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ISSA Senforce Wi-Fi Workshop

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					Best Practices for Wi-Fi Security

         Lansing ISSA
        March 30th 2006


             Dr Tim Cranny
       Senforce Technologies, Inc.
Wi-Fi Technology Workshop Agenda


   Introduction
   Technology Overview
   The Threats
   The Solutions
   Best Practices for Securing Wi-Fi

   Roundtable Discussion
Overview of the Wireless World


                                If in the same
                                building, use Wi-Fi




                                                  Person 1
   HEAD OFFICE        BRANCH OFFICE
Overview of the Wireless World
                                      For your
                                      Personal Area Network,
                                      use Bluetooth




                                                 Person 1
   HEAD OFFICE        BRANCH OFFICE
Overview of the Wireless World

                 If in the same city, use WiMAX
                 for local connectivity




                                                  Person 1
   HEAD OFFICE             BRANCH OFFICE
Overview of the Wireless World




                                                 Person 1
   HEAD OFFICE        BRANCH OFFICE



                      For sensor networks and the like
                      use ZigBee
Overview of the Wireless World



                               ZigBee
                                             Bluetooth

                 WiMAX                   Wi-Fi




                                                         Person 1
   HEAD OFFICE           BRANCH OFFICE
IEEE 802 Working Groups

  •   802.1 Higher Layer LAN Protocols Working Group
  •   802.3 Ethernet Working Group
  •   802.11 Wireless LAN Working Group
  •   802.15 Wireless Personal Area Network (WPAN)
      Working Group
  •   802.16 Broadband Wireless Access Working Group
  •   802.17 Resilient Packet Ring Working Group
  •   802.18 Radio Regulatory TAG
  •   802.19 Coexistence TAG
  •   802.20 Mobile Broadband Wireless Access (MBWA)
      Working Group
  •   802.21 Media Independent Handoff Working Group
  •   802.22 Wireless Regional Area Networks
Overview of Wi-Fi Technologies

  • 802.11b
    – Wireless local-area network technology
    – Uses the 2.4 GHz spectrum (same as Bluetooth,
      microwave ovens, cordless phones, water’s resonant
      frequency, etc.)
    – 11 channels, 3 non-overlapping (channels 1, 6, and 11)
    – 802.11b’s data throughput rate is 1 to 11 Mbps using
      Direct Sequence Spread Spectrum (DSSS)
Little-known Fact #17:




    All wireless security specialists are remarkably attractiv
Overview of Wi-Fi Technologies

  • 802.11a
    – Wireless local-area network technology
    – Uses the 5 GHz spectrum
    – 12 Channels all of which are non-overlapping (only 8
      currently implemented)
    – Throughput of 1 to 54 Mbps (higher throughput when
      combining channels) using Orthogonal Frequency
      Division Multiplexing (OFDM)

  • 802.11g
    – Wireless local-area network technology
    – Uses the 2.4 GHz spectrum (same as Bluetooth,
      Microwave ovens, Cordless phones, water’s resonant
      frequency).
    – 11 Channels (3 non-overlapping (1, 6, 11))
    – 802.11g throughput is 1 to 54 Mbps (higher throughput
      when combining channels) using Orthogonal Frequency
      Division Multiplexing (OFDM)
Overview of Wi-Fi Technologies

  • 802.15 Personal Area Networks (PAN)
    – cable-free connecting of personal devices (phones, PDAs,
      ear-pieces, etc…)
    – solutions need to be low-power, low-range, low-cost
    – Bluetooth 2.4 GHz
       • Cable replacement technology
       • Primary application: wireless cell phone headset/microphone
    – Ultra Wide Band (UWB)
       •   3.1 to 10.6 GHz
       •   100 Mbs
       •   30 feet
       •   The technology is sound
       •   Difficult politics to overcome in 802.15
Overview of Wi-Fi Technologies

  • 802.16 – “WiMAX”
    –   Metropolitan Wireless Delivery
    –   Created as a competitor to DSL and Cable Modem
    –   10 and 66 GHz
    –   Continuously varying traffic levels at many licensed
        frequencies (e.g., 10.5, 25, 26, 31, 38 and 39 GHz) for
        two-way communications.
         • This enables interoperability among devices, so carriers
           can use products from multiple vendors.
    – Originally aimed at SMB and residential markets
Overview of Wi-Fi Technologies

