Wireless Local Area Networking (WLAN) Security Assessment And Countermeasures

Transcription

1 Wireless Local Area Networking (WLAN) Security Assessment And Countermeasures (IEEE Wireless Networks) James Burrell Research project submission for the partial fulfillment of the requirements for the degree of Master of Science in Telecommunications Advisor Dr. Jeremy Allnutt Director, M.S. Telecom Program George Mason University School of Information Technology & Engineering December 2002

2 Introduction To WLAN Technology

3 Introduction Wireless networking technologies offers many advantages over traditional wired (or physical) network connectivity, to include:!mobility support!rapid deployment of network resources!flexible implementation!scalability

4 Basic WLAN Components Wireless Network Interface Card (PCMCIA) Wireless Access Point

5 WLAN Spectrum Allocation

6 WLAN Spectrum Allocation ISM FREQUNCY BANDS Frequency (Lower Limit) Frequency (Upper Limit) Total Bandwidth 902 MHz 928 MHz 26 MHz 2.4 GHz GHz 83.5 MHz GHz GHz 125 MHz Industrial, Scientific, and Medical (ISM) Frequency Allocations (Source: Bruce)

7 WLAN Standards

8 WLAN Standards b HomeRF IrDA a g Bluetooth Max Speed 11Mbps 10Mbps 4Mbps 54Mbps 54Mbps 1 Mbps Frequency 2.4GHz 2.4 GHz Light waves 5GHz 2.4GHz 2.4 GHz Indoor Range feet 150 feet 1 meter feet feet 30 feet Applicatio n WLAN WLAN Device Beaming WLAN WLAN Personal Area Network Wireless Networking Standards and Specifications (Source: Anderson)

9 WLAN Transmission Technologies

10 WLAN Transmission Technologies Spread Spectrum Narrowbeam Microwave Infrared

11 Comparison of WLAN Transmission Technologies Transmission Technology Range Limitation Signal Interception Susceptibility Susceptibility To Interference / Jamming Low High Low High Low High Spread Spectrum **** **** **** Narrowband Microwave **** ******************** ******************** Infrared ****************** * **** ********************

12 WLAN Network Topologies

13 WLAN Topologies Laptop PDA Wireless Segment Ethernet Segment Peer-to-Peer (Ad hoc) Topology Hybrid Topology Laptop PDA Wireless Bridge Wireless Bridge Infrastructure Topology Point-to-Point Topology

14 IEEE Hybrid WLAN Topology Physical Network Segment LAN Switch Internet Router Network Firewall Laptop PDA Wireless Access Point Wireless Network Segment

15 WLAN Applications

16 WLAN Applications WLAN Topology Application Peer-to-Peer Ad hoc networking between mobile devices Hybrid (Wireless/Wired) Network extension for wired LAN infrastructure WLAN Client location flexibility and mobility Point-to-Point Wireless connectivity between buildings or facilities

17 WLAN Applications Organization Application Advantage Educational Institutions Classroom and student connectivity!relocation of devices to different locations in classrooms Health Care / Hospitals Patient monitoring and access to patient medical information!mobility Inventory Control Manufacturing Conference Centers Connectivity for portable inventory devices with central storage facility Network connectivity for machinery in open locations and hazardous environments Provide connectivity to attendees with enabled devices!real-time reporting!relocation of devices to different locations!hazardous environments!rapid deployment Education Shared computer resources among student classrooms and laboratories!mobility

18 WLAN Applications Tactical/Military Multimedia Resources Rapid establishment of network with mobility support in hazardous environments Provide wireless access to multimedia resources!mobility Rapid network deployment!shared Resources Small Office/Home Office (SOHO) Residential Rapid establishment of low cost network infrastructure Rapid establishment of low cost network infrastructure Low cost networking solution!low cost networking solution

