Secure Routing in Wireless Sensor Networks Attacks and

Secure Routing in Wireless Sensor Networks: Attacks and Countermeasures Chris Karlof David Wagner University of Califonia at Berkeley Paper review and Present by Run dong

Outline n n n Overview & Background Statement of routing security problem Attacks on sensor network routing Attacks on specific sensor network protocols Countermeasures

Routing protocols n Layer 3 protocols n n determine the routing path and transmit the packets reliably Traditional routing protocols n RIP (routing information protocol) Ø n OSPF (open shortest path first) Ø n n Link state BGP Mobile Ad-hoc Network protocols n n Distance vector On demand vs table driven WSN Routing Protocols

Current Routing Protocols Goals n Low Energy Ø Minimize communication Ø Ø n Rely on localized algorithms – no centralized control Low Latency Ø n Adapt to unpredictable environment without intervention Scalable Ø n Low Node Duty Cycle Shut down nodes when possible Robust Ø n Radio cost more than instructions executed Aggregate data in network Must meet application latency and accuracy requirements Small Footprint Ø Must run on hardware with severe memory and computational power constraints

Overview n n Wireless sensor network cannot depend on many of the resources available to traditional networks for security Current sensor routing protocols are not designed for security and be insecure, mostly optimized for the limited capabilities of the nodes Analysis current protocols to find attacks and suggest countermeasures and design consideration The effective solution for secure routing is to design such sensor routing protocols with security in mind

Problem statement n n n Assumption about underlying network Different Threat Models Security goal in this setting

Problem statement n 1. 2. 3. 4. 5. n n Assumption about underlying network radio link are insecure (easily eavesdropping) sensor nodes are not tamper resistant The physical and MAC layers are susceptible to direct attack Base station is trustworthy Aggregation points may be trusted in certain protocols Different Threat Models Security goal in this setting

Problem statement n n Assumption about underlying network Different Threat Models 2. Mote class vs Laptop class Outsider vs insider n Security goal in this setting 1.

Problem statement n n n 1. 2. 3. Assumption about underlying network Threat Models Security goal in this setting The goal of conventional network is reliable delivery of messengers Sensor network need in-network processing (aggregation, compression, duplicate elimination) Confidentiality Protection against Replay of data packets should better handled by higher level

Attacks model n n n n Spoofed, altered, or replayed routing information Selective forwarding Sinkhole attacks Sybil attacks Wormholes attacks HELLO flood attacks Acknowledgement spoofing

Attacks model n Spoofed, altered, or replayed routing information Ø Create Loops Attract or repel network traffic Extend or shorten source routes, Generate false error messages Partition network n Selective forwarding Ø Ø Ø Ø Blackhole: refuse to forward certain messengers and simply drop them Either “in-path” or “beneath path” by deliberately jamming, (unique pair key to init FH or spread spectrum will prevent this) Follow the path of least resistance and attempt to include itself on the actual data path flow

Attacks model n Ø Ø Ø n Ø Ø Sinkhole attacks Lure nearly all traffic from a particular area through a compromised node Makes selective forwarding trivial Specialized communication pattern cause this problem( base station mode) Sybil attack forging of multiple identities -- having a set of faulty entities represented through a larger set of identities. Sybil Attack undermines assumed mapping between identity to entity and hence number of faulty entities

Attack model n Wormholes Ø tunneling of messages over alternative low-latency links, e. g. confuse the routing protocol, create sinkholes. etc. Exploit routing race condition n Hello flood attack Ø Ø Ø n Ø an attacker sends or replays a routing protocol’s hello packets with more energy Acknowledgement spoofing Spoof link layer acknowledgement to trick other nodes to believe that a link or node is either dead or alive

Attacks on specific protocols General typical sensor routing protocol type: n Ø Ø Ø n n n n Flooding Gradient Clustering and Cellular Geographic Energy Aware Tiny. OS beaconing Directed diffusion Geographic routing Minimal cost forwarding Cluster-head- LEACH Rumor routing Energy conserving topology maintenance

Tiny. OS beaconing n n Base station broadcast Route update(beacon) periodly, Nodes received the update and mark the base station as parent and broadcast it Relevent Attack mode Ø Ø Ø Bogus routing information Selective forwarding Sinkholes Sybil Wormholes Hello floods

Tiny. OS beacon Spoof information Bogus and replayed routing information (such like “I am base station”) send by an adversary can easily pollute the entire network.

Tiny. OS beacon Wormhole & sinkhole Combination Ø Tunnel packets received in one place of the network and replay them in another place Ø The attacker can have no key material. All it requires is two transceivers and one high quality out-of-band channel Adapted from Chris Karlof and David Wagner's WSNPA slides

Tiny. OS beacon Wormhole & sinkhole Combination Ø Most packets will be routed to the wormhole Ø The wormhole can drop packets directly (sinkhole) Ø or more subtly selectively forward packets to avoid detection Adapted from Chris Karlof and David Wagner's WSNPA slides

Tiny. OS beacon Hello flood attack Ø A Laptop class adversary that can retransmit a routing update with enough power to be received by the entire network Adapted from Chris Karlof and David Wagner's WSNPA slides

Directed diffusion n Data and Application Specific Content based naming Interest distribution Ø Interests are injected into the network from base station. Interval specifies an event data rate. Interest entry also maintains gradients. Data flows from the source to the sink along the gradient n Data propagation and reinforcement Ø Ø Ø Reinforcement to single path delivery. Multipath delivery with probabilistic forwarding. Multipath delivery with selective quality along different paths.

