of simulations that show how this behavior affects a MANET. The simulations were done using ns-2.1b8a and the DSR routing protocol. The scenario included 50 nodes moving in an area of 1500x300m according to the random waypoint model at speeds of 1ms and 20 m s with no pause time. Twenty of the nodes were CBR sources sending 4 packets per second. Details of the simulation parameters are given in table 2. These parameters are used for all following simulations. Figure 1 shows the results of these simulations. We have varied the number of selfish nodes from 0 to 50 (the total number of nodes in the network). It is obvious that the number of selfish nodes has a significant effect on the rate of packets that are successfully delivered in the network. Further the movement rate has a clear effect. The faster nodes move, the lower the delivery ratio becomes. Finally we see that at lower speeds nodes of case 3.1 are more detrimental to the network than those of type case 1.1, whereas at higher speeds there are no big differences. What explanations can be found for this? When the number of case-1.1 nodes rises in a Number of selfish nodes 0 10 20 30 40 50 D el iv er y ra tio % 0 20 40 60 80 100 Attack case 1.1 Node movement: 1 m/s Node movement: 20 m/s Number of selfish nodes 0 10 20 30 40 50 D el iv er y ra tio % 0 20 40 60 80 100 Attack case 3.1 Node movement: 1 m/s Node movement: 20 m/s Figure 1: Selfish attack simulation network, there are less nodes available for building up routes. So if no alternative route can be established, there is no route to the destination which means that packets have to be discarded. That reduces the delivery rate. When movement speed rises, the delivery ratio also diminishes as the network in general gets more fragile. But the network still has a reasonable chance of routing around the selfish nodes. This changes with type case3.1. Here the nodes behave correctly during the route discovery phase. Thus they can be included in regular routes, but then they start to drop all packets. This isn’t detected by DSR and no countermeasures are taken. So at a movement speed of 20ms only 10% of the selfish nodes push the probability of a successful packet delivery below 50%. Our simulations with AODV have revealed a similar behavior. This demonstrates clearly that an effective protection against selfish and malicious nodes is absolutely mandatory for ad hoc networks. 2 Motivation vs. Detection & Exclusion There are two approaches of dealing with selfish nodes. The first approach tries to give a motivation for participating in the network function. A typical system representing this approach is Nuglets by Hubeaux et al. [BH01, BH03]. The authors suggest to introduce a virtual currency called Nuglets that is earned by relaying foreign traffic and spent by sending own traffic. The major drawback of this approach is the demand for trusted hardware to secure the currency. There are arguments that tamper-resistant devices in general might be next to impossible to be realized [AK96, AK97]. A similar approach without the need of tamper-proof hardware has been suggested by Zhong et al. in [ZCY03]. Most of the existing work in this field concentrates on the second approach: detecting and excluding misbehaving nodes. The first to propose a solution to the problem of selfish (or as they call it ”misbehaving”) nodes in an ad hoc network were Marti, Giuli, Lai, and Baker in [MGLB00]. Their system uses a watchdog that monitors the neighboring nodes to check if they actually relay the data the way they should do. Then a component called pathrater will try to prevent paths which contain such misbehaving nodes. As they indicate in their paper, their detection mechanism has a number of severe drawbacks. Relying only on overhearing transmissions in promiscuous mode may fail due to a number of reasons. In case of sensor failure, nodes may be falsely accused of misbehavior. The second drawback is that selfish nodes profit from being recognized as misbehaving. The paths in the network are then routed around them, but there is no exclusion from service. We will later present more advanced sensors that will allow a better detection of selfish nodes. In [ZL00, ZLH03], the authors describe a distributed intrusion detection system (IDS) for MANETs that consists of the local components ”data collection”, ”detection”and ”response”, and of the global components ”cooperative detection”and ”global response”. Their architecture is very promising and similar to the one we use in our project, but they neglect the aspect how their local data collection should find out on incidents like dropped packets, concealed links, etc. Another system is the ”Collaborative Reputation Mechanism”or CORE [MM, MM02]. It is similar to the distributed IDS by Zhang et al. and consists of local observations that are combined and distributed to calculate a reputation value for each node. Based on this reputation, nodes are allowed to participate in the network or are excluded. In their work, the authors specify in detail how the different nodes should cooperate to combine the local reputation values to a global reputation and how they should react to negative reputations of nodes. For the actual detection of selfish nodes, they only refer to the work of Marti. A similar approach is conducted by Buchegger et al. with their system called CONFIDANT [BB02a, BB02b]. Again, they only marginally describe their detection mechanism and rely mostly on promiscuous overhearing.
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paper_title: Multiple Access in Ad-Hoc Wireless LANs with Noncooperative Stations

