1. A survey of Routing Attacks in Mobile Ad Hoc Networks Bounpadith Kannhavong, Hidehisa Nakayama, Yoshiaki Nemoto, Nei Kato, and Abbas Jamalipour Presented by: Holly Bennett 11/8/07

2. Intro Mobile Ad Hoc Networks (MANET) –Group of mobile devices –No predefined infrastructure –No centralized administration –Advantages: Mobility Low cost No need for existing infrastructure –Users: Disaster relief Emergency operations Military service Maritime communications Vehicle networks Campus networks Robot networks Etc

3. Routing Methodologies Reactive Routing Protocol –Ad Hoc On Demand Distance Vector AODV S wants to send a packet to D S does not have a route to D S sends a routing request RREQ to all its neighbors They either return a fresh path to D or forward the RREQ to their neighbors. Once the RREQ reaches D it returns a route reply RREP

4. Routing Methodologies Proactive Routing Protocols –Optimized Link State Routing OLSR Key concept: multipoint relay MPR, to reduce overall traffic Two types of messages: –Hello message to all neighbors, contains the nodes address and a list of all its one hop neighbors –The hello message gives each node a complete two-hop topology –Second type of message Topology Control TC messages –Only sent out by MPR nodes and contains the list of the senders MPR selector –Allows each node to learn the partial network topology and they can build a route to any node MPR Selection –In OLSR a node selects as its MPR set the set of nodes that can reach all its two-hop neighbors.

5. Attacks and Countermeasures Flooding Attack –Objective: exhaust network resources, overall bandwidth, and individual nodes resources of computational and battery power. –In AODV attacking node A sends out a large number of RREQs for a route to a non-existent node. –Countermeasures Calculate rate of neighbors RREQs, block if they exceed threshold Can not stop flooding below threshold and could block valid node if A is spoofing real nodes. Use statistical analysis to detect varying rates of flooding

6. Attacks and Countermeasures Blackhole Attack –Obj: Attacking node A returns fake routing information, causing the source node to choice a route through A, the attacker can then misuse or drop messages as it sees fit. –Countermeasures Introduce route confirmation requests CREQ and route confirmations reply CREP Intermediate nodes return RREPs and send CREQs to the next-hop node in the route to D, that node can send a CREP to S if it has a route to D. Can not defend against collusion between attacking nodes that returns false CREPs that validate the false RREPs. Proposal for a statistical analysis that compares destination sequence numbers to compare RREPs

7. Attacks and Countermeasures Link Withholding Attack –Obj: Attacker does not advertise a link to a specific node or group of nodes. –Countermeasures: Nodes listen for the TC message from the MPR node they selected, if they do not hear one that MPR node is rated suspicious and additional MPR nodes are selected. Again the countermeasure can be defeated by collusion if A2 drops the TC message created by A1

8. Attacks and Countermeasures Link Spoofing Attack –Obj: A attacking link advertises links to non-neighbors, by faking links to the two-hop neighbors of S, A can become one of its MPR nodes, and then manipulate traffic. –Countermeasures: Equip nodes with GPS and calculate whether two nodes could really have a link. Another solution is to include the 2-hop neighbors in the Hello message, this gives every node a 3-hop topology of the network, less expensive then special hardware, but is defeated by spoofing outside of 3-hops

9. Attacks and Countermeasures Replay Attack –Obj: Attacker records another nodes control messages and resends them later. Can be used to spoof another node or just disrupt routing. –Countermeasures: Add time stamp and asymmetric key to messages Reject old messages as suspicious

10. Attacks and Countermeasures Wormhole Attack –Obj: Two colluding attackers have a high speed link between them. Any RREQs that pass through the colluding nodes A1 and A2 will appear to cross the shortest path because of the high-speed link. This will cause S to send all messages to D through the compromised links A1 and A2. –Countermeasures: Packet leashes, temporal and geographical. These prevent a packet from moving too far too fast.

11. Attacks and Countermeasures Colluding Misrelay Attacks –Obj: Two colluding attackers modify or drop packets –Countermeasures: An acknowledgment system could detect this but will increase overhead. Another solution is to increase transmission power twice to detect the colluding attackers. However even if we increase the transmission power K times, K+1 attackers can drop packets.

12. Summary The advantages of the MANET are allowing them to be deployed much rapidly at low cost in a variety of applications. Security is often necessary, and the weaknesses of a MANET need to be considered. The major weaknesses are the constrained bandwidth, processing power and battery power. The article presented a survey of the various attacks currently considered against MANETs and summarized defenses that have been developed.