1. Surviving Attacks on Disruption- Tolerant Networks without Authentication John Burgess, George Dean Bissias, Mark Corner, Brian Neil Levine University of Massachusetts, Amherst

2. Goal Understand DTN vulnerability Attack analysis Experimental evaluation

3. Disruption Tolerant Networks Networking for intermittently connected nodes Rural Internet Urban blind spots Sparse sensor networks Connectivity on a spectrum

4. Unique Vulnerability Measured by packet delivery rate Nodes physically unsecured Traditional defenses are inappropriate: graph theoretical results are limited identity management not always practical

5. Undisturbed Decimated Attack strength Weak Strong Network impact Attack Universe Weak attacks: random node selection easy to evaluate Strong attacks: optimal node selection strong attack NP-hard to evaluate

6. Outline Attack Strategies Data Experimental Results Conclusion

7. Attacks: Weak Nodes chosen at random Attack defined by enumerating strategies Remove Node Drop all packets Flood packets Routing table falsification ACK counterfeiting

8. Attacks: Strong Intractable to determine optimal attack set Throughput is difficult metric to analyze Even simple metrics lead to NP-hard problem Instead, greedily remove vertices that most lower temporal connectivity

9. Data: DieselNet 40 buses 802.11 protocol 60 days of traces Transmission events feed a simulator Various routing protocols tested

10. Data: Haggle 41 devices in human mobility experiment Bluetooth 3 days of traces Haggle connections more frequent than DieselNet Haggle traces broken down to better match DieselNet

11. Experiments: weak attack Evaluated delivery rate via given routing protocol subject to given attack strategy Used DieselNet data only ReplicativeForwarding Metric based MaxPropMaxForw RandomRandPropRandForw Routing Protocols Attack Strategies Remove node Drop all Flooding Routing table Falsification ACK counterfeiting

12. Experiments: weak attack MaxProp Minimum delivery rate above 20% ACK counterfeiting is most effective attack

13. Experiments: ACK Counterfeiting Devise an ACK counterfeiting defense ACKs should propagate after packets Drop ACK if you haven’t seen packet yet Defense improves minimum packet delivery rate Drop All attack just as effective as ACK counterfeiting

14. Experiments: strong attack Seek to establish the validity of greedy attack Find best k vertices in terms of temporal reachability via brute force evaluation for small k Compare brute force results to greedy approach Evaluate greedy attack for larger values of k Evaluate both DieselNet and Haggle

15. Haggle: Brute vs. Greedy Experiments: strong attack For temporal reachability- best 5 nodes to remove almost always the same as 5 greedy choices Results for DieselNet similar

16. Experiments: strong attack Haggle: greedy attack Displays roughly the same resilience to attack at DieselNet Packet delivery rate degrades more slowly as more nodes are

17. Conclusion DTNs have unique susceptibility to attack Susceptibility understood with attack analysis Experiments on real traces show attack efficacy