paper_content:

A class of contention-type MAC protocols (e.g., CSMA/CA) relies on random deferment of packet transmission, and subsumes a deferment selection strategy and a scheduling policy that determines the winner of each contention cycle. This paper examines contention-type protocols in a noncooperative an ad-hoc wireless LAN setting, where a number of stations self-optimise their strategies to obtain a more-than-fair bandwidth share. Two scheduling policies, called RT/ECD and RT/ECD-1s, are evaluated via simulation It is concluded that a well-designed scheduling policy should invoke a noncooperative game whose outcome, in terms of the resulting bandwidth distribution, is fair to non-self-optimising stations.
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paper_title: Detection and handling of MAC layer misbehavior in wireless networks

paper_content:

Wireless Medium Access Control (MAC) protocols such as IEEE 802.11 use distributed contention resolution mechanisms for sharing the wireless channel. In this environment, selfish hosts that fail to adhere to the MAC protocol may obtain an unfair share of the channel bandwidth. For example, IEEE 802.11 requires nodes competing for access to the channel to wait for a “backoff” interval, randomly selected from a specified range, before initiating a transmission. Selfish nodes may wait for smaller backoff intervals than well-behaved nodes, thereby obtaining an unfair advantage. We present modifications to the IEEE 802.11 protocol to simplify detection of such selfish hosts. We also present a correction scheme for penalizing selfish misbehavior. Simulation results indicate that our detection and correction schemes are successful in handling MAC layer misbehavior.
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paper_title: The Sybil Attack

paper_content:

Large-scale peer-to-peer systems face security threats from faulty or hostile remote computing elements. To resist these threats, many such systems employ redundancy. However, if a single faulty entity can present multiple identities, it can control a substantial fraction of the system, thereby undermining this redundancy. One approach to preventing these "Sybil attacks" is to have a trusted agency certify identities. This paper shows that, without a logically centralized authority, Sybil attacks are always possible except under extreme and unrealistic assumptions of resource parity and coordination among entities.
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paper_title: The sybil attack in sensor networks: analysis & defenses

paper_content:

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.
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paper_title: Ad-hoc on-demand distance vector routing

paper_content:

An ad-hoc network is the cooperative engagement of a collection of mobile nodes without the required intervention of any centralized access point or existing infrastructure. We present Ad-hoc On Demand Distance Vector Routing (AODV), a novel algorithm for the operation of such ad-hoc networks. Each mobile host operates as a specialized router, and routes are obtained as needed (i.e., on-demand) with little or no reliance on periodic advertisements. Our new routing algorithm is quite suitable for a dynamic self starting network, as required by users wishing to utilize ad-hoc networks. AODV provides loop-free routes even while repairing broken links. Because the protocol does not require global periodic routing advertisements, the demand on the overall bandwidth available to the mobile nodes is substantially less than in those protocols that do necessitate such advertisements. Nevertheless we can still maintain most of the advantages of basic distance vector routing mechanisms. We show that our algorithm scales to large populations of mobile nodes wishing to form ad-hoc networks. We also include an evaluation methodology and simulation results to verify the operation of our algorithm.
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paper_title: Secure routing in wireless sensor networks: attacks and countermeasures

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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.
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paper_title: An Empirical Study of Epidemic Algorithms in Large Scale Multihop Wireless Networks