  • 802.15.4 Wireless Personal-Area Network
    (WPAN) aka: Task Group 4
    – “Zigbee”
       • Sensor networks
          – Status and control
       • Low power
       • Low speeds
       • Extremely low cost
Overview of Wi-Fi Technologies

  These technologies:
    – Give workers new flexibility and convenience;
    – Change and improve business processes; and
    – Combine with new protocols like IPv6 to open up
      entirely new scenarios…



  But is there a downside…?
Wireless – the Security Issues

  Wireless introduces a number of significant security
  threats. These can be broadly categorized as:

        1. Threats to the network topology;

        2. Threats to communications confidentiality/integrity; and

        3. Management threats/issues.
How Wireless Should Work
Subversion of the Network Topology

  Failure Mode 1: „Promiscuous‟ internal APs


       hacker or
       passer-by
Subversion of the Network Topology

  Failure Mode 2: „Perimeter-crossing‟ ad-hoc networks


       hacker or
       passer-by
Subversion of the Network Topology

  Failure Mode 3a: Internal ad-hoc networks
Subversion of the Network Topology

  Failure Mode 3b: „Generic‟ ad-hoc networks




          Notebook                      Hacker
          at Starbucks
          or Airport departure lounge
          or ….
Subversion of the Network Topology

  Failure Mode 4: Accidental Associations


    External
    malicious or
    non-malicious
    Access Point
Subversion of the Network Topology

  Failure Mode 5: Internal Rogue APs
                                 I bought the
                                     AP at
                                 RadioShack!
Subversion of the Network Topology

  Failure Mode 6: Man-in-the-Middle Attacks

       What SEEMS to be happening….



     I‟m connected to
    the Internet in the
        usual way




                                              Internet




                          „Official‟
                          Access Point
Subversion of the Network Topology

  Failure Mode 6: Man-in-the-Middle Attacks

       What is REALLY happening…


                          External malicious Access Point,
                          posing as official AP
     I‟m connected to
    the Internet in the
        usual way




                                                             Internet




                           „Official‟
                           Access Point
Next Threat: Subversion of Communications

 Wireless communications are, by their nature,
 particularly vulnerable to certain threats, such as:

        1. passive interception of data (eavesdropping)

        2. active injection of malicious traffic
Subversion of Communications

  Failure Mode 7: Eavesdropping
Subversion of Communications

  Failure Mode 7: Eavesdropping
Subversion of Communications

  Failure Mode 8: Injection of Traffic




                           Typically not injection of data traffic,
                           but malicious management traffic
Other Wireless Issues

 Management Issues
   • Immature architectural patterns
   • Immature management systems
   • Wireless spans the infrastructure/endpoint divide


 Other Issues
    • Physical issues (eg RF management, layout)
    • Other deployment issues (default channel crowding, etc…)
What are the Solutions?
The Good News…

 Most of these problems are NOT fundamentally new,
 and over the years, security experts have created
 solutions that can be re-used in this new context.

  The threats we highlighted can be described as:
     • configuration problems
     • authentication problems
     • communication integrity/confidentiality problems
Overview of Wi-Fi Security History




    The first (attempted) solution was Wired Equivalent Privacy,
    or „WEP‟, which was part of the standard on day one.

    It was intended to address the threats to
    communications integrity and confidentiality.
Overview of Wi-Fi Security History

 WEP Features:

