1. Wireless Sensor Networks (WSN’s) Security Lecture 13

2. Mote A very low cost low power computer Monitors one or more sensors
External Memory
Digital I/O ports
Radio Transceiver
Analog I/O Ports
Microcontroller
A/D
D/A
Sensor
A very low cost low power computer
Monitors one or more sensors
A Radio Link to the outside world
Are the building blocks of Wireless Sensor Networks (WSN)

3. Wireless Sensor Network
“A wireless sensor network (WSN) is a wireless network consisting of spatially distributed autonomous devices using sensors to cooperatively monitor physical or environmental conditions, such as temperature, sound, vibration, pressure, motion or pollutants, at different locations.” - Wikipedia

4. Wireless Sensor Networks
Formed by hundreds or thousands of motes that communicate with each other and pass data along from one to another
Research done in this area focus mostly on energy aware computing and distributed computing

5. WSN Applications Environmental/Habitat monitoring Acoustic detection
Seismic Detection
Military surveillance
Inventory tracking
Medical monitoring
Smart spaces
Process Monitoring

6. TinyOS
What is TinyOS
open-source operating system
wireless embedded sensor networks
component-based architecture
Developed at UCB in collaboration with Intel Research
Current Stable Version is
TinyOS 2.0 (T2) released on 6/11
Main Ideas –
Low complexity
Conserve power – sleep as frequently as possible
Written in nesC – next generation C compiler

7. Different Targets
mica
mica2
mica2dot
micaz
telos
telosb
rene2 pc

8. Problems applying traditional network security techniques
Sensor devices are limited in their energy, computation,
and communication capabilities.
• Sensor nodes are often deployed in open areas, thus
allowing physical attack.
• Sensor networks closely interact with their physical
environments and with people, posing new security
problems.
• In-network processing requires intermediate nodes to
access and modify information.

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

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

11. DoS in Sensor Networks [Wood et al.]
What is DoS?
Attack that reduces or eliminates the network’s ability to perform its function.
E.g., hardware failures, software bugs, resource exhaustion, etc.
What are the possible DoS attacks at various protocol layers? (Explained in the following slides)

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

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

14. Network layer: attacks
Misdirection.
An adversary misdirects packets by identity deception through replaying routing information. With such identity deception, the adversary is capable of launching harmful and hard-to-detect attacks to misdirect traffic
Gray/black holes.
In a black hole attack, the malicious node replies to every routing request saying that it has a route to the given destination. So, unsuspecting nodes start sending data to the destination through the black hole. This way a black hole diverts most of the traffic in the network to itself, and later dumps it. A gray hole attack is a variation of the black hole attack, where the malicious node is not initially malicious, it turns malicious sometime later.

15. Network layer: defenses
Authorization.
Only authorized nodes participate in routing.
Need authentication mechanisms.
Monitoring.
Monitor node behavior.
Probing.
Redundancy.

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

17. Security Focus in WSN’s
Communication security in sensor networks.
Data classification and related security threats.
Location-based security mechanism.

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

19. Target sensor net architecture
Localized algorithms.
Local broadcast.
Mobile code.

20. Security threats Insertion of malicious code.
Interception of messages with node location information.
Interception of application data.
Injection of false data.
Lower risk.

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

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

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

24. Performance Cost of encryption/decryption. Energy considerations.
Rockwell WINS node.

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

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

27. Deployment and platform
Heterogeneous deployment.
Mica motes with TinyOS.
Base stations.
Aggregation points.

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

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

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

31. References CMPE259-Sensor Networks - Katia Obraczka
CMPE259-Sensor Networks - Katia Obraczka
Shali Jain et al., Advanced Algorithm for Detection and Prevention of Cooperative Black and Gray Hole Attacks in Mobile Ad Hoc Networks, 2010 International Journal of Computer Applications (0975 – 8887), Volume 1(7).
Guoxing Zhan et. Al. TARF:A Trust-Aware Routing Framework for Wireless Sensor Networks