19 WLAN Security Risks

20 WLAN Security Risks Network Detection RF Signal Limiting Interference and RF Disruption Unauthorized Network Access Denial of Service Insider Threat Compromised Devices Illicit Access Point Deployment Data Interception

21 WLAN Security Risks Security Vulnerability Relative Security Risk Level Low High Security Countermeasures Detecting WLANs RF Signal Propagation ******************** ******************** Deactivate access point beacon and advertisement transmission Minimize access point transmission level Interference and RF Disruption ******* Unauthorized Access ************************** Conduct RF environment analysis Strategic location of access point deployments Use strong authentication

22 WLAN Security Risks Data Interception **************************!Use encryption Denial of Service *************!Implement measures to secure against unauthorized access Insider Threat *********************!Background investigations!require change of encryption key upon employee termination/dismissal Compromised Devices *********************!Security awareness!reporting requirement for lost or stolen devices!require change of encryption key if compromise is suspected Illicit Access Point Deployment *********************!Limit physical access to wired network infrastructure!conduct routine monitoring for illicit/improperly configured access point

23 WEP Authentication / Encryption

24 WEP Encryption Process PLAINTEXT MESSAGE CRC Logical Exclusive-Or (XOR) Operation GENERATED ENCRYPTION SEQUENCE IV ENCRYPTED MESSAGE CRC IV LEGEND Cyclic Redundency Check Initialization Vector

25 Weaknesses of WEP Algorithm The primary issues that have led to the defeating the security provided by WEP, is related to the:!implementation of the encryption algorithm!relatively short length of the shared encryption key!iv being transmitted with its associated encrypted message!static nature associated with WEP encryption key management

26 WEP Encryption Process Initialization Vector (IV) Initialization Vector (IV) used to generate the used to generate the psuedo-random encryption psuedo-random encryption sequence is transmitted sequence is transmitted along with the encrypted along with the encrypted message message IV IV ENCRYPTED MESSAGE ENCRYPTED MESSAGE

27 RF Signal Limiting

28 SNR Measurements At Selected Distances (100mW Output Power) ' 20' 100'

29 SNR Measurements For Selected Output Power Levels SNR (db) mW 50mW 5mW 1mW Distance (Feet)

30 RF Interference Source Norma l Interference Source Figure X.X Microwave Interference Source Effect On WLAN Transmissions (Distance From Wireless Device 10 Feet)

31 Maximum Distances For Output Power Levels IEEE b 2.4 GHz Wireless Access Point Distance (Feet) Output Pow er (mw)

32 Firewall / Intrusion Detection System / VPN Integration

33 Firewall Integration Into A Wireless Network Segment Laptop PDA LAN Switch Firewall Wireless Access Point Wireless Network Segment

34 IDS Integration Into A Wireless Network Segment Intrusion Detection System Laptop PDA LAN Switch Firewall Wireless Access Point Wireless Network Segment

35 VPN Integration Into A Wireless Network Segment Laptop PDA LAN Switch VPN Gateway VPN / IPSec Tunnel Wireless Access Point Wireless Network Segment

36 Emerging Security Technology and Standards

37 Emerging Security Technology and Standards IEEE e - Quality of Service (QoS) IEEE g - 54 Mbps over 2.4 GHz band IEEE h Spectrum Manager a IEEE i - Enhanced security

38 Summary / Conclusion

39 Summary! The optimal security solution for WLANs involves a combination of security technologies! A detailed threat risk assessment and analysis is essential to determine which security measures, or combination of measures are the most effective! The implementation of preventive and protective end-toend security measures, such as firewalls, intrusion detection, and VPN technologies, provides the most secure and effective defense against the threats associated with the transmission of data over an insecure wireless medium

40 Summary! Requires implementation of policy requirements to ensure the effectiveness of security solutions! Training information will emphasize the importance of security to network users

41 Conclusion A combination of security measures will further increase the security offered by WLAN technologies Increased security will support new WLAN applications Emerging security technology will reduce the increasing security threats associated with providing wireless network connectivity