 • Shared Key Authentication
   – Client requests SK Authentication to the AP.
   – Access Point (AP) sends challenge text in clear to the client
   – Client encrypts the challenge text and sends it back to the
     AP for validation. (consequently, sniffers can see clear and
     encrypted text during the same session, exposing simple
     “reversal” of the key)
   – Upon validation the Client is “Authenticated” and
     “Associated” to the AP.
 • Open Authentication
   – Originally proposed due to “man-in-the-middle” weakness
     of SK.
   – Client requests Authentication to AP.
   – AP accepts (unless load balancing and/or MAC filtering fails)
   – NO static key validation is done (Wi-Fi adapter and AP both
     assume that 1 of the 4 key indexes available match)
Overview of Wi-Fi Security History
• “Key” WEP Weaknesses
   – Static Keys (generally manually disseminated to
     endpoints).
   – Several “weak initialization vectors (IVs)” used
      • Duplicate and/or static, short IVs are used
      • RC4 based encryption is susceptible to Scott Fluhrer, Itsik
        Mantin, and Adi Shamir (FSM) RC4 key scheduler attack
   – 40 bit key (24 bit IV) can be compromised with either
     “Brute Force” (few hours) or FSM attacks (~100 MB of
     data provided weak IVs are used)
   – 104 bit key (24 bit IV) also prone to BF and FSM
     attacks (time/data required scales linearly to 40bit
     WEP)
   – Unicast and multicast/broadcast traffic both use the
     same keys for encryption (the client and AP can use a
     different key index that each other)
   – Some weaknesses are mitigated by 802.1X integration
     (dynamic, individual keying with 128 bit keys)
Overview of Wi-Fi Security History

  WEP needed to be replaced with a
  comprehensive solution that combined:
     – strong authentication technologies; and,
     – strong encryption technologies.


  These two solutions were respectively:
  802.1x      and    802.11i
Overview of Wi-Fi Security History

  802.1x and       802.11i
     – taking too long;
     – surrounded by technical challenges.




  “They didn’t want it great, they wanted it Thursday.”
                                 - Ronald Reagan.


  The interim solution:   Wi-Fi Protected Access (WPA).
Overview of Wi-Fi Security: WPA

  • Wi-Fi Protected Access (WPA)
  • Uses Temporal Key Integrity Protocol (TKIP) for data
    Encryption
     –   Still RC4 based
     –   Per packet key mixing function
     –   Message Integrity Check (MIC)
     –   Longer IVs (48 bit versus 24 for WEP) with sequencing rules
     –   Re-keying mechanism
  • Uses a set of four different keys for each wireless client-
    wireless AP pair (known as the pairwise temporal keys) and a
    set of two different keys for multicast and broadcast traffic
  • Backwards compatible with existing Wi-Fi adapters and Access
    Points (these means the AP can be setup to accommodate both
    TKIP and WEP clients which means multicast traffic uses WEP
    and unicast traffic matches the clients encryption method).
  • Pre-Shared Key (PSK), or WPA personal, uses a static “seed”
    key shared between the AP and Client (subsequent per packet
    and re-keying keys are then derived and used for data
    encryption)
  • Integrates with EAP (802.1x) for session based “seed” key
  • Only has 128 bit key encryption
Overview of Wi-Fi Security: 802.1x, 802.11i

• Why 802.1x?
  – Provides a framework for wireless security
       • Authentication
       • Establishment of keys for encryption
   – Uses Extensible Authentication Protocol (EAP) between client and
     access point for secure credential exchange
   – Uses EAP in RADIUS for authentication against back-end data stores
   – Creates Session Based Keys for each user logged in (this can also be
     configured to various re-keying intervals)
• Why RADIUS?
   – Authentication is user-based, not device-based
   – Centralizes management of user security information
   – Already widely deployed
• Why EAP?
   – New protocols can be added without modifying access points
   – Several strong protocols have already been developed
Overview of Wi-Fi Security: 802.1x, 802.11i

 How 802.1x Works
        CLIENT                      AP                            RADIUS




                     802.1x
                    request
                                           “Client wants to
                                           access network”

                                         “Allowed / disallowed”
                     802.1x
                 allow / disallow
                                              key material
                  key material
Overview of Wi-Fi Security: 802.1x, 802.11i

 802.11i

 • One implementation is ‘WPA2’
 • Uses Advanced Encryption Standard (AES) and
   Counter Mode with Cipher Block Chaining
   Message Authentication Code Protocol (CCMP)
   encryption
 • AES-CCMP is the government standard for data
   privacy (fulfills FIPS 140-2 requirement)
 • Re-keying mechanism
    – 128, 192, or 256 bit keys
    – Not backwards compatible with existing Wi-Fi adapters and
      APs (primarily due to overhead of encryption and larger key
      sizes)
Wi-Fi Security Comparison Matrix


