1. A Distributed Security Framework for Heterogeneous Wireless Sensor Networks Presented by Drew Wichmann Paper by Himali Saxena, Chunyu Ai, Marco Valero, Yingshu Li, Raheem Beyah 1

2. Wireless Sensor Network (WSN) Security Applications Attacks – Sinkhole – Wormhole – DoS – Jamming – Sybil – Hello Flood Defense Mechanisms 2

3. Memory Constraints Mica2 mote – 4KB RAM – 128KB program memory 60KB for Operating System 45.26KB Code Dissemination Tool 7.2KB Link Layer Security 88% of memory consumed 3

4. Proposal Distributed Security Framework (DSF) which can detect and defend against all known attacks efficiently A warning mechanism can inform other clusters to install defense mechanisms for potential attacks in advance, thus reducing the impact caused by attacks The security framework is modular and scalable, thus defense mechanisms for new or future attacks can be easily added 4

5. Assumptions Base station and Gateway nodes tamper proof Attacker has regular node capabilities Those within transmission range are at higher risk Gateway Nodes have enough memory to store all defense schemes No false positives 5

6. Network Model Heterogeneous Network – Gateway Nodes – Regular Nodes Divide into clusters Communication – Gateway nodes require only single hop – Regular nodes use multi-hop to communicate with gateway nodes 6

7. Threat Model Two scenarios for attack – Single cluster – Multiple clusters The attacker can change position A compromised node has all material available 7

8. Problem Definition Goal – Significantly reduce an attack’s effectiveness There are a set of attacks, A = {A 1, A 2, …, A n } For every attack A i, there exists a defense scheme D i For every defense scheme D i, the program size is P i Each regular node has an available program memory of – Can only store a subset S of D 8

9. Problem Definition (continued) Assign weight W ji to an attack A i for a gateway node G j W ji represents the possibility of the attack A i occurring in G j Knapsack Problem: 9

10. DSF ARCHITECTURE The security framework to efficiently defend against all known attacks 10

11. Routing Protocol Gateway nodes calculate routes for each pair Regular nodes periodically send current state If reports are not received on time, then the regular node is assumed dead Gateway level uses Destination Sequenced Distance Vector (DSDV) 11

12. Choosing the Defense Mechanism Subset 12

13. Warning Messages When an attack is detected, send a warning W k W k = { A i, G s, WW k, T k } Each gateway node maintains a received warning list L j Keeps one entry per (A i, G s ) Then the likelihood of each attack is calculated 13

14. Propagate the subset Solve: Send the new defense mechanism images for S Use Seluge to transmit the images Protects this cluster from new attacks With the warning system, can enable defense of future attacks in other clusters 14

15. Security Framework Workings 15

16. Performance Analysis Parameters: Metrics – Success Rate – Energy Consumption 16

17. Performance Analysis Three schemes – Distributed Security Framework (DSF) – One Security Scheme (OSS) – Multiple Security Schemes (MSS) 17

18. Success Rate 18

19. Success Rate 19

20. Energy Use 20

21. Energy Use 21

22. Effect of Mobile Attacker Speed 22

23. Conclusion Dynamically use available memory to provide security from multiple attacks Warning scheme can enable prevention of future attacks Simulation results confirm DSF performs well Future work – Individual sensor subsets – Gateway node compromising – False positives and negatives – Implementation on real sensors – Thrashing Attacks 23

24. Questions?