WLAN SECURITY

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WLAN SECURITY

• TEAM NAME Crypto_5
• TEAM MEMBERS
• Rajini Ananthoj
• Srimani Reddy Gatla
• Ishleen Kour
• Pallavi Murudkar
• Deepagandhi Vadivelu

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Agenda

• WLAN and architecture
• Security issues faced in WLAN
• Basic security of WLAN
• solutions for WLAN security
• 802.1X
• EAP Authentication methods
• TKIP
• CCMP
• Intrusion prevention system
• Hardware solutions
• Things you can do to secure your wireless network
• Conclusion
• References

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WLAN and Architecture

• WLAN Linking of two or more computers without
  using wires which uses spread spectrum technology
  based on radio waves.

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Basic security in WLAN

• SSIDs, WEP, and MAC Address Authentication
• Service Set Identifiers Prevents access by any
  client device that does not have the SSID.
• Open or shared-key authentication, static WEP
  key Access point sends the client device a
  challenge-text packet which client must encrypt
• Media Access Control authentication clients MAC
  address matches an address in an authentication
  table

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Issues of WLAN Security

• Ad- hoc Networks
• Policy violation
• Identify theft
• Man in the middle attack
• Denial of service attack

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How WEP works
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WEP Issues

• Uses RC4, a synchronous stream cipher
• Does not provide mechanism for sharing Keys
• Changing the Initialization Vector (IV) with each
  packet is optional
• CRC-32 checksum used for message integrity is
  linear
• Concatenates IV directly to the Pre- shared key
  to produce a key for RC4

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What is wrong with 802.11 security

• Binds itself to cryptographic algorithm
• No security support for handshake
• Pre- shared keys
• One way authentication
• Wired equivalent privacy (WEP)

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Wi-Fi Protected Access (WPA)

• Interim interoperable standard created by Wi-fi
  alliance in response to weaknesses in Wired
  Equivalent Privacy (WEP)
• Intermediate measure to take the place of WEP
  while 802.11i was prepared
• Designed to work with all wireless network
  interface cards, but not all first generation
  wireless access points.
• Goals of WPA
• To address the issues with WEP encryption through
  a software upgrade
• To provide a secure wireless networking solution
  for small office/home office (SOHO) wireless
  users
• To be forward-compatible with the upcoming IEEE
  802.11i standard

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Features of WPA

• WPA Authentication
• Pre-shared key (PSK)
• every user given the same pass-phrase
• less secure
• preferred for Personal mode - homes, small
  offices
• IEEE 802.1X authentication
• server distributes different keys to each user
• enhanced security and authentication
• preferred for enterprise mode - business,
  government, education

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• Encryption
• RC4 stream cipher using 128-bit key, 48-bit IV
• larger IV defeats Key recovery attack
• Key Management
• Temporal Key Integrity Protocol (TKIP) -
  dynamically changes encryption keys for each
  packet.
• Payload Integrity
• 8 Byte Message integrity code( MIC)
• Calculated by algorithm called Michael
• Between the payload of the 802.11 frame and the
  4-byte ICV
• MIC includes a frame counter to prevent replay
  attacks

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• Thus, WPA makes breaking into a Wireless LAN
  difficult by
• Increasing the size of the keys and IVs
• Reducing the number of packets sent with related
  keys
• Adding a secure message verification system

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IEEE 802.11i / WPA2

• An amendment to the 802.11, specifying security
  mechanisms for wireless networks
• The draft standard was ratified on 24 June 2004
• adds stronger encryption, authentication, and key
  management strategies
• makes use of the Advanced Encryption Standard
  (AES) block cipher instead of RC4 stream cipher.
• the use of WPA2 needs firmware or driver support
  of the wireless host (router or access point) and
  the wireless client (adapter).

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Components of WPA2

• 802.1X Port-Based Network Access Control for
  authentication
• Counter Mode with CBC-MAC Protocol (CCMP) for
  confidentiality, integrity and origin
  authentication
• Temporary Key Integrity Protocol (TKIP) (check)
• 4-Way Handshake for Encryption key distribution
  

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Comparisons between WPA and WPA2 modes
WPA WPA2
Enterprise Mode (Business, Government, Education) Authentication IEEE 802.1X/EAP Encryption TKIP/MIC Authentication IEEE 802.1X/EAP Encryption AES-CCMP
Personal Mode (SOHO, Home/Personal) Authentication PSK Encryption TKIP/MIC Authentication PSK Encryption AES-CCMP
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IEEE 802.1X

• 802.1X is an IEEE standard for port-based Network
  Access Control for LANs
• For WLANs, it is based on the EAP, Extensible
  Authentication Protocol
• Fullfills the security loopholes of access
  control, authentication and key management in
  802.11 architecture
• Contributes to a solution RSN
• The authentication is usually done by a
  third-party entity, such as a RADIUS server

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802.1X Authentication and Access Control

• Client -Supplicant
• Access point -Authenticator

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• Authenticator deals with controlled and
  uncontrolled ports

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• 802.1X Key Management Broadcast Key Rotation
  (BKR)
• AP periodically broadcasts the WEP shared / root
  key
• Mobiles creates session encryption keys by
  combining the IV with the broadcast root key
• Larger key space key-hopping cycles through IV
  space as well as the session key set
• Message Integrity
• A non-linear MIC prevents bit-flip attacks on
  encrypted packets.
• Implemented on access point and client devices
• Adds a few bytes to each packet to make the
  packets tamper-proof

