Secure Routing in wireless sensor networks: attacks and countermeasures

Secure Routing in wireless sensor networks:attacks and countermeasures Chris Karlof and David Wagner University of California at Berkeley 1st IEEE International Workshop on Sensor Network Protocols and Applications, 2003 발표: 장준혁, 최준철

Contents • Introduction: wireless sensor network • Problem statement • Attacks on sensor network routing • Attacks on specific sensor network protocols • Countermeasures • Conclusion

Wireless Sensor Network(WSN) • Applications • Fire monitoring, protecting wild animals, military purpose • Deployment • Sensing • Network construction • Data aggregation • Restricted resources • Environments(assumptions) • Base station • Global information • Transmission range • Mobility • Resource constraints Sensor Node Sensor Field Sink Node

Sensor Node <Mica mote> <Power consumption>

Sensor Network Routing • Power consumption dominates network lifetime • Mostly, sensor nodes are not repaired or reused • 2 weeks ~ a few years • How many messages are used? • = How long does the network alive? •  Sensor routing protocols • Flooding, proactive(DSDV), reactive(AODV), clustering(LEACH) • The routing protocols are not designed for security and traditional methods are hard to use • This paper suggests • Threat models and security goals • Countermeasures • Design consideration

WSN vs. Ad-hoc Wireless Networks • Similarity • Support Multi-hop networking • Differences • Sensor : Supports Specialized communication patterns • Many-to-One • One-to-Many • Local Communication • Sensor nodes more resource constrained than Ad-hoc nodes • Public key cryptography not feasible • Higher level of trust relationship among sensor nodes • In-network processing, aggregation, duplication elimination

Problem Statement • Trust Requirements • Insecure Radio links • Base station(trusted), nodes(untrusted) • None tamper resistant • Adversary can access all key, data, code • Threat Models • Based on device capability • Mote-class attacker / Laptop-class attacker • Based on attacker type/location • Outside attacks / Inside attacks

Security Goal • Responsibility • Link layer: Integrity, authenticity, and confidentiality • Routing protocol: Availability • Application: replay attack • Outsider adversaries • Conceivable to achieve these goals • Insider adversaries • These goals are not fully attainable -> Graceful degradation

Attack Model • Spoofed, altered, or replayed routing information • Selective forwarding • Sinkhole attacks** • Sybil attacks • Wormholes attacks • HELLO flood attacks** • Acknowledgement spoofing • Attacker wants to: • Steal information through the data flows • Break the functionality of the sensor network

B A1 A2 A3 A4 Attack Model • Spoofed, altered or replayed routing information • May be used for loop construction, attracting or repelling traffic, extend or shorten source route • Selective forwarding • A malicious node behaves like a black hole • Refuse to forward certain messengers, selective forwarding packets or simply drop them • Sinkhole attacks • Attacker creates metaphorical sinkhole by advertising for example high quality route to a base station • Almost all traffic is directed to the fake sinkhole

Attack Model • The Sybil Attack • Forging of multiple identities - having a set of faulty entities represented through a larger set of identities. • Significant threat to location aware routing protocols • An adversary node can be in more than one place at once • Wormholes • Tunneling of messages over alternative low-latency links, • e.g. confuse the routing protocol, create sinkholes. etc. 그림: 애드혹(Ad Hoc) 네트워크에서의 위치정보 기반의 웜홀(Wormhole) 탐지 기법, 이규호 외, 정보과학회, 2006

Attack Model • HELLO flood attack • 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 • TinyOS beaconing • Directed Diffusion • Geographic routing

Attacks on specific protocols • TinyOS beaconing • Base station broadcast Route update(beacon) periodically, Nodes received the update and mark the base station as parent and broadcast it • Breadth First Spanning Tree rooted at a base station • Routingupdates are not authenticated

Attacks on TinyOS protocols • Spoofing a routing update • Bogus and replayed routing information (such like “I am station”) send by an adversary can easily pollute the entire network • Routing loops can easily be created by mote-class adversaries

Attacks on TinyOS protocols • Wormhole / Sinkhole attack • Two colluding powerful laptop-class nodes, one near the base station and one near the targeted area • The first node forwards routing updates through worm hole • The second node create sinkhole by rebroadcasting the routing update in the targeted area

Attacks on TinyOS protocols • HELLO flood attack • Broadcast a routing update loud enough to reach the entire network by using a powerful transmitter • Every node marks the adversary as its parent • Most nodes will be likely out of normal radio range

Attacks on specific protocols • Directed diffusion • A data-centric routing algorithm for drawing information out of a sensor network

Attacks on Directed diffusion protocols • Suppression • Cloning • Path influence • Selective forwarding and data tempering

Attacks on specific protocols • Geographic Routing • GPSR (Greedy Perimeter Stateless Routing) • Greedy forwarding routing each packet to the neighbor closest to the destination • GEAR (Geographic and Energy Aware Routing) • GEAR weighs the choice of the next hop by both remaining energy and distance from the target

Attacks on Geographic Routing protocols • Sybil Attack • Surrounding each target using non-existent nodes by using Sybil attack. Adversary maximizes chances for placing herself on the path of data flow • Forge location advertisements • Advertise her location in a way to place herself on the path of a known flow • Forge other node’s location to create routing loops

Countermeasures • Authentication and encryption • Prevents the majority of outsider attacks • False routing information, selective forwarding, sinkhole attacks, sybil attacks, ACK spoofing • Can’t prevent to tunnel or amplify legitimate message • Wormhole attacks, HELLO flood atacks • Can’t prevent insider attacks

Countermeasures • Insider attacks • Using a globally shared key allows an insider to masquerade as any node • Verifing identities might be done using Public key cryptography, but this is beyond the capabilities of sensor nodes • Share a unique symmetric key with a trusted base station • Two nodes verify each other by using some protocol and establish a shared key • Using that key, pair of noes can implement authenticated and encrypted link between them • Base station reasonably limit the number of neighbors

Countermeasures • Wormhole and Sinkhole attacks • These are very difficult to defend since detecting and verifying is extremely difficult • Difficult to retrofit existing protocols with defenses against these attack • Best solution is to carefully design routing protocols • Geographic routing protocol • Resistant to wormhole and sinkhole attacks • Do not construct topology with initiation. Construct on demand • Difficult to create a sinkhole and easy to detect wormhole

Countermeasures • Selective Forwarding • Multipath routing can be used to counter these types of selective forwarding attacks • Messages routed over n paths whose nodes are completely disjoint are completely protected against selective forwarding attacks involving at most n compromised nodes • Allowing nodes to dynamically choose a packet’s next hop probabilistically from a set of possible candidates

Conclusion • Currently proposed routing protocols for sensor networks are insecure • Link layer encryption and authentication, multipath • routing, identity verification, bidirectional link • verification and authenticated broadcast is important • Cryptography is not enough for insiders and laptopclass • adversaries, careful protocol design is needed as • well

Secure Routing in wireless sensor networks: attacks and countermeasures