Directed diffusion n Ø Ø Ø Ø Relevant attack Suppression- by spoof negative reinforcement Cloning- by replay information with malicious listed as a base station Path influence- by spoof positive or negative reinforcements and bogus data events Selective forwarding and data tampering- by above attack method to put the malicious node in the data flow Wormholes attack Hello floods Sybil attack

Geographic routing n n Greedy geographic query routing technique Cost function based on destination location and neighbor node energies used to determine next hop Improvement over Directed Diffusion’s interest flooding technique Restricted broadcast within sampling region

Geographic routing n Ø Ø Relevant attack Sybil attack Bogus routing information Selective forwarding No wormholes and sinkholes attack An adversary may present multiple identities to other nodes. The Sybil attack can disrupt geographic and multi-path routing protocols by “being in more than one place at once” and reducing diversity. From B->C, now will go through B->A 3 ->C

Geographic routing n Ø Ø Relevant attack Sybil attack Bogus routing information Selective forwarding No wormholes and sinkholes attack From B->D, A forge a wrong information to claim B is in (2, 1), so C will send packets back to B which cause loop at last.

Minimum cost forwarding n n Is an backoff-based cost field algorism for efficiently forwarding packets from senor nodes to a base station. Once the field is established, the message, carrying dynamic cost information, flows along the minimum cost path in the cost field. Each intermediate node forwards the message only if it finds itself on the optimal path for this message based on the message’s cost states. A=110, will select B

Minimum cost forwarding n Relevant attack mode Ø Sinkhole attack Ø Ø Ø Mote-class adversary advertising cost zero anywhere in network Hello flood attack Bogus routing informaiton Selective forwarding wormholes

LEACH n Ø Ø Ø Low-Energy Adaptive Clustering Hierarchy randomized, self-configuration Low energy media access control Cluster-head collect data and perform processing then transmit to BS Relevant attack mode Hello floods Selective forwarding Sybil attack

LEACH n Relative attack mode Ø Hello floods Ø Ø Cluster-head selection based on signal strengh what mean a powerful advertisement can make the malicious attacker be it’s cluster-head. Sybil attack Ø Combined with hello floods if nodes try to randomly select cluster-head instead of strongest signal strength.

Rumor Routing n n Designed for query/event ratios between query and event flooding Lower the energy cost of flooding Observation: Two lines in a bounded rectangle have a 69% chance of intersecting, 5 line more than 99% Event Source

Rumor routing

Rumor routing n Ø Ø Ø Relevant attack mode Bogus routing information Selective forwarding Sinkholes Sybil wormholes

Energy conserving topology maintenance n Ø Ø Ø GAF-Geographical Adaptive Fidelity Identifies equivalent nodes for routing based on location information Dense nodes deployment, Turns off unnecessary nodes Physical space is divided into equal virtual size squares. Each nodes know it’s location and nodes with a square equivalent Sleeping, discovery, active state Each grid square has one active node Nodes are ranked with respect to current state and expected lifetime

Energy conserving topology maintenance n Relevant attack mode for GAF Ø Bogus routing information Ø Ø Broadcast high ranking discovery messages, then can use some selective forwarding attack Sybil & Hello floods Ø Target individual grids by a high ranking discovery messages with a nonexistent node, frequently advertisements can disable the whole network by making most node sleep

Energy conserving topology maintenance n Ø Ø Ø Ø SPAN An energy-efficient coordination algorism for topology maintenance Traffic only routed by coordinator Backbone for routing fidelity is build by coordinators A node becomes eligible to be a coordinator if two of its neighbors cannot reach other directly or via one or two coordinators. Random backoff for delay coordinator announcement Utility and energy level decide coordinator selection by adjusting the backoff time Hello messengers being broadcasted periodically.

Energy conserving topology maintenance n Relevant attack mode for SPAN Ø Hello floods Ø Broadcast n Hello messages with fake coordinators and neighbors which will preventing nodes from becoming coordinators when they should. then can use some selective forwarding attack

Summary of attacks Protocol Relevant Attacks Tiny. OS beaconing Bogus routing information, selective forwarding, sinkholes, Sybil, wormholes, HELLO floods Directed diffusion and its multipath variant Bogus routing information, selective forwarding, sinkholes, Sybil, wormholes, HELLO floods Geographic routing (GPSR, GEAR) Bogus routing information, selective forwarding, Sybil Minimum cost forwarding Bogus routing information, selective forwarding, sinkholes, wormholes, HELLO floods Clustering based protocols (LEACH, TEEN, PEGASIS) Selective forwarding, HELLO floods Rumor routing Bogus routing information, selective forwarding, sinkholes, Sybil, wormholes Energy conserving topology maintenance (SPAN, GAF, CEC, AFECA) Bogus routing information, Sybil, HELLO floods

Countermeasures • Link layer security with a globally shared key can prevent the majority of outsider attacks: bogus routing information, Sybil, selective forwarding, sinkholes. However, it provides little protection against insiders, HELLO floods, and wormholes. n Establish link keys using a trusted base station. Verifies the bidirectionality of links and prevents Sybil attacks and HELLO floods n Multipath and probabilistic routing limits effects of selective forwarding

Countermeasures n n n Wormholes are difficult to defend against. Can be mounted effectively by both laptop-class insiders and outsiders. Good protocol design is the best solution: geographic and clusteringbased protocols hold the most promise. Wormholes are ineffective against these protocols Authenticated broadcast and flooding are important primitives. Nodes near base stations are attractive to compromise. Clustering-based protocols and overlays can reduce their significance

Conclusion • Conclusion: Link layer security is important, but cryptography is not enough for insiders and laptop-class adversaries: careful protocol design is needed as well.