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EAP AUTHENTICATION METHODS

• EAP-MD5 Requires username/password , does not
  provide dictionary attack resistance, mutual
  authentication, or key derivation
• Lightweight EAP (LEAP) A username/password
  combination is sent to a Authentication Server
  (RADIUS) for authentication.
• EAP-TLS Creates a TLS session within EAP,
  between the Supplicant and the Authentication
  Server. Both the server and the client(s) need a
  valid (x509) certificate, and therefore a PKI.
  This method provides authentication both ways.
• EAP-TTLS Sets up a encrypted TLS-tunnel for safe
  transport of authentication data. Within the TLS
  tunnel, (any) other authentication methods may be
  used.
• Protected EAP (PEAP) Uses, as EAP-TTLS, an
  encrypted TLS-tunnel. Supplicant certificates for
  both EAP-TTLS and EAP-PEAP are optional, but
  server (AS) certificates are required
• EAP-MSCHAPv2 Requires username/password, and is
  basically an EAP encapsulation of MS-CHAP-v2
  .Usually used inside of a PEAP-encrypted tunnel

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TKIP - Temporal Key Integrity Protocol

• RC4 stream cipher as in WEP
• Keys used for encryption - 128-bit long
• Keys used for authentication - 64 bit long
• TKIP provides
• Per-Packet Key Hashing to Mitigate "Weak IV"
  Attacks Each time a wireless station associates
  to an access point, a new base key is created
  which is built by hashing base key with the IV.
• Prevention of Collision attacks Each packet
  transmitted using TKIP has a unique 48-bit serial
  number which incremented every time a packet is
  transmitted. This solves another problem in WEP,
  called "collision attacks," which can occur when
  the same key is used for two different packets.

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CCMP (Counter Mode with CBC MAC Protocol)

• CCMP uses the counter mode (CTR) for data
  confidentiality and the Cipher Block Chaining
  Message Authentication Code (CBC-MAC) for data
  integrity.
• It uses the Advanced Encryption Standard (AES)
  algorithm with a 128-bit key and a 128-bit block
  size.
• CCMP provides MIC protection over both the frame
  body and nearly the entire header in a MAC frame,
  which prevents an adversary from exploiting the
  MAC headers.
• CCMP uses a 48-bit Packet Number (PN) to prevent
  replay attacks and construct a fresh nonce for
  each packet
• Analysis suggests that once CCMP is implemented,
  an adversary will not able to break the data
  confidentiality and integrity without the
  knowledge of the key.

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Dynamic Key Exchange and Management

• 802.11i - key derivation/management regime

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IPS - Intrusion Prevention System

• An intrusion prevention system is a computer
  security device that exercises access control to
  protect computers from exploitation.
• IPS make access control decisions based on
  application content, rather than IP address or
  ports as traditional firewalls.
• Access points acts as air monitors and data
  forwarding devices which allows access points to
  communicate real-time information about the
  wireless domain, including potential security
  threats to Wireless LAN controllers

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Cisco Unified IDS/IPS

• The Cisco Unified IDS/IPS is part of the Cisco
  Self-Defending Network and is the industry's
  first integrated wireline and wireless security
  solution.
• When an associated client sends malicious traffic
  through the Unified Wireless network, the Cisco
  wireline IDS device detects the attack and sends
  shun requests to Unified WLAN controllers which
  will then disassociate the client device

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Some other solutions

• Smart cards
• Beneficial in environments requiring
  authentication beyond simple username and
  password
• User certificate and other information are stored
  on the cards
• Portable - users can securely access their
  networks from various locations
• VPN
• Provides secure data transmission across public
  network infrastructures.
• VPNs employ cryptographic techniques to protect
  IP information as it passes from one network to
  the next .
• Use IPsec Protocol suite for ensuring private
  communications.
• Biometrics
• For agencies needing higher levels of security,
  biometrics such as fingerprint/palm-print
  scanners , optical scanner can be integrated with
  wireless smart cards

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Things you can do to secure your wireless network.

• Change the default Admin password on your Access
  Point
• Check / Update the firmware for your Wireless
  Access Point and drivers for your Wireless
  Adapter.
• Use the highest level of WEP/WPA (WPA2/802.11i
  strongly preferred) -- Use decent keys.
• Authenticate wireless users with protocols like
  802.1X, RADIUS, EAP (including EAP-PAX, EAP-PSK,
  EAP-TLS, EAP-TTLS, PEAP, and EAP-SIM).
• Use strong encryption for all applications you
  use over the wireless network, e.g., use SSH and
  TLS/HTTPS.
• Encrypt wireless traffic using a VPN (Virtual
  Private Network), e.g. using IPSEC or other VPN
  solutions.

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Conclusion

• The optimal security solution for WLAN 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.

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References

• en.wikipedia.org/wiki/Wi-Fi_Protected_Access
• en.wikipedia.org/wiki/WPA2
• http//en.wikipedia.org/wiki/IEEE_802.1x
• en.wikipedia.org/wiki/TKIP
• http//www.networkworld.com/reviews/2004/1004wirel
  esstkip.html
• http//tldp.org/HOWTO/html_single/8021X-HOWTO/p80
  21x
• www.wi-fiplanet.com/tutorials/article.php/953561
• www.drizzle.com/aboba/IEEE/