"Applications of Operation Research"
SECURITY ISSUES IN AD HOC WIRELESS SENSOR NETWORKS OUTLINE • Introduction • Applications • Basic Operation • Security Issues • Research Projects INTRODUCTION • Ad Hoc Wireless Sensor Networks (WSNs) also called Wireless Sensor Networks • WSNs are composed of – A set of autonomous sensor nodes – Which form a distributed network – Using radio frequency transmissions INTRODUCTION • WSNs consist of small nodes called “motes” which can: – Communicate wirelessly with other motes – Contain one or more sensors – Route data to/through each other For example, a mote might contain sensors for: - Humidity - Temperature - Ambient light - Location (GPS) - Acceleration - Battery life INTRODUCTION • The motes connect to each other in an ad hoc fashion (i.e., the network designs itself for a specific task) • Connection is based on proximity and signal strength • The network configures (and reconfigures) using mesh networking routing protocols INTRODUCTION Internet Wireless Mote Wireless Mote Intranet Base Station Wireless Mote Wireless Workstation Mote Wireless Mote Wired Network Infrastructure APPLICATIONS WSNs have the potential for transforming communications in large-scale workplaces. They can provide: – Ease of deployment – Dynamic network configuration – Swift exchange of information – Real-time access to data APPLICATIONS Sniper Fire Medical Location Supervision Lighting Agricultural Control Monitoring Package / Mine / Inventory Tracking Surveillance Monitoring APPLICATIONS • Consider using WSNs in shipping containers Containers travel via trucks, trains and ships and often sit in storage on the docks What if a WSN mote is placed in each container? APPLICATIONS Many different topologies Trucks = 1-2 node WSNs Trains = multi-node WSNs Monitored at a central location Ships = multi-node WSNs Terminals = multi-node WSNs BASIC WSN OPERATION Ad Hoc WSN Test Bed BASIC WSN OPERATION Ad Hoc WSN Test Bed Technical Details • Implemented using Crossbow Products (now MEMSIC) • Half-duplex radios with 30-1000 feet range • Frequency bands: 2.4 GHz (433 MHz and 868-915 MHz also) • Low data rates of 19.2kbps - 240kbps • Battery life of up to 5 years in commercial applications • IEEE 802.15.4 / ZigBee protocol • XMesh (MEMSIC proprietary) ad-hoc, mesh networking protocol BASIC WSN OPERATION Graphical output showing a WSN self- configuring into a star topology BASIC WSN OPERATION Graphical output showing a WSN self- configuring into a linear topology BASIC WSN OPERATION Graphical output showing a mesh topology WSN with ambient light readings being reported by each mote BASIC WSN OPERATION Graphical output showing a mesh topology WSN with humidity readings being reported by each mote BASIC WSN OPERATION Graphical output showing a WSN with battery voltage levels being reported by each mote Battery life is a critical issue in WSN security WSN SECURITY ISSUES • WSNs currently have very weak security mechanisms • As with other types of network security, WSN security should provide data: – Confidentiality – Integrity – Authentication – Availability WSN SECURITY ISSUES WSNs have certain characteristics that make security difficult: • WSN motes have limited processing capability and memory. – Thus, computation-intensive, public-key cryptography is typically not used. • Wireless transmission leaves WSNs vulnerable. – Traffic eavesdropping and data leakage can occur. – Spurious data can also be injected into the network. • WSNs are often deployed in unsecured, publicly accessible areas. – Physical tampering and/or the destruction of motes can occur. • WSN motes are usually powered by batteries. – Energy conservation is critical. – Security attacks that target energy consumption can be performed. WSN SECURITY ISSUES WSN SECURITY ISSUES Examine security issues at each of the five TCP/IP protocol layers WSN SECURITY ISSUES Preliminary research shows WSN security vulnerabilities at every layer of the TCP/IP protocol stack. WSN SECURITY ISSUES Countermeasures for these attacks are in the early stages of development. Many WSN security issues need to be solved before they can be widely adopted. RESEARCH PROJECTS Focus on three security threats and countermeasures: Collision Attacks Selective Forwarding Attacks Desynchronization Attacks RESEARCH PROJECT 1 Collision Attacks and Error Correcting Codes @ Layer 2: Targeting Data Frames ATTACK: An attacker identifies the radio frequency of the WSN and sends traffic that interferes with the data frame being transmitted. A data collision occurs. RESULT: An error detecting code (like CRC) is used to identify the incorrect frames which are then discarded. COUNTERMEASURE: Error correcting codes are used instead of the standard error detecting codes. Additional redundant data is sent with each frame to allow the receiver to both identify the error and correct it. RESEARCH PROJECT 2 Selective Forwarding Attacks and Explicit Acknowledgements (ACKs) + Multipath Routing @ Layer 3: Targeting Routing Protocols ATTACK: An attacker inserts a mote into the network to join the routing process. The malicious mote then drops packets instead of forwarding them. RESULT: Data is lost. COUNTERMEASURES: Two promising countermeasures exist: (a) explicit ACKs can be used to ensure that each individual packet is forwarded as expected; (b) multipath routing can be used to increase the probability of reception. An RESEARCH PROJECT 3 Desynchronization Attacks and Authentication @ Layer 4: Targeting Transport Protocols ATTACK: An attacker transmits forged packets with incorrect sequence numbers into the network. RESULT: Incorrect sequence numbers force retransmission of packets and wastes both bandwidth and energy. COUNTERMEASURE: Authentication techniques (using encryption) can be applied to the packet header or entire packet preventing forged packets. RESEARCH METHODOLOGY • Implementation and performance measurement using the WSN Test Bed in NetLab. • Modeling and discrete event simulation of the WSNs. QUESTIONS?