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A bracket for a profile apparatus for block walls having a body, two spaced arms extending normally to the body, one of the arms having an adjustable screw. Apparatus for establishing a vertical in a block wall incorporates the bracket together with a tube to be set vertical and held against the wall by the bracket.
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paper_title: Wormhole Detection in Wireless Ad Hoc Networks

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A new and distinct variety of Valencia navel orange tree which is characterized by seedless fruit with a navel structure and has a very late maturity.
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paper_title: Authenticated Ad Hoc Routing at the Link Layer for Mobile Systems

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We have designed an authenticated link-level ad hoc routing protocol and integrated it with the Portland State University implementation of Mobile-IP. The routing protocol addresses link security issues. In our protocol, mobile nodes, as well as agents, broadcast ICMP router discovery packets. The router discovery packets are authenticated and bind the sender's MAC and IP addresses. Problems caused by tying IP subnet schemes to routing on radio links are eliminated. Security problems associated with ARP spoofing are also reduced. This link-level protocol is integrated with Mobile-IP on links where increased security is needed. The protocol replaces ARP, and may be integrated with higher-level multi-hop ad hoc routing protocols.
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paper_title: Highly-resilient, energy-efficient multipath routing in wireless sensor networks

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Previously proposed sensor network data dissemination schemes require periodic low-rate flooding of data in order to allow recovery from failure. We consider constructing two kinds of multipaths to enable energy efficient recovery from failure of the shortest path between source and sink. Disjoint multipath has been studied in the literature. We propose a novel braided multipath scheme, which results in several partially disjoint multipath schemes. We find that braided multipaths are a viable alternative for energy-efficient recovery from isolated and patterned failures.
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paper_title: Secure data transmission in mobile ad hoc networks

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The vision of nomadic computing with its ubiquitous access has stimulated much interest in the Mobile Ad Hoc Networking (MANET) technology. However, its proliferation strongly depends on the availability of security provisions, among other factors. In the open, collaborative MANET environment practically any node can maliciously or selfishly disrupt and deny communication of other nodes. In this paper, we present and evaluate the Secure Message Transmission (SMT) protocol, which safeguards the data transmission against arbitrary malicious behavior of other nodes. SMT is a lightweight, yet very effective, protocol that can operate solely in an end-to-end manner. It exploits the redundancy of multi-path routing and adapts its operation to remain efficient and effective even in highly adverse environments. SMT is capable of delivering up to 250% more data messages than a protocol that does not secure the data transmission. Moreover, SMT outperforms an alternative single-path protocol, a secure data forwarding protocol we term Secure Single Path (SSP) protocol. SMT imposes up to 68% less routing overhead than SSP, delivers up to 22% more data packets and achieves end-to-end delays that are up to 94% lower than those of SSP. Thus, SMT is better suited to support QoS for real-time communications in the ad hoc networking environment. The security of data transmission is achieved without restrictive assumptions on the network nodes' trust and network membership, without the use of intrusion detection schemes, and at the expense of moderate multi-path transmission overhead only.
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paper_title: Ariadne: a secure on-demand routing protocol for ad hoc networks

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An ad hoc network is a group of wireless mobile computers (or nodes), in which individual nodes cooperate by forwarding packets for each other to allow nodes to communicate beyond direct wireless transmission range. Prior research in ad hoc networking has generally studied the routing problem in a non-adversarial setting, assuming a trusted environment. In this paper, we present attacks against routing in ad hoc networks, and we present the design and performance evaluation of a new secure on-demand ad hoc network routing protocol, called Ariadne. Ariadne prevents attackers or compromised nodes from tampering with uncompromised routes consisting of uncompromised nodes, and also prevents a large number of types of Denial-of-Service attacks. In addition, Ariadne is efficient, using only highly efficient symmetric cryptographic primitives.
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paper_title: Exploring Message Authentication in Sensor Networks

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This paper explores the design space for message authentication in sensor networks. Several types of authentication are put into relation: end-to-end, hop-to-hop, and physical and virtual multipath authentication. While end-to-end authentication provides the highest and most general security level, it may be too costly or impractical to implement. On the other end of the security scale, hop-to-hop authentication can be implemented with little effort but provides security only to a highly restricted attacker. Multipath authentication provides an intermediate security level that may be appropriate for many applications of sensor networks, trading energy for security guarantees. Virtual multipaths offer an improvement, reducing energy demands while retaining crucial security properties of physical multipaths.
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paper_title: Intrusion Detection in Wireless Ad Hoc Networks

