Anthony D. Wood

Denial of service in sensor networks

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.

JAM: a jammed-area mapping service for sensor networks

Preventing denial-of-service attacks in wireless sensor networks is difficult primarily because of the limited resources available to network nodes and the ease with which attacks are perpetrated. Rather than jeopardize design requirements which call for simple, inexpensive, mass-producible devices, we propose a coping strategy that detects and maps jammed regions. We describe a mapping protocol for nodes that surround a jammer which allows network applications to reason about the region as an entity, rather than as a collection of broken links and congested nodes. This solution is enabled by a set of design principles: loose group semantics, eager eavesdropping, supremacy of local information, robustness to packet loss and failure, and early use of results. Performance results show that regions can be mapped in 1-5 seconds, fast enough for real-time response. With a moderately connected network, the protocol is robust to failure rates as high as 25 percent.

EnviroTrack: towards an environmental computing paradigm for distributed sensor networks

Distributed sensor networks are quickly gaining recognition as viable embedded computing platforms. Current techniques for programming sensor networks are cumbersome, inflexible, and low-level. We introduce EnviroTrack, an object-based distributed middleware system that raises the level of programming abstraction by providing a convenient and powerful interface to the application developer geared towards tracking the physical environment. EnviroTrack is novel in its seamless integration of objects that live in physical time and space into the computational environment of the application. Performance results demonstrate the ability of the middleware to track realistic targets.

DEEJAM: Defeating Energy-Efficient Jamming in IEEE 802.15.4-based Wireless Networks

Jamming is a very effective denial-of-service attack that renders most higher-layer security mechanisms moot - yet it is often ignored in WSN design. We show that an interrupt jamming attack is simple to perpetrate in software using a MICAz mote, is energy efficient and stealthy for the jammer, and completely disrupts communication. Solutions are needed to mitigate this insider threat even if more powerful attackers are not thwarted. We present DEEJAM, a novel MAC-layer protocol for defeating stealthy jammers with IEEE 802.15.4-based hardware, to address this problematic area. It layers four defensive mechanisms to hide communication from a jammer, evade its search, and reduce its impact. Given the difficulty of modeling the physical layer accurately in simulation, we evaluate DEEJAM instead on the MICAz mote. We show the performance of the protocol against successively more complex attacks: interrupt jamming, activity jamming, scan jamming, and pulse jamming. Results show that DEEJAM defeats the otherwise devastating interrupt jammer, and achieves a packet delivery ratio of 88% in the presence of a pulse jammer. To the best of our knowledge, this work is the first to confront multiple types of jamming on common WSN hardware with solutions that are shown empirically to enable continued communication despite an ongoing attack.

A Taxonomy for Denial-of-Service Attacks in Wireless Sensor Networks

Wireless sensor networks (WSNs) are transitioning to real-world applications, where they face attacks already experienced by the Internet and wireless ad hoc networks. One such attack is that of denial-of-service ( DOS), which we believe will only become more prevalent as sensor networks become more pervasive and accessible. With the inherent resource limitations of WSN devices, they are particularly susceptible to the consumption and destruction of these scarce resources. We present a DOS attack taxonomy to identify the attacker, his capabilities, the target of the attack, vulnerabilities used, and the end result. We survey vulnerabilities in WSNs and give possible defenses. Protecting WSNs against DOS attacks—while remaining low-cost and flexible—is a primary research challenge that bears further exploration.

An Assisted Living Oriented Information System Based on a Residential Wireless Sensor Network

This paper deals with a new medical information system called Alarm Net designed for smart healthcare. Based on an advanced Wireless Sensor Network (WSN), it specifically targets assisted-living residents and others who may benefit from continuous and remote health monitoring. We present the advantages, objectives, and status of the system built at the Department of Computer Science at UVA. Early results of the prototype suggest a strong potential for WSNs to open new research perspectives for ad hoc deployment of multi-modal sensors and improved quality of medical care

An entity maintenance and connection service for sensor networks

In this paper, we present a middleware architecture for coordination services in sensor networks that facilitates interaction between groups of sensors which monitor different environmental events. It sits on top of the native routing infrastructure and exports the abstraction of mobile communication endpoints maintained at the locations of such events. A single logical destination is created and maintained for every environmental event of interest. Such destinations are uniquely labeled and can be used for communication by application-level algorithms for coordination and sensory data management between the different event locales. For example, they may facilitate coordination, in a distributed intrusion scenario, among nodes in the vicinity of the intruders.We evaluate our middleware architecture using GloMoSim, a wireless network simulator. Our results illustrate the success of our architecture in maintaining event-related communication endpoints. We provide an analysis of how architectural and network dependent parameters affect our performance. Additionally we provide a proof of concept implementation on a real sensor network testbed (Berkeleys MICA Motes).

Realistic Applications for Wireless Sensor Networks

Military surveillance, home health care or assisted living, and environmental science are three major application areas for wireless sensor networks. Revolutionary changes are possible in these application areas by using wireless sensor networks. To show the breadth and advantages of this technology, design and implementation details are presented for three systems, one in each of these three application domains. Key research challenges and the approaches taken to address them are highlighted. Challenges requiring significantly improved solutions are also identified. These systems and others like them provide significant evidence for the utility of wireless sensor networks.

SenQ: An Embedded Query System for Streaming Data in Heterogeneous Interactive Wireless Sensor Networks

Interactive wireless sensor networks (IWSNs) manifest diverse application architectures, hardware capabilities, and user interactions that challenge existing centralized [1], or VM-based [2] query system designs. To support in-network processing of streaming sensor data in such heterogeneous environments, we created SenQ, a multi-layer embedded query system. SenQ enables user-driven and peer-to-peer in-network query issue by wearable interfaces and other resource-constrained devices. Complex virtual sensors and user-created streams can be dynamically discovered and shared, and SenQ is extensible to new sensors and processing algorithms. We evaluated SenQs efficiency and performance in a testbed for assisted-living, and show that on-demand buffering, query caching, efficient restart and other optimizations reduce network overhead and minimize data latency.

AMSecure: secure link-layer communication in TinyOS for IEEE 802.15.4-based wireless sensor networks

General Terms: Security, Design, Performance