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Class10

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Transcript

  • 1. Week 10 Short Lecture Lab
  • 2. POP Quiz <ul><li>What is the security spec for 802.11? </li></ul><ul><li>Define TKIP? </li></ul><ul><li>How can you locate a rogue AP? </li></ul><ul><li>Which tool is used to attack ipsec deployments? </li></ul><ul><li>What is VOID11 used for? </li></ul><ul><li>What encryption standard is WEP based on? </li></ul>
  • 3. Wireless Is Addicting Once You Use It You Can’t Live without It
  • 4. So what is the “business impact” of security? <ul><li>According to the Computer Crime and Security Survey 2002, by the Computer Security Institute (CSI) and the FBI: </li></ul><ul><ul><li>44% of respondents (223 total) were able to quantify financial losses of $455M, or $2.05M per survey respondent </li></ul></ul><ul><ul><li>90% detected computer security breaches within the last 12 months. 80% acknowledged financial loss due to breach. </li></ul></ul><ul><ul><li>85% detected computer viruses </li></ul></ul><ul><ul><li>40% experienced Denial-of-Service attacks </li></ul></ul>Source: FBI and Computer Security Institute (CSI) Computer Crime and Security Survey 2002 Link: http://www.gocsi.com Security Breaches Have Real Costs
  • 5. Baseline Technology Standards, Encryption, Protection Product security features Security tools and products Planning for Security Prevention Detection Reaction Technology, Process, People Dedicated Staff Training Security - a mindset and a priority
  • 6. <ul><li>Internet Authentication Server (IAS) </li></ul><ul><ul><li>Acts as a RADIUS proxy </li></ul></ul><ul><ul><li>Handle authentication requests </li></ul></ul><ul><li>Remote Authentication Dial-in User Server (RADIUS) </li></ul><ul><li>Extensible Authentication Protocol (EAP) </li></ul>Intro to Wireless Networks Tools and Technologies
  • 7. Setting up a Wireless Network Authentication Services <ul><li>Open System </li></ul><ul><ul><li>Does not provide authentication </li></ul></ul><ul><ul><li>Identification using the wireless adapter's MAC address </li></ul></ul><ul><li>Shared Key </li></ul><ul><ul><li>Verifies that an authenticating wireless client has knowledge of a shared secret key </li></ul></ul><ul><ul><li>Similar to preshared key authentication in Internet Protocol security (IPsec) </li></ul></ul>
  • 8. Setting up a Wireless Network Authentication <ul><li>EAP-TLS </li></ul><ul><ul><li>Does not require any dependencies on the user account password </li></ul></ul><ul><ul><li>Authentication occurs automatically, with no intervention by the user </li></ul></ul><ul><ul><li>Uses certificates, providing a strong authentication scheme </li></ul></ul>
  • 9. <ul><li>IAS as a RADIUS proxy security considerations </li></ul><ul><ul><li>Shared secrets </li></ul></ul><ul><ul><li>Firewall configuration </li></ul></ul><ul><ul><li>Message Authenticator attribute </li></ul></ul><ul><ul><li>Using IPSec filters to lock down IAS proxy servers </li></ul></ul><ul><ul><li>Password Authentication Protocol (PAP) </li></ul></ul>Setting up a Wireless Network Active Directory
  • 10. Setting up a Wireless Network Security Issues With 802.11 <ul><li>No per-packet authentication </li></ul><ul><li>Vulnerability to disassociation attacks </li></ul><ul><li>No user identification and authentication </li></ul><ul><li>No central authentication, authorization, and accounting support </li></ul><ul><li>RC4 stream cipher is vulnerable to known plain text attacks </li></ul><ul><li>Some implementations derive WEP keys from passwords </li></ul><ul><li>No support for extended authentication </li></ul>