       ENCRYPTION                         ENCRYPTION
                           KEY SIZE         METHOD
                                                                    VULNERABILITIES
        PROTOCOL

                                                       No message integrity code makes it open to
  Wired Equivalency        40, 128-
                                        RC-4           packet injection and replay attacks, weak
  Protocol (WEP)           bit
                                                       initialization vectors


                           40, 128-                    Open to packet injection, weak initialization
  Dynamic WEP (802.1X)                  RC-4
                           bit                         vectors


  Temporal Key Integrity
                                                       Weak message integrity code, packet
  Protocol (TKIP) - WPA    128-bit      RC-4
                                                       injection
  1.0


                           128, 168,
  IPSEC                    192 or       3DES, AES
                           256-bit


  AES-CCMP - 802.11i
                           128, 192                    Message integrity code and encryption keys
  (Advanced Encryption                  AES
                           or 256-bit                  are identical
  Standard)
Now What Do We Do?


  In practice, these tools are only a small part
  of a comprehensive Wi-Fi security solution.

  What else should I be doing?

  What are „best practices?’
Best Practices in Wireless Security

  Need to address all the aforementioned threats:

     • for those „starting clean‟;

     • for those „starting small‟; and

     • those with legacy deployment issues.
Best Practices in Wireless Security

   We‟d divide this topic up into:

      • general strategies;

      • best practices for topology issues; and

      • best practices for communications issues.
General Security Strategies

  First Option:

  Buying time, or „keeping the genie in its bottle‟, by NOT
  deploying wireless…

  AND preventing it from being “virally deployed”!

  This requires mechanisms for:
      • disabling wireless on the endpoint (including
           after-market devices);
      • detecting wireless in the environment;
General Security Strategies

  Second Option:

  Allow wireless, but control every aspect of it from the start:

      • in the infrastructure

      • on the endpoint
Security Strategies: Topology Threats

  These threats were categorized as:

     • Promiscuous internal APs

     • Ad-hoc networking (multiple variants)

     • Accidental associations to external, non-authorized APs

     • Internal rogue APs

     • Man-in-the-Middle attacks
Security Strategies: Topology Threats

  Promiscuous internal APs:

  This is an Authentication issue, and is solved by
  proper configuration of the infrastructure devices.


  Partial answer: Filtering on IP and/or MAC addresses

  More complete answer: Tools such as RADIUS, 802.1x, etc…
Security Strategies: Topology Threats

 Ad-hoc networking (multiple variants):


 This will not be solved by infrastructure techniques, and needs
 the security administrator to impose controls on the endpoints.



 These controls should include:
    1. the ability to completely disable ad hoc networking by endpoints;
    2. the ability to impose centrally-controlled firewalls on the endpoints.
Security Strategies: Topology Threats

  Accidental associations to external, non-authorized APs:


  This should be solved by a combination of:
      1. infrastructure mechanisms to detect and/or block such APs;

      2. endpoint mechanisms to block the use of such APs
         (i.e. to white-list the authorized APs);
Security Strategies: Topology Threats

  The use of internal Rogue APs:


  This should be solved by a combination of:
      1. infrastructure mechanisms to detect and/or block such APs;

     2. endpoint mechanisms to block the use of such APs
        (i.e. to white-list the authorized APs);
Security Strategies: Topology Threats

  Man-in-the-Middle attacks:


  In most cases, there‟s essentially nothing you can do at the infrastructure
  level. You can, however:
      1. impose on the endpoint use of tighter authentication of APs; and
      2. deny the attacker any data from being „in the middle‟ via
           encryption controls imposed on the endpoint.
Security Strategies: Communication Threats

   These Threats were categorized as:

      • Eavesdropping;

      • Injection of malicious traffic;
Security Strategies: Communication Threats

  Eavesdropping:

  This is essentially a modest variation on a problem that
  goes back thousands of years. The primary answer is still
  ENCRYPTION.

     • 802.11i where possible (eg WPA2);
     • WPA where that is not possible;
     • WEP where that is not possible.

