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CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger
Page CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger
At the mall ...
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Wireless Security CSE497b - Spring 2007 Introduction Computer and - - PowerPoint PPT Presentation
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
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Page CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger
Wireless Networks
- Network supported by
radio communications ..
- Alphabet soup of
standards, most on 802.11
- .. destroys the illusion of a
hard perimeter.
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Page CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger
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.
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Page CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger
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.
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Page CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger
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
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Page CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger
Devices
- Laptops (canonical wireless devices)
- Desktops, mobile phones, ....
- Bluetooth
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Page CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger
Attacks on Wireless Networks
- DOS
- Planted devices
- Hijacked connections
- Eavesdropping
- Somebody is "in the wire" ...
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Page CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger
Threats
- This is an open network ...
- ... to which anyone can connect.
- What security is necessary?
– Authentication? – Confidentiality? – Integrity? – Privacy? – DOS Protection? – Accountability (traceability)?
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Page CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger
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)
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Page CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger
Wireless Security Approaches
- MAC Authentication
- WEP (Wired Equivalent Privacy)
- 802.11i (WPA - Wifi Protected Access)
- EAP/LEAP (Extensible Authentication Protocol)
- WAP (Wireless Application Protocol)
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Page CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger
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
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ether 00:0a:95:d5:74:6a
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Page CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger
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
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Page CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger
The WEP Flaw (greatly simplified)
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Protocol
- Passphrase Key kp
- Initialization vector ivi
- Plaintext data d1, d2 (for separate blocks 1 and 2)
- Traffic Key kti = kp||ivi
- Ciphertext = E(kti, di) = RC4(kti) ⊕ di
Attack
- Assume iv1 = iv2
- Only 17 million IVs (224), so IV of two packets can be found (≈ one in 4096)
(RC4(kt1) ⊕ d1) ⊕ (RC4(kt1) ⊕ d2) = d1 ⊕ d2
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Page CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger
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
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Page CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger
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)
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Page CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger
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
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Page CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger
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?)
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Page CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger
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
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CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger
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, ...
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Page CSE497b Introduction to Computer and Network Security - Spring 2007 - Professor Jaeger
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 ...
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