A Layered Approach to Cognitive Radio Network Security: A Survey

1. A Layered Approach to Cognitive Radio Network Security: A Survey By Deanna Hlavacek

2. Mobile Data Forecast for North America 2010 - 2015

3. Spectrum Allocation • Licensed • Military, public safety, commercial services • Lightly Licensed • RADAR, communication systems • Opened for mixed use in 2004 • Unlicensed • Available for network setup by public or private entities • More spectrum for unlicensed use • Spectrum sharing – no interference

4. Cognitive Radio • Software Defined • Two types • Policy Radio -- Preloaded Policies • Learning Radio -- Artificial Intelligence • Learning Radio

5. Cognitive Cycle Spectrum Decision Open Spectrum Information Cognitive Radio Environment Channel Capacity RF Stimuli RF Stimuli Transmitted Spectrum Analysis Open Spectrum Information Spectrum Sensing Spectrum Sensing Signal

6. Security Considerations Confidentiality Security Model Non-repudiation Authentication Availability Integrity

7. Physical Layer • Primary User Attack • An external attacker emulates the signal of the Primary User to force other users from the channel. This may be for malicious or selfish reasons. • Objective Function Attack • Attacker manipulates transmission rate parameters so cognitive engine will calculate results that are biased towards the attacker’s interests.

8. Physical Layer • Jamming • Jammer maliciously sends packets to hinder legitimate use of the spectrum. • Overlapping Secondary User • A geographical region may contain coexisting, overlapping multiple secondary networks. A malicious user in one network may transmit signals that cause harm to the primary and secondary users of both networks.

9. Data Link Layer • Byzantine • Attacker sends false local spectrum sensing results to neighbors or fusion center. This causes the receiver to make wrong spectrum sensing decisions. • Control Channel Jamming • Control channels facilitate the cooperation among cognitive radio users. Jamming of the control channel causes confusion for the network.

10. Data Link Layer • Control Channel Saturation • Based on the fact that if a cognitive radio is unable to complete negotiations during the limited time of the control phase, the radio defers from transmission during the next data phase.

11. Network Layer • Ripple • The wrong channel information is provided so that the other nodes in the area change their channel. The attacker’s intent is to cause the false information to be passed hop by hop and cause the network to enter a confused state. • HELLO Flood • Node broadcasts HELLO loud enough so all nodes think it is a neighbor. Packets are lost since the node is far away.

12. Network Layer • Wormhole • Attacker tunnels messages or pieces of messages to different parts of network to replay them • Sybil • Attacker sends packets as different identities. This subverts the trust system. • HELLO Flood • Node broadcasts HELLO loud enough so all nodes think it is a neighbor. Packets are lost since the node is far away.

13. Network Layer • Sinkhole • Attacker advertises itself as the best route.Attacker can then do selective forwarding in which packets are modified or discarded.

14. Transport Layer • Key Depletion • With the great number of session keys generated in a cognitive radio network, it becomes more likely a session key will be repeated. Repetitions of a key can provide an avenue of exploitation to break the underlying cipher system.

15. Application Layer • Cognitive Radio Virus • The cognitive radio network is asvulnerable to viruses, and they can effectradio function and learning.

16. Cross Layer • Jelly Fish • The attack is based on the dual role of the radio as a router with forwarding behavior. The attack targets closed-loop flows that are responsive to network conditions like delay and loss. • Lion • Attack utilizes the PUE attack at PHY layer to disrupt the TCP. TCP continues to create logical connections and sending packets. The packets will timeout, and TCP retransmits. Retransmit timer doubles with backoff. This results in delays and packet loss.

17. Cross Layer • Routing Information Jamming • A malicious node causes the targeted node to initiate spectrum hand off before the routing information is exchanged leaving the node without the ability to communicate. • Small Backoff Window • Node decreases its own backoff window size so it has a better chance of getting the channel.

18. Conclusion • Cognitive radio network is vulnerable to attacks on other wireless technologies • Some attacks have been solved in other areas • Some attacks are unique to the CRN and need to be solved • See the paper for proposed mitigation techniques for the attacks