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Intrusion detection has, over the last few years, assumed paramount importance within the broad realm of network security and it has significant impact on wireless ad hoc networks. These networks do not have an underlying infrastructure and the network topology constantly changes. The inherently vulnerable characteristics of wireless ad hoc networks make them susceptible to attacks, and it may be difficult to control before any prevention works out. Secondly, with so much advancement in hacking, if attackers use sophisticated technology, they will eventually succeed in infiltrating the system. This makes it important to constantly or periodically monitor what is taking place on a system and look for suspicious behavior. Intrusion detection systems (IDS)monitor audit data, look for intrusions to the system, and initiate a proper response. In this paper, we present a method for determining critical path that use the distributed security scheme to find out the malicious node. The nodes with the help of the critical links will find out the malicious node using distributed security scheme and inform all the nodes about malicious node. The simulation results describe the details of the critical path test.
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paper_title: Mitigating routing misbehavior in mobile ad hoc networks

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This paper describes two techniques that improve throughput in an ad hoc network in the presence of nodes that agree to forward packets but fail to do so. To mitigate this problem, we propose categorizing nodes based upon their dynamically measured behavior. We use a watchdog that identifies misbehaving nodes and a pathrater that helps routing protocols avoid these nodes. Through simulation we evaluate watchdog and pathrater using packet throughput, percentage of overhead (routing) transmissions, and the accuracy of misbehaving node detection. When used together in a network with moderate mobility, the two techniques increase throughput by 17% in the presence of 40% misbehaving nodes, while increasing the percentage of overhead transmissions from the standard routing protocol's 9% to 17%. During extreme mobility, watchdog and pathrater can increase network throughput by 27%, while increasing the overhead transmissions from the standard routing protocol's 12% to 24%.
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paper_title: Intrusion Detection Techniques for Mobile Wireless Networks

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The rapid proliferation of wireless networks and mobile computing applications has changed the landscape of network security. The traditional way of protecting networks with firewalls and encryption software is no longer sufficient and effective. We need to search for new architecture and mechanisms to protect the wireless networks and mobile computing application. In this paper, we examine the vulnerabilities of wireless networks and argue that we must include intrusion detection in the security architecture for mobile computing environment. We have developed such an architecture and evaluated a key mechanism in this architecture, anomaly detection for mobile ad-hoc network, through simulation experiments.
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paper_title: CORE: A Collaborative Reputation Mechanism to enforce node cooperation in Mobile Ad hoc Networks

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Countermeasures for node misbehavior and selfishness are mandatory requirements in MANET. Selfishness that causes lack of node activity cannot be solved by classical security means that aim at verifying the correctness and integrity of an operation. We suggest a generic mechanism based on reputation to enforce cooperation among the nodes of a MANET to prevent selfish behavior. Each network entity keeps track of other entities’ collaboration using a technique called reputation. The reputation is calculated based on various types of information on each entity’s rate of collaboration. Since there is no incentive for a node to maliciously spread negative information about other nodes, simple denial of service attacks using the collaboration technique itself are prevented. The generic mechanism can be smoothly extended to basic network functions with little impact on existing protocols.
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paper_title: Sensors for Detection of Misbehaving Nodes in MANETs

