Wireless Security CSE497b - Spring 2007 Introduction Computer and - PowerPoint PPT Presentation

Wireless Security CSE497b - Spring 2007 Introduction Computer and Network Security Professor Jaeger www.cse.psu.edu/~tjaeger/cse497b-s07/ CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger

At the mall ... 2 CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger Page Page

Wireless Networks • Network supported by radio communications .. • Alphabet soup of standards, most on 802.11 • .. destroys the illusion of a hard perimeter. 3 CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger Page Page

Why you should fear Simon Byers ... • 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. 4 CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger Page Page

Wireless LANs • 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. 5 CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger Page Page

Ad hoc Networks (a.k.a peer-to-peer) • 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 6 CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger Page Page

Devices • Laptops (canonical wireless devices) • Desktops, mobile phones, .... • Bluetooth 7 CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger Page Page

Attacks on Wireless Networks • DOS • Planted devices • Hijacked connections • Eavesdropping • Somebody is "in the wire" ... 8 CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger Page Page

Threats • This is an open network ... • ... to which anyone can connect. • What security is necessary? – Authentication? – Confidentiality? – Integrity? – Privacy? – DOS Protection? – Accountability (traceability)? 9 CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger Page Page

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 CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger Page

Wireless Security Approaches • MAC Authentication • WEP (Wired Equivalent Privacy) • 802.11i (WPA - Wifi Protected Access) • EAP/LEAP (Extensible Authentication Protocol) • WAP (Wireless Application Protocol) 11 CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger Page

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 CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger Page

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 CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger Page

The WEP Flaw (greatly simplified) Protocol • Passphrase Key k p • Initialization vector iv i • Plaintext data d 1 , d 2 (for separate blocks 1 and 2) • Traf fi c Key k ti = k p || iv i • Ciphertext = E ( k ti , d i ) = RC 4( k ti ) ⊕ d i Attack • Assume iv 1 = iv 2 • Only 17 million IVs ( 2 24 ), so IV of two packets can be found ( ≈ one in 4096) ( RC 4( k t 1 ) ⊕ d 1 ) ⊕ ( RC 4( k t 1 ) ⊕ d 2 ) = d 1 ⊕ d 2 Page 14 CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger Page

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 -- T emporal K ey I ntegrity P rotocol – improved integrity (stop using CRC and start using MAC) – WPA2: AES instead of RC4 Page 15 CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger Page

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 CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger Page

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 CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger Page

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 CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger Page

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 CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger Page

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, ... CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger 20

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 CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger Page