     • at a separate layer, VPN enforcement on the endpoint
       („whenever possible‟).
Security Strategies: Communication Threats

  Injection of malicious traffic:
     • same advice as on previous slide re encryption protocols;

     • standard hardening advice re the targeted hosts;

     • security-conscious selection of vendors;

     • network monitoring of traffic;

     • host monitoring of infrastructure.
Security Strategies: General Threats

 These ‘general threats’ were:

 Management Issues
   • immature architectural patterns;
   • immature management systems;
   • wireless spans the infrastructure/endpoint divide;

 Other Issues
    • physical issues (eg RF management, layout);
    • other deployment issues (default channel crowding, etc…)
Security Strategies: General Threats

 Unfortunately, these „general threats‟ can only be addressed
 through „general caution‟ and „general common sense‟:

    • minimize vendor lock-in on products;

    • minimize vendor lock-in on design patterns/architecture;

    • look for standards-based management systems;

    • be critically aware of the role of the endpoint;

    • look for deployment best practices.
Security Summary: What Do You Need?


                         Air Magnet
                                                     Senforce
                       A few vendors,
       On the         with many using Very few vendors,
      Endpoint               Air Defense
                    ‘fake infrastructure’ emerging space
                           instead.
                              Aruba               Cirond



                                                Cisco     Aruba
                           Air Magnet     Multiple vendors,
       On the                               with varying
                                                   Blue Socket
   Infrastructure                            breadth of
                                            features and
                            Air Defense
                                               maturity
                                               Sygate


                          Monitor               Enforce
                           only                 Security
                                                Policies
Security Summary: What To Ask Vendors

  To find the solutions you need for wireless security,
  the following can help cut through vendor hype:

  • Do you actively enforce wireless security
    measures, or do you just monitor/measure
    compliance?

  • If you enforce, do you do it on the endpoint, or
    just back in the infrastructure?

  • Which threats do you mitigate? Which threats do
    you not mitigate?

  • Can you dynamically select and enforce location-
    specific policies, or do you take a ‘one size fits
    all’ approach?
Roundtable Discussion

  • What are your experiences in the wireless
    world?

  • What scares you?

  • What are your current challenges?

  • What do you think your future challenges will
    be?

  • What are the ‘missing security solutions’?
Thank You!
Useful Information

  • Quick overview of IEEE 802
  • IEEE 802.11 Task Groups
Quick Overview of IEEE 802

  • 802.1 Higher Layer LAN Protocols Working
    Group
  • 802.3 Ethernet Working Group
  • 802.11 Wireless LAN Working Group
  • 802.15 Wireless Personal Area Network (WPAN)
    Working Group
  • 802.16 Broadband Wireless Access Working
    Group
  • 802.17 Resilient Packet Ring Working Group
  • 802.18 Radio Regulatory TAG
  • 802.19 Coexistence TAG
  • 802.20 Mobile Broadband Wireless Access
    (MBWA) Working Group
  • 802.21 Media Independent Handoff Working
    Group
  • 802.22 Wireless Regional Area Networks
IEEE 802.11 Task Groups

  •   11a UNII Band – 5.4 GHz
  •   11b 2.4 GHz
  •   11b Cor1 – MIB fix up
  •   11c Addendum to .1D for Bridging
  •   11d Other countries spectrum
  •   11e Quality of Service (QOS)
  •   11f Inter-Access Point Protocol (IAPP)
  •   11g Higher speeds in 2.4 GHz
  •   11h Enhancements to 11a PHY
  •   11i Security Enhancements
  •   11j Japanese specification
  •   11k Spectrum management
  •   11m Maintenance
  •   11n High Speed >100 Mbs
  •   11p Automobile to Road Side Sensors
  •   11r Real Time Traffic support
  •   11s Mesh Networking
  •   11t Performance Management
  •   11u Internetworking with other wireless technologies
  •   11v Wireless Management
Useful Internet Links

 • IEEE 802 web site www.ieee802.org
 • The unofficial 802.11 web site
   http://www.drizzle.com/~aboba/IEEE/
 • Get 802 – Free electronic copies of 802 standards
   http://standards.ieee.org/getieee802/
 • IP protocol, Port numbers, etc; http://www.iana.org/numbers.html
 • Internet Engineering Task Force www.ietf.org
 • Security Information http://www.wardrive.net/
 • Windows Security http://www.windowsecurity.com

				
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