The Inherent Security of Routing Protocols in Ad Hoc and Sensor Networks Tanya Roosta (EECS, Berkeley) In Collaboration With: Sameer Pai (ECE, Cornell) Phoebus Chen (EECS, Berkeley) Prof. Shankar Sastry (EECS, Berkeley) Prof. Stephen Wicker (ECE, Cornell) April 2, 2008

2 Outline Introduction Problem Setup Attack Scenarios Simulation Setup and Parameters Results Current/Future Work

3 Introduction Generally the focus of routing protocols for sensor networks: – Energy-efficiency – Guaranteed throughput – Usually involves a non-adversarial setting Sensor networks are deployed and left unattended – Susceptible to attacks – Must design networks with security in mind Our work – Determine the statistical impact of different attacks on sensor network routing – Determine performance of different families of routing protocols under particular attack scenarios

4 Problem Setup We abstract away the details of specific attacks and specific routing protocols Instead we focus on characterizing the statistics of attacks on different classes of routing algorithms Routing Protocols: – Single-path & Multi-path routing protocols – Deterministic and Probabilistic routing protocols Attack Scenarios – Adversary has compromised some number of nodes within the sensor network and has subverted their normal operations – Mote-class, insider attackers alter the data and forward it as normal – Attacks differ by the locations of the attackers within the network topology

5 Single-Path Routing Deterministic Single-path Routing – Minimum-weight path routing – Edges are assigned weights – Packets sent on path minimizing sum of weights on edges contained in the path Probabilistic Single-path Routing – Like a directed random walk on a graph – Each node assigns a probability to each neighbor node (e.g. uniform assignment) – Packet sent to next-hop neighbor chosen based on the assigned probability – Achieves load-balancing in a statistical sense

6 Multi-path Routing Protocols Deterministic Multi-path Routing – k-shortest node-disjoint paths – k-shortest edge-disjoint paths Probabilistic Multi-path Routing – Each node in the network broadcasts packets to all neighbors with some probability – Extreme case is probabilistic flooding

7 Attack Scenarios Uniformly distributed attack: – The attacker compromises a number of k nodes uniformly at random.

8 Attack Scenarios Random walk attack: – The attacker chooses a node to compromise uniformly at random and then performs a directed random walk towards the periphery of the network.

9 Attack Scenarios Spatial attack: – The attacker chooses a node to compromise uniformly at random and also compromises all nodes within a set preset radius.

10 Simulator Secure Sensor Network Routing Simulator SSNRS – Built in MATLAB to evaluate routing protocols in the attack scenarios – Discrete packet-time marching simulator – Allows for use of: Different channel models Routing topologies Routing protocols Attack scenarios

11 Parameters Used in Simulations

12 Baseline Average Energy Expenditure

13 Results: Uniform Attack

14 Results: Directed Random Walk

15 Results: Spatial Attack

16 Results Routing performance falls sharply with increasing number of uncooperative nodes (insider attackers) The performance degrades for most families of routing protocols Single-path routing performs worst with increasing number of uncooperative nodes Multi-path routing performs best, but comes at an increased energy cost

17 Results (cont.) The uniformly distributed attackers scenario is most detrimental to successful end-to-end packet delivery Spatial attacks are highly clustered, attacking nodes have a lower probability of being on a path from the source to the destination Random walk attacks have performance degradation results between the other two attack scenarios Probabilistic routing protocols are best to preserve confidentiality.

18 Current and Future Work Problem: We need a way to mitigate misbehavior in ad hoc and sensor networks – Nodes not forwarding data correctly (uncooperative nodes) during routing can cause major problems – Only those nodes that are behaving correctly (cooperating) should be authorized to have access to the data Solution: A trust system for wireless ad hoc and sensor networks – A trust value is a networked node’s belief (probability) in the ability of other nodes in the network to pass necessary data from this node while preserving data integrity and confidentiality A local metric for predicting the future behavior of other networked nodes Assists any node in distinguishing reliable forwarding nodes (cooperative nodes) from unreliable forwarding ones (uncooperative nodes) Goal: To develop robust trust systems for wireless ad hoc and sensor networks

19 References 1. “The Inherent Security of Routing Schemes in Ad Hoc and Sensor Networks”. Tanya Roosta, Sameer Pai, Phoebus Chen, Shankar Sastry, Stephen Wicker. In proceedings of the IEEE Globecom 2007, Washington D.C USA.