Secure Routing in Wireless Sensor Networks: Attacks and Countermeasures

Chris Karlof David WagnerUniversity of Califonia at Berkeley

Paper review and Present byRun dong

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

Routing protocols Layer 3 protocols

determine the routing path and transmit the packets reliably

Traditional routing protocols RIP (routing information protocol)

Distance vector

OSPF (open shortest path first) Link state

BGP

Mobile Ad-hoc Network protocols On demand vs table driven

WSN Routing Protocols

Current Routing Protocols Goals Low Energy

Minimize communication Radio cost more than instructions executed Aggregate data in network

Low Node Duty Cycle Shut down nodes when possible

Robust Adapt to unpredictable environment without intervention

Scalable Rely on localized algorithms – no centralized control

Low Latency Must meet application latency and accuracy requirements

Small Footprint Must run on hardware with severe memory and computational

power constraints

Overview 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 Assumption about underlying network Different Threat Models Security goal in this setting

Problem statement Assumption about underlying network1. radio link are insecure (easily eavesdropping)

2. sensor nodes are not tamper resistant

3. The physical and MAC layers are susceptible to direct attack

4. Base station is trustworthy

5. Aggregation points may be trusted in certain protocols Different Threat Models Security goal in this setting

Problem statement Assumption about underlying network Different Threat Models1. Mote class vs Laptop class

2. Outsider vs insider Security goal in this setting

Problem statement Assumption about underlying network Threat Models Security goal in this setting1. The goal of conventional network is reliable delivery of

messengers

2. Sensor network need in-network processing (aggregation, compression, duplicate elimination)

3. Confidentiality Protection against Replay of data packets should better handled by higher level

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

Attacks model Spoofed, altered, or replayed routing information Create Loops Attract or repel network traffic Extend or shorten source routes, Generate false error messages Partition network Selective forwarding 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 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 Wormholes tunneling of messages over alternative low-latency links, e.g. confuse the routing protocol, create sinkholes. etc. Exploit routing race condition

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 General typical sensor routing protocol type:

Flooding Gradient Clustering and Cellular Geographic Energy Aware

TinyOS beaconing Directed diffusion Geographic routing Minimal cost forwarding Cluster-head- LEACH Rumor routing Energy conserving topology maintenance

TinyOS beaconing Base station broadcast Route update(beacon)

periodly, Nodes received the update and mark the base station as parent and broadcast it

Relevent Attack mode Bogus routing information Selective forwarding Sinkholes Sybil Wormholes Hello floods

TinyOS beacon

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

Spoof information

TinyOS beacon

Tunnel packets received in one place of the network and replay them in another place

The attacker can have no key material. All it requires is two transceivers and one high quality out-of-band channel

Wormhole & sinkhole Combination

Adapted from Chris Karlof and David Wagner's WSNPA slides

TinyOS beacon

Most packets will be routed to the wormhole

The wormhole can drop packets directly (sinkhole)

or more subtly selectively forward packets to avoid detection

Adapted from Chris Karlof and David Wagner's WSNPA slides

Wormhole & sinkhole Combination

TinyOS beacon

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

Hello flood attack

Directed diffusion Data and Application Specific Content based naming Interest distribution 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

Data propagation and reinforcement Reinforcement to single path delivery. Multipath delivery with probabilistic forwarding. Multipath delivery with selective quality along different paths.

Directed diffusion 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 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 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->A3->C

Geographic routing 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 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 Relevant attack mode Sinkhole attack

Mote-class adversary advertising cost zero anywhere in network

Hello flood attack Bogus routing informaiton Selective forwarding wormholes

LEACH 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 Relative attack mode Hello floods

Cluster-head selection based on signal strengh what mean a powerful advertisement can make the malicious attacker be it’s cluster-head.

Sybil attack Combined with hello floods if nodes try to randomly select

cluster-head instead of strongest signal strength.

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

Energy conserving topology maintenance 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 are 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 Relevant attack mode for GAF Bogus routing information

Broadcast high ranking discovery messages, then can use some selective forwarding attack

Sybil & Hello floods Target individual grids by a high ranking discovery messages with a non-

existent node, frequently advertisements can disable the whole network by making most node sleep

Energy conserving topology maintenance 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 Relevant attack mode for SPAN Hello floods

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 attacksProtocol Relevant Attacks

TinyOS 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.

Establish link keys using a trusted base station. Verifies the bidirectionality of links and prevents Sybil attacks and HELLO floods

Multipath and probabilistic routing limits effects of selective forwarding

Countermeasures 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 clustering-based 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.