Securing Future Wireless Networks: Challenges and Strategies Pandurang Kamat Wade Trappe

Talk Overview Security has been one of the great detractors for wireless technologies (and the Internet, too!) We have a chance to consider security as we redesign the network Think about the questions: –Should security be considered separately from the network? –What benefits are there if we integrate security into the network? –Should we reevaluate the definition of security? –How private do we really want our lives? This talk will not focus on classical “Internet Security” but on “Wireless Security”

Through the Looking Glass, the Wireless World Key properties and differentiators that make wireless desirable –Ubiquity –Mobility –Resource adaptability –Portability –Affordability –Platform heterogeneity MPC8260 TMS320C6701 XC2V6000 FPGA 100BaseT Ethernet Megarray Connector- 244 Configurable I/O pins

Reevaluating the Security Paradigm Confidentiality IntegrityAvailability System (CIA) Paradigm Data Confidentiality Data Integrity Authentication Non-repudiation Algorithmic Paradigm These paradigms have been the traditional frameworks for security on conventional networks, but what can we do differently for wireless systems?

Reevaluating the Security Paradigm, pg. 2 Confidentiality AvailabilityIntegrity Non Repudiation Intrusion Detection Privacy Resource Management Location Services We still need traditional security methods. But the wireless world has additional problems and new modalities for solutions! Wireless is easy to sniff. We still need encryption services and key management. Key freshness is an issue. The value of a wireless network is its promise of ubiquitous availability. Wireless networks are easy to break! Wireless resources (e.g. power and spectrum) must be managed. Greedy user behavior will cause resource management to malfunction. Perpetual connectivity can mean constant surveillance! With snooping one can monitor mobility and handoffs between networks. The pervasiveness of the wireless networks should not mean that just anyone can participate! Example: Rogue APs RF energy radiates, and wireless entities within the radio coverage pattern may serve as witnesses for the actions of the transmitter. Wireless hardware/equipment need to be safe from modification. Data/control info should not be modified before or during transit. Location is a new form of information provided by wireless systems that will facilitate new services. Location information needs to be trusted.

Drill Down: Specific Challenges and Some Strategies

Availability Attack: Radio Interference Bob Alice Hello … Hi … … Mr. X Alice and Bob are attacked by malicious Mr. X. A story for the problem of wireless denial of service attack we focus on. –Alice and Bob  two communicating nodes, A and B. –Mr. X  an adversarial interferer X. –Mr. X ’ s insane behavior  the jamming style DoS. –People and nodes in wireless network both communicate via shared medium. Jamming style DoS Attack: –Behavior that prevents other nodes from using the channel to communicate by occupying the channel that they are communicating on

Availability: Jamming Detection/Defense Detection: –Challenge is to discriminate between legitimate causes of poor connectivity and jamming Motivation from “The Art of War” by Sun Tze: –“He who cannot defeat his enemy should retreat.” Defense Strategies: –Spectral Evasion (Channel Surfing) –Spatial Evasion Latency and synchronicity is an issue as you move to many node networks! SDRs will allow more advanced forms of spectral evasion. Jammed Region PDR % PDR VS. SS SS(dBm) Trial Number (Time) Channel Surfing Experiment Packet Delivery Rate Jammer turned on Change channel

Intrusion Detection: Wireless Spoofing Many wireless security threats are possible because it is easy to spoof legitimate devices (ioctl/ipconfig) Example –Attacker armed with a laptop having 2 wireless cards. –One card monitors all TCP traffic on the AP channel –Second card sends back TCP replies to select TCP requests (e.g. all requests for a particular web page). These are sent as if appearing from the server the user was connecting to. –At the MAC layer the attacker spoofs AP by injecting custom x frames with AP’s source MAC address. Results: –The user session is hijacked. –Requested service is DoSed. –Easy to launch flooding DoS attacks at higher-layer buffers Internet MAC: x.y.z.w Late!

Intrusion Detection : Spoofing Defense Spoofing can be addressed through authentication services –Traditional authentication services employ cryptographic solutions (e.g. MACs, signatures) –Light-weight alternatives can reduce the load on buffers into cryptographic functions A lesson learned from : – has several fields controlled by firmware, which are hard for an attacker to bypass –The 12bit sequence # field is increased monotonically by 1 for each packet –Monotonicity provides a rule whose violation is easy to detect The sequence number was not intended to be a security field, but it can be! We may introduce filters that check monotonic conditions (or more generic rules)

Wireless Localization Security Location information will facilitate new computing services –Location-based file access control Problem: Localization methods are not secure! Traditional cryptography and network security can address cryptographic attacks (Is this beacon really from the AP?) Localization algorithms depend on measurements that are susceptible to attack!! Is cryptography alone enough? No!

Attacks on Signal Strength Distance is measured using the relationship between received signal strength and distance Adversary may affect the receive signal power by: –Alter transmit power of nodes –Remove direct path by introducing obstacles –Introduce absorbing or attenuating material –Introduce ambient channel noise Distance Power Received d1d1 r1r1 Absorbing Material r2r2 d2d2

Defenses for Wireless Localization Don’t rely entirely on traditional security! Two-tier approach to defending wireless localization… Add Security and Robustness! SECURITYSECURITY ALGORITHMALGORITHM Attacks ROBUSTALGROBUSTALG Add Authentication, Entity Verification, Etc…

Questions ?