1-1 CMPE 259 Sensor Networks Katia Obraczka Winter 2005 Security

1-2 Announcements r Hw3 due today. r Project presentations tomorrow from 4- 7pm. r Project reports due tomorrow by midnight.

1-3 Security in sensor networks

1-4 Security in sensor networks r For many sensor network applications, security is critical. m Public safety, special operations, healthcare, etc. r Sensor network protocols should incorporate security mechanisms in the original design.

1-5 DoS in Sensor Networks [Wood et al.] r What is DoS? m Attack that reduces or eliminates the network’s ability to perform its function. m E.g., hardware failures, software bugs, resource exhaustion, etc. r Paper looks at protocol layers and possible DoS attacks.

1-6 Physical layer r Attacks: m Jamming. m Tampering. r Defenses: m Jamming: Spread-spectrum techniques. Lower duty cycle with priority messages. Alternate modes of communication. m Tampering: “Self-destruction” Hiding nodes.

1-7 Link layer r Attacks: m Collision induction. m Battery exhaustion. m Unfairness. r Defenses: m Collision induction.. Fairness. Error correcting codes (?).Small frames. Collision detection. Collision-free MAC. m Battery exhaustion. Rate limitation. Streamlined protocols.

1-8 Network layer: attacks r “Neglect and greed”. r “Homing”. r Misdirection. r Gray/black holes.

1-9 Network layer: defenses r Authorization. m Only authorized nodes participate in routing. Need authentication mechanisms. m Monitoring. Monitor node behavior. m Probing. m Redundancy.

1-10 Transport layer r Attacks: m Flooding. m Desynchronization. Message fabrication to get end points out of sync. r Defenses: m Flooding: Limit number of connections. Challenges/puzzles to clients. m Desynchronization: Authenticate all messages (including header fields)

1-11 Sample protocol vulnerabilities r Adaptive rate control [Woo et al.] m MAC layer modifications to m Preference to route-through traffic. m Vulnerabilities? r RAP [Lu et al.] m Similar vulnerability. m Differentiated services can be exploited by attacker.

1-12 “On Communication Security…” [Slijepcevic et al.]

1-13 Focus r Communication security in sensor networks. r Data classification and related security threats. r Location-based security mechanism.

1-14 Types of data r Mobile code. r Sensor node location. r Application data. r Goals: m Minimize security-related energy consumption. m Different protection levels.

1-15 Target sensor net architecture r Localized algorithms. r Local broadcast. r Mobile code.

1-16 Security threats r Insertion of malicious code. r Interception of messages with node location information. r Interception of application data. r Injection of false data. Lower risk.

1-17 Security architecture r Symmetric key encryption. m All messages encrypted. r Three security levels: m Level I: mobile code. m Level II: node location information. m Level III: application data. r Encryption strength: m Level I > level II > level III. r Encryption algorithm with adjustable strength (number of rounds).

1-18 Security architecture (cont’d) r Group keys. r Every user: set of keys, pseudorandom generator, and seed. r Periodically and synchronously, nodes change keys.

1-19 Security levels r Level I uses strongest encryption for mobile code injection. m 32 rounds. r Level II: m Location-based keys. Different for different “cells”. Protect network from compromised keys. r Level I: m Weakest security. m 22 rounds.

1-20 Performance r Cost of encryption/decryption. r Energy considerations. m Rockwell WINS node.

1-21 “Secure Routing…” [Karlof et al.]

1-22 Focus r Routing security in sensor networks. r Problem: m Current routing protocols for sensor networks do not consider security. m Vulnerable to attacks. m Not easy to make these protocols secure.

1-23 Contributions r Threat models and security goals for sensor network routing. r Two new attacks: sinkhole and HELLO floods. r Security analysis of routing and topology control algorithms. r Attacks against these protocols. r Countermeasures and design issues for secure routing in sensor networks.

1-24 Deployment and platform r Heterogeneous deployment. r Mica motes with TinyOS. r Base stations. r Aggregation points.

1-25 Sensor- and ad-hoc networks r Traffic considerations: m Ad hoc networks exhibit more general patterns. m Sensor networks: Many-to-one. One-to-many. Local. r Capabilities. m Sensor nodes are typically more limited. r Trust relationships. m E.g., to perform aggregation, duplicate pruning, etc.

1-26 Attacks r Spoofed, altered, replayed routing information. r Selective forwarding. m Black/gray hole. r Sinkhole. r Sybil. m Single nodes presents multiple id’s to others. r Wormhole. r HELLO flood. r (Link-layer) ACK spoofing.

1-27 Countermeasures r Outsider attacks: m Link layer encryption and authentication. m Shared keys. r Insider attacks: m Identity verification. m Multipath routing. m Bi-directional link verification. m Limiting number of neighbors. r Sinkhole and wormhole attacks are harder to circumvent. m Design routing protocols where these attacks are ineffective. m E.g., geographic routing. ???