Wireless Security. CSE497b - Spring 2007 Introduction Computer and Network Security Professor Jaeger.

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1 Wireless Security CSE497b - Spring 2007 Introduction Computer and Network Security Professor Jaeger

2 At the mall... Page 2

3 Wireless Networks Page 3 Network supported by radio communications.. Alphabet soup of standards, most on destroys the illusion of a hard perimeter.

4 Why you should fear Simon Byers... Page 4 Over the course of history radio frequencies have been enormously vulnerable to eavesdropping and manipulation. ASSUME: Everything you say on a wireless network is going to be heard and potentially manipulated by your adversaries.

5 Wireless LANs Page 5 Access point networks (ranging to about 300 feet) All devices connect to the central access point Pro: very easy to setup and maintain, simple protocols Con: reliability/speed drops as you get away from AP or contention increases.

6 Ad hoc Networks (a.k.a peer-to-peer) Page 6 Devices collaboratively work together to support network communication Network topology changes in response to moving devices, e.g., bluetooth Pro: highly flexible and responsive to changes in environment Con: complex, subject to traffic manipulation by malicious peers

7 Devices Page 7 Laptops (canonical wireless devices) Desktops, mobile phones,... Bluetooth

8 Attacks on Wireless Networks DOS Planted devices Hijacked connections Eavesdropping Somebody is "in the wire"... Page 8

9 Threats This is an open network to which anyone can connect. What security is necessary? Authentication? Confidentiality? Integrity? Privacy? DOS Protection? Accountability (traceability)? Page 9

10 Security Mechanisms Note: this is just a network with different threats, so implementing security is very similar to network security Authentication Q: What are you authenticating in a wireless network? Methods: password/passphrase, smartcard, etc. Tools: radius, Kerberos, PKI services... Confidentiality/Integrity Typically implemented via some transport protocol IPsec (just implement a VPN -- this is what PSU does) Page 10

11 Wireless Security Approaches MAC Authentication WEP (Wired Equivalent Privacy) i (WPA - Wifi Protected Access) EAP/LEAP (Extensible Authentication Protocol) WAP (Wireless Application Protocol) Page 11

12 MAC Authentication Create a list of MAC addresses media access layer, e.g., ether 00:0a:95:d5:74:6a Only these devices are allowed on network Attack Listen on network for MAC address use -- laptop Masquerade as that MAC address (easy to do, many devices programmable)... can wait for it to go off line to avoid conflict, but not necessary ARP Security limitations ether 00:0a:95:d5:74:6a Page 12

13 WEP (Wired Equivalent Privacy) Keys Pass-phrase converts 40 bits from passphrase, plus 24 bit initialization vector (or) 26 char hexadecimal + 24-bit IV = 128-bit WEP Ability to send packets is essentially authentication integrity used as authentication Built into the vast majority of home wireless routers Page 13

14 Page 14 y k p The WEP Flaw (greatly simplified) ector iv i d 1, d 2 (for separate blocks 1 and 2) Protocol i = k p iv i Passphrase Key k p Initialization vector iv i (k ti, d i ) = RC4(k ti ) d i Plaintext data d 1, d 2 (for separate blocks 1 and 2) Traffic Key k ti = k p iv i Ciphertext = E(k ti, d i ) = RC4(k ti ) d i iv 2 Attack Assume iv 1 = iv 2 Only 17 million IVs (2 24 ), so IV of two packets can be ( one in 4096) n IVs (2 24 ), so IV of two packets can be found ( one in 4096) (RC4(k t1 ) d 1 ) (RC4(k t1 ) d 2 ) = d 1 d 2 (RC4(k t1 ) d 1 ) (RC4(k t1 ) d 2 ) = d 1 d 2

15 802.11i (WPA - Wifi Protected Access) Solution to problems with WEP Two modes of operation Pre-shared key mode -- WEP like, shared key derived from single network passphrase Server mode -- uses 802.1X authentication server to authenticate/give unique keys to users Protocol fixes to WEP increase IV size to 48 bits TKIP - change keys every so often -- Temporal Key Integrity Protocol improved integrity (stop using CRC and start using MAC) WPA2: AES instead of RC4 Page 15

16 WAP (Wireless Application Protocol) A set of protocols for implementing applications over thin (read wireless) pipes. Short version: a set of protocols to implement the web over wireless links as delivered to resource limited devices reduce overhead and flabby content (image rich HTML) support limited presentation and content formats Wireless Markup Language (XML-based language) reduce the footprint of the rendering engine (browser) Security: WTLS SSL/TLS protocol -- public keys, key negotiation, etc. Success in Japan, little elsewhere (currently) Page 16

17 EAP/LEAP Extensible Authentication Protocol Challenge response - auth. only Bolts onto other authentication mechanisms, e.g., Kerberos, RADIUS Passes authentication information onto other protocols (WEP, WAP) LEAP: Cisco implementation/modifications (security problems are possibly serious) Standards: EAP-MD5, EAP-TLS PEAP: RSA/Microsoft/Cisco standards for WPA/WPA2 protocols Page 17

18 Bluetooth A standard for building very small personal area networks (PANs) Connects just everything you can name: PDAs, phones, keyboards, mice, your car Very short range range network: 1 meter, 10 meters, 100 meters (rare) Advertised as solution to "too many cables" Authentication "pairing" uses pass-phrase style authentication to establish relationship which is often stored indefinitely (problem?) Page 18

19 Bluetooth Security Everything really works off the PIN Attacks have progressively been successful at identifying vulnerabilities in the way PINs are used, can be reverse engineered Privacy: know what is on and how public it is... Problem: Cambridgeshire, England Problem: Bluetooth rifle Page 19

20 RFIDs Radio Frequency Identification (RFID) identity-providing transponders Passive: no external power - backscatter (Walmart) Active: internal power (SpeedPass) History: a soviet listening device (1945), alied FoF (1939) Privacy/Security anyone? Q: How do you control who is accessing your information? A: You don t (currently) Security measures Rolling code (one time tokens) Crypto-protocols, limited range,... 20

21 NIST Evaluation Any vulnerability in a wired network is present in the wireless network Many new ones: protocols, systems more public and vulnerable Recommendations: Disable file and directory sharing Turn off APs when not in use Use robust passwords, 128-bit encryption Audit, audit, audit VPNs are a good... Page 21

12/3/08. Security in Wireless LANs and Mobile Networks. Wireless Magnifies Exposure Vulnerability. Mobility Makes it Difficult to Establish Trust

12/3/08. Security in Wireless LANs and Mobile Networks. Wireless Magnifies Exposure Vulnerability. Mobility Makes it Difficult to Establish Trust Security in Wireless LANs and Mobile Networks Wireless Magnifies Exposure Vulnerability Information going across the wireless link is exposed to anyone within radio range RF may extend beyond a room or