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The fact that security is a critical problem when implementing mobile ad hoc networks (MANETs) is widely acknowledged. One of the different kinds of misbehavior a node may exhibit is selfishness. A selfish node wants to preserve its resources while using the services of others and consuming their resources. One way of preventing selfishness in a MANET is a detection and exclusion mechanism. In this paper, we focus on the detection and present different kinds of sensors that will find selfish nodes. First we present simulations that show the negative effects which selfish nodes cause in MANET. In the related work section we will analyze the detection mechanisms proposed by others. Our new detection mechanisms that we describe in this paper are called activity-based overhearing, iterative probing, and unambiguous probing. Simulation-based analysis of these mechanisms show that they are highly effective and can reliably detect a multitude of selfish behaviors. 1 Selfish nodes in MANETs Mobile ad hoc networks (MANETs) rely on the cooperation of all participating nodes. The more nodes cooperate to transfer traffic, the more powerful a MANET gets. But supporting a MANET is a cost-intensive activity for a mobile node. Detecting routes and forwarding packets consumes local CPU time, memory, network-bandwidth, and last but not least energy. Therefore there is a strong motivation for a node to deny packet forwarding to others while at the same time using their services to deliver own data. In table 1, we analyze different possibilities for a selfish node to save its own resources in a MANET based on the DSR routing protocol [JMHJ03, Pe01]. It uses the attack-tree notation proposed by Bruce Schneier [Sc99] that allows the analysis of different ways how an attacker can achieve his goal. Alternatives to reach a certain goal are denoted by OR, multiple steps that are necessary to reach a goal are denoted by AND. Using the numbers in the table, we can easily describe different attacks. For example, attack 3.1 stands for ”Drop data packets”. Whereas most of the attacks based on manipulations of routing data can be detected by the use of a secure routing protocol like Ariadne [HPJ02], SRP [PH02a, PH02b, PH02c, PHS02, PH03], ARAN [SDL02], or SAODV [Gu02, GA02], there remain two attacks in the attack tree that cannot be detected this easily. When nodes simply drop packets (case 1.1 and 3.1 in the attack tree), all of the secure routing protocols fail as they focus only on Attack tree: Save own resources OR 1. Do not participate in routing OR 1. Do not relay routing data OR 1. Do not relay route requests 2. Do not relay route replies 3. Set hop limit or TTL value in route request/reply to smallest possible value 2. Modify routing data/topology OR 1. Modify route request OR 1. Insert additional hops 2. Modify route reply OR 1. Replace own ID in returned route with detour leading through neighboring nodes 2. Return completely wrong route, provoking RERR and salvaging 3. Insert additional hops 4. Declare own ID in source route as external 2. Stop participation in current route AND 1. Provoke route error OR 1. Create arbitrary RERR messages 2. Do not send ACK messages (causing RERRs in other nodes) 2. Do not participate in following route request (A.1) 3. Do not relay data packets OR 1. Drop data packets 2. Set hop limit/TTL to 0/1 (causing a RERR) Table 1: Attack Tree: Save own resources Parameter Value Number of Nodes 50 Area X (m) 1500 Area Y (m) 300 Transmission Range Radius (m) 250 Traffic Model cbr Sending rate (packets/s) 4.0 Max. number of connections 20 Packet size (byte) 512 Simulation time (s) 900 Table 2: Simulation parameters the detection of modifications to routing data but not on the concealment of existing links. We have done a number of simulations that show how this behavior affects a MANET. The simulations were done using ns-2.1b8a and the DSR routing protocol. The scenario included 50 nodes moving in an area of 1500x300m according to the random waypoint model at speeds of 1ms and 20 m s with no pause time. Twenty of the nodes were CBR sources sending 4 packets per second. Details of the simulation parameters are given in table 2. These parameters are used for all following simulations. Figure 1 shows the results of these simulations. We have varied the number of selfish nodes from 0 to 50 (the total number of nodes in the network). It is obvious that the number of selfish nodes has a significant effect on the rate of packets that are successfully delivered in the network. Further the movement rate has a clear effect. The faster nodes move, the lower the delivery ratio becomes. Finally we see that at lower