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Distributed Detection Of Node Replication Attacks In Sensor Networks By Bryan Parno, Adrian Perrig and Virgil Gligor Presenter: Kirtesh Patil Acknowledgement: Slides on Paper originally provided by Bryan Parno, Adrian Perrig and Virgil Gligor Sensor Networks • Wireless sensor networks contain thousands of nodes • Each node has limited processing, storage capacity and power • Low Cost • Easy to deploy – No Tamper proof Replication Attack • Capture one node – pressure, voltage and temperature sensing not built-in to detect intrusion – Read memory • Replicate nodes – same IDs – Affects data aggregation protocols – Replicated nodes can be used to kick legitimate nodes out (node-revocation protocol) Introduction Problem Statement Solution 1 Solution 2 Evaluation Outline • • • • • Introduction Problem Statement and Previous Work Solution Evaluation Discussion Discussion Introduction Problem Statement Solution 1 Solution 2 Evaluation Discussion Assumptions • Adversary can’t deploy nodes with arbitrary ID – paper assumes n/w implements required safeguards • Adversary has limited node capturing capability • Cloned node has at least one legitimate node in neighborhood (Can be eliminated) • All node know their geographical location and node are primarily stationary Introduction Problem Statement Solution 1 Solution 2 Evaluation Discussion Objectives • Detect node replication with high probability • Secure against adaptive adversary – Unpredictable to adversary – No central point of failure • Minimize communication overhead Introduction Problem Statement Solution 1 Solution 2 Evaluation Discussion Previous Approaches • Centralized scheme – Each node sends location to central base station – Central base station examines list for conflicts – Revocation: flood network with authenticated revocation message – Disadvantages: • Vulnerable to single point failure – Compromise base station – Interfere with its communication • Node surrounding base station – undue routing of traffic • Revocation can be delayed – Advantages: 100% detection Introduction Problem Statement Solution 1 Solution 2 Evaluation Previous Approaches (Contd.) • Local Detection Scheme – Neighbor try to detect replicated nodes – Fails to detect distributed node replicated in disjoint neighborhood Discussion Introduction Problem Statement Solution 1 Solution 2 Evaluation Discussion Emergent Properties • They are properties that only emerge through collective action of multiple nodes • Advantages: – No Central Point of Failure – Attractive approach to thwart unpredictable and adaptive adversary Introduction Problem Statement Solution 1 Solution 2 Evaluation Simple Approach • Node-To-Network Broadcast – Each node broadcast location information – 100% detection – Assumption: Broadcast reaches all nodes • Attacker can easily jam or interfere with communication Discussion Introduction Problem Statement Solution 1 Solution 2 Evaluation Discussion Simple Approach (Contd.) • Deterministic Multicast – Node sends location to neighbors – Neighbors choose witness and forward location to them – Problem: • Predictable – attacker can jam all messages to witnesses • Witnesses become target to subversion Introduction Problem Statement Solution 1 Solution 2 Evaluation Discussion Approach Overview STEP1: Announce location – Sign and broadcast location to neighbors STEP 2: Detect Replicas – Use Emergent properties – Ensure at least one witness receives two conflicting locations STEP 3: Revoke replicas – Flood network with conflicting location claims (signed) Introduction Problem Statement Solution 1 Solution 2 Evaluation Discussion Randomized Multicast Protocol STEP 2 • Witness chosen randomly • Each neighbor chooses n d witnesses • So n neighbor send location to n witnesses • By Birthday Paradox – if there are clones then location conflict will occur. w R • Probability of detection PDetect 1 e n 2 Introduction Problem Statement Solution 1 Solution 2 Evaluation Discussion Line Selected Multicast • Use routing topology of network to select witnesses • All the intermediate nodes between neighbor and witness check for conflict • Geometric probability says replicated nodes will be detected Introduction Problem Statement Solution 1 Solution 2 Evaluation Discussion Line Selected Multicast Detection Introduction Problem Statement Solution 1 Solution 2 Evaluation Discussion Line Selected Multicast Detection Y Introduction Problem Statement Solution 1 Solution 2 Evaluation Discussion Line Selected Multicast Detection Y With five line segments per point : 95% Introduction Problem Statement Solution 1 Solution 2 Evaluation Discussion Theoretical Communication Overhead Detection Scheme Centralized Detection Randomized Multicast Line Selected Multicast Average # of Messages / Nodes O( n ) O( n ) O (n) Introduction Problem Statement Solution 1 Solution 2 Evaluation Communication Overhead Discussion Introduction Problem Statement Solution 1 Solution 2 Topologies Evaluation Discussion Introduction Problem Statement Solution 1 Solution 2 Evaluation Discussion Probability of Detection in Irregular Topologies Introduction Problem Statement Solution 1 Solution 2 Evaluation Discussion Timing Issue And Masked-Replication • How often to perform detection 1. Every T unit of time – node forgets previous claims 2. Time slots • • Time slots based on ID Witness remember claims during time slot • Adversary captures neighbors – Solution: pseudo-neighbors – neighbors ask for location claim Introduction Problem Statement Solution 1 Solution 2 Evaluation Discussion Conclusion And Future Work • Use of emergent properties to tackle node replication – High probability of detection – Resilient to adaptive adversary – Minimum communication overhead • Scheme assumes captured nodes follow protocol – Implicit sampling to detect nodes that suppress or drop messages Introduction Problem Statement Solution 1 Solution 2 Evaluation Comments and Questions? Discussion