speeds nodes of case 3.1 are more detrimental to the network than those of type case 1.1, whereas at higher speeds there are no big differences. What explanations can be found for this? When the number of case-1.1 nodes rises in a Number of selfish nodes 0 10 20 30 40 50 D el iv er y ra tio % 0 20 40 60 80 100 Attack case 1.1 Node movement: 1 m/s Node movement: 20 m/s Number of selfish nodes 0 10 20 30 40 50 D el iv er y ra tio % 0 20 40 60 80 100 Attack case 3.1 Node movement: 1 m/s Node movement: 20 m/s Figure 1: Selfish attack simulation network, there are less nodes available for building up routes. So if no alternative route can be established, there is no route to the destination which means that packets have to be discarded. That reduces the delivery rate. When movement speed rises, the delivery ratio also diminishes as the network in general gets more fragile. But the network still has a reasonable chance of routing around the selfish nodes. This changes with type case3.1. Here the nodes behave correctly during the route discovery phase. Thus they can be included in regular routes, but then they start to drop all packets. This isn’t detected by DSR and no countermeasures are taken. So at a movement speed of 20ms only 10% of the selfish nodes push the probability of a successful packet delivery below 50%. Our simulations with AODV have revealed a similar behavior. This demonstrates clearly that an effective protection against selfish and malicious nodes is absolutely mandatory for ad hoc networks. 2 Motivation vs. Detection & Exclusion There are two approaches of dealing with selfish nodes. The first approach tries to give a motivation for participating in the network function. A typical system representing this approach is Nuglets by Hubeaux et al. [BH01, BH03]. The authors suggest to introduce a virtual currency called Nuglets that is earned by relaying foreign traffic and spent by sending own traffic. The major drawback of this approach is the demand for trusted hardware to secure the currency. There are arguments that tamper-resistant devices in general might be next to impossible to be realized [AK96, AK97]. A similar approach without the need of tamper-proof hardware has been suggested by Zhong et al. in [ZCY03]. Most of the existing work in this field concentrates on the second approach: detecting and excluding misbehaving nodes. The first to propose a solution to the problem of selfish (or as they call it ”misbehaving”) nodes in an ad hoc network were Marti, Giuli, Lai, and Baker in [MGLB00]. Their system uses a watchdog that monitors the neighboring nodes to check if they actually relay the data the way they should do. Then a component called pathrater will try to prevent paths which contain such misbehaving nodes. As they indicate in their paper, their detection mechanism has a number of severe drawbacks. Relying only on overhearing transmissions in promiscuous mode may fail due to a number of reasons. In case of sensor failure, nodes may be falsely accused of misbehavior. The second drawback is that selfish nodes profit from being recognized as misbehaving. The paths in the network are then routed around them, but there is no exclusion from service. We will later present more advanced sensors that will allow a better detection of selfish nodes. In [ZL00, ZLH03], the authors describe a distributed intrusion detection system (IDS) for MANETs that consists of the local components ”data collection”, ”detection”and ”response”, and of the global components ”cooperative detection”and ”global response”. Their architecture is very promising and similar to the one we use in our project, but they neglect the aspect how their local data collection should find out on incidents like dropped packets, concealed links, etc. Another system is the ”Collaborative Reputation Mechanism”or CORE [MM, MM02]. It is similar to the distributed IDS by Zhang et al. and consists of local observations that are combined and distributed to calculate a reputation value for each node. Based on this reputation, nodes are allowed to participate in the network or are excluded. In their work, the authors specify in detail how the different nodes should cooperate to combine the local reputation values to a global reputation and how they should react to negative reputations of nodes. For the actual detection of selfish nodes, they only refer to the work of Marti. A similar approach is conducted by Buchegger et al. with their system called CONFIDANT [BB02a, BB02b]. Again, they only marginally describe their detection mechanism and rely mostly on promiscuous overhearing.
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paper_title: Visualization of wormholes in sensor networks

paper_content:

Several protocols have been proposed to defend against wormholes in ad hoc networks by adopting positioning devices, synchronized clocks, or directional antennas. In this paper, we propose a mechanism, MDS-VOW, to detect wormholes in a sensor network. MDS-VOW first reconstructs the layout of the sensors using multi-dimensional scaling. To compensate the distortions caused by distance measurement errors, a surface smoothing scheme is adopted. MDS-VOW then detects the wormhole by visualizing the anomalies introduced by the attack. The anomalies, which are caused by the fake connections through the wormhole, bend the reconstructed surface to pull the sensors that are faraway to each other. Through detecting the bending feature, the wormhole is located and the fake connections are identified. The contributions of MDS-VOW are: (1) it does not require the sensors to be equipped with special hardware, (2) it adopts and combines the techniques from social science, computer graphics, and scientific visualization to attack the problem in network security. We examine the accuracy of the proposed mechanism when the sensors are deployed in a circle area and one wormhole exists in the network. The results show that MDS-VOW has a low false alarm ratio when the distance measurement errors are not large.
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paper_title: Using Directional Antennas to Prevent Wormhole Attacks

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Wormhole attacks enable an attacker with limited resources and no cryptographic material to wreak havoc on wireless networks. To date, no general defenses against wormhole attacks have been proposed. This paper presents an analysis of wormhole attacks and proposes a countermeasure using directional antennas. We present a cooperative protocol whereby nodes share directional information to prevent wormhole endpoints from masquerading as false neighbors. Our defense greatly diminishes the threat of wormhole attacks and requires no location information or clock synchronization.
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paper_title: Time synchronization for wireless sensor networks

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Recent advances in miniaturization and low-cost, low-power design have led to active research in large-scale networks of small, wireless, low-power sensors and actuators. Time synchronization is a critical piece of infrastructure in any distributed system, but wireless sensor networks make particularly extensive use of synchronized time. Almost any form of sensor data fusion or coordinated actuation requires synchronized physical time for reasoning about events in the physical world. However, while the clock accuracy and precision requirements are often stricter in sensor networks than in traditional distributed systems, energy and channel constraints limit the resources available to meet these goals. ::: New approaches to time synchronization can better support the broad range of application requirements seen in sensor networks, while meeting the unique resource constraints found in such systems. We first describe the design principles we have found useful in this problem space: tiered and multi-modal architectures are a better fit than a single solution forced to solve all problems; tunable methods allow synchronization to be more finely tailored to problem at hand; peer-to-peer synchronization eliminates the problems associated with maintaining a global timescale. We propose a new service model for time synchronization that provides a much more natural expression of these techniques: explicit timestamp conversions . ::: We describe the implementation and characterization of several synchronization methods that exemplify our design principles. Reference-Broadcast Synchronization achieves high precision at low energy cost by leveraging the broadcast property inherent to wireless communication. A novel multi-hop algorithm allows RBS timescales to be federated across broadcast domains. Post-Facto Synchronization can make systems significantly more efficient by relaxing the traditional constraint that clocks must be kept in continuous synchrony. ::: Finally, we describe our experience in applying our new methods to the implementation of a number of research and commercial sensor network applications.
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paper_title: Distributed deviation detection in sensor networks

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Sensor networks have recently attracted much attention, because of their potential applications in a number of different settings. The sensors can be deployed in large numbers in wide geographical areas, and can be used to monitor physical phenomena, or to detect certain events.An interesting problem which has not been adequately addressed so far is that of distributed online deviation detection in streaming data. The identification of deviating values provides an efficient way to focus on the interesting events in the sensor network.In this work, we propose a technique for online deviation detection in streaming data. We discuss how these techniques can operate efficiently in the distributed environment of a sensor network, and discuss the tradeoffs that arise in this setting. Our techniques process as much of the data as possible in a decentralized fashion, so as to avoid unnecessary communication and computational effort.
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paper_title: Localized fault-tolerant event boundary detection in sensor networks

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This paper targets the identification of faulty sensors and detection of the reach of events in sensor networks with faulty sensors. Typical applications include the detection of the transportation front line of a contamination and the diagnosis of network health. We propose and analyze two novel algorithms for faulty sensor identification and fault-tolerant event boundary detection. These algorithms are purely localized and thus scale well to large sensor networks. Their computational overhead is low, since only simple numerical operations are involved. Simulation results indicate that these algorithms can clearly detect the event boundary and can identify faulty sensors with a high accuracy and a low false alarm rate when as many as 20% sensors become faulty. Our work is exploratory in that the proposed algorithms can accept any kind of scalar values as inputs, a dramatic improvement over existing works that take only 0/1 decision predicates. Therefore, our algorithms are generic. They can be applied as long as the "events" can be modelled by numerical numbers. Though designed for sensor networks, our algorithms can be applied to the outlier detection and regional data analysis in spatial data mining.
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paper_title: Efficient tracing of failed nodes in sensor networks

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In sensor networks, nodes commonly rely on each other to route messages to a base station. Although this practice conserves power it can obscure the cause of a measurement outage in a portion of the network. For example, when a base station ceases to receive measurements from a region of nodes it can't immediately determine whether this is because of the destruction of all the nodes in that region (due to an enemy attack, for example) or merely the result of the failure of a few nodes bearing much of the routing load. Previous solutions to this problem typically consist of re-running the route-discovery protocol, a process that can be quite expensive in terms of the number of messages that must be exchanged. We demonstrate that the topology of the network can be efficiently conveyed to the base station allowing for the quick tracing of the identities of the failed nodes with moderate communication overhead. Our algorithms work in conjunction with the existing functions of the network, requiring the nodes to send no additional messages.
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paper_title: Denial of Service in Sensor Networks

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Sensor networks hold the promise of facilitating large-scale, real-time data processing in complex environments, helping to protect and monitor military, environmental, safety-critical, or domestic infrastructures and resources, Denial-of-service attacks against such networks, however, may permit real world damage to public health and safety. Without proper security mechanisms, networks will be confined to limited, controlled environments, negating much of the promise they hold. The limited ability of individual sensor nodes to thwart failure or attack makes ensuring network availability more difficult. To identify denial-of-service vulnerabilities, the authors analyzed two effective sensor network protocols that did not initially consider security. These examples demonstrate that consideration of security at design time is the best way to ensure successful network deployment.
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paper_title: The sybil attack in sensor networks: analysis & defenses

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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.
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Title: Attacks and Countermeasures in Sensor Networks: A Survey

Section 1: Introduction
Description 1: Introduce WSNs, their applications, characteristics, and the significance of security. Outline the paper's focus on attacks and countermeasures classified by the OSI model.

Section 2: Physical Layer
Description 2: Provide an overview of the physical layer and its importance. Discuss potential attacks in this layer and countermeasures.

Section 3: Attacks in the Physical Layer
Description 3: Detail the types of attacks targeting the physical layer, including device tampering, eavesdropping, and jamming.

Section 4: Countermeasures in the Physical Layer
Description 4: Describe the methods to counter physical layer attacks, including access restriction and encryption.

Section 5: MAC Layer
Description 5: Explain the role of the MAC layer in WSNs. Highlight the types of attacks and appropriate countermeasures in this layer.

Section 6: Attacks in the MAC Layer
Description 6: Elaborate on specific MAC layer attacks, such as traffic manipulation and identity spoofing.

Section 7: Countermeasures in the MAC Layer
Description 7: Present countermeasures for MAC layer attacks, focusing on misbehavior detection and identity protection.

Section 8: Network Layer
Description 8: Introduce the network layer's functions and its susceptibility to attacks. Discuss typical network layer attacks and countermeasures.

Section 9: Attacks in the Network Layer
Description 9: Detail network layer attacks, including false routing, packet replication, black hole, sinkhole, selective forwarding, and wormhole attacks.

Section 10: Countermeasures in Network Layer
Description 10: Outline strategies to mitigate network layer attacks, such as routing access restriction, false routing information detection, and wormhole detection.

Section 11: Application Layer
Description 11: Discuss the application layer's services and potential attacks. Provide countermeasures to protect application data.

Section 12: Attacks in the Application Layer
Description 12: Detail specific application layer attacks, including clock skewing, selective message forwarding, and data aggregation distortion.

Section 13: Countermeasures in the Application Layer
Description 13: Present countermeasures for application layer attacks, focusing on data integrity protection and data confidentiality protection.

Section 14: Discussion
Description 14: Summarize the interplay and combination of different types of attacks across layers, and highlight areas needing further research.

Section 15: Conclusion
Description 15: Recap the survey's findings on WSN attacks and countermeasures, emphasizing the importance of understanding layered security vulnerabilities and solutions.