  • 11. Security in a Wireless World Basic Steps to Authentication CHALLENGE ID Traffic Traffic Traffic STA AP
  • 12. RADIUS ID REQUEST SUCCESS KEY Security in a Wireless World Basic Steps to Authentication STA AP CREDENTIALS
  • 13. Dynamic WEP Key Management EAPOL-Start EAP-Response/Identity EAP-Request Radius-Access-Request Radius-Access-Challenge EAP-Response (Credential) Radius-Access-Request EAP-Success Access Blocked Radius-Access-Accept RADIUS EAPOW 802.11 802.11 Associate Access Allowed EAPW-Key (WEP) Laptop computer RADIUS Fast Ethernet EAP-Request/Identity
  • 14. Security in a Wireless World RADIUS Best Practices <ul><li>Deployment </li></ul><ul><ul><li>Implement EAP and EAP types that use strong authentication methods </li></ul></ul><ul><ul><li>Implement authentication methods that use mutual authentication </li></ul></ul><ul><ul><li>If you implement PAP authentication, disable its use by default </li></ul></ul><ul><ul><li>If you implement CHAP authentication, use a strong CHAP challenge </li></ul></ul>
  • 15. Security in a Wireless World RADIUS Best Practices <ul><li>Implementation </li></ul><ul><ul><li>Strong shared secrets </li></ul></ul><ul><ul><li>Use a different shared secret </li></ul></ul><ul><ul><li>Require Message-Authenticator attribute </li></ul></ul><ul><ul><li>Disable the use of LAN Manager encoding </li></ul></ul><ul><ul><li>A strong EAP and an EAP type </li></ul></ul>
  • 16. Pros & Cons of Wireless Security
  • 17. Pros & Cons of Wireless Security
  • 18. Six-Steps for Wireless Security <ul><li>Enable 128-bit session encryption </li></ul><ul><li>Configure RADIUS server authentication </li></ul><ul><li>Force 30-minute periodic authentication for all users </li></ul><ul><li>* Source Computerworld </li></ul><ul><li>Require use of VPN to access critical resources </li></ul><ul><li>Restrict LAN access rights by role </li></ul><ul><li>Implement two-factor authentication scheme using access tokens </li></ul>
  • 19. Challenge Message <ul><li>Radius server sends challenge to client via access point </li></ul><ul><li>This challenge packet will vary for each authentication attempt </li></ul><ul><li>The challenge is pulled from information contained a table of known secrets </li></ul><ul><li>New challenge can be sent at intervals based on Radius server settings, or upon client roaming </li></ul>
  • 20. Calculated HASH <ul><li>Client responds with a calculated value using a “one way hash” function </li></ul><ul><li>This value is derived from a known secrets list </li></ul>Start
  • 21. Authentication Granted/Denied <ul><li>Radius server checks response against it own calculated hash </li></ul><ul><li>If it matches, then authentication is acknowledged to AP and client </li></ul><ul><li>If authentication is not achieved, the AP will not permit any traffic for that client to pass </li></ul>
  • 22. Six-Steps for Wireless Security <ul><li>Enable 128-bit session encryption </li></ul><ul><li>Configure RADIUS server authentication </li></ul><ul><li>Force 30-minute periodic authentication for all users </li></ul><ul><li>* Source Computerworld </li></ul><ul><li>Require use of VPN to access critical resources </li></ul><ul><li>Restrict LAN access rights by role </li></ul><ul><li>Implement two-factor authentication scheme using access tokens </li></ul>
  • 23. Why LEAP ? <ul><li>Cisco Lightweight EAP (LEAP) Authentication type </li></ul><ul><ul><li>No native EAP support currently available on legacy operating systems </li></ul></ul><ul><ul><li>EAP-MD5 does not do mutual authentication </li></ul></ul><ul><ul><li>EAP-TLS (certificates/PKI) too intense for security baseline feature-set </li></ul></ul><ul><ul><li>Quick support on multitude of host systems </li></ul></ul><ul><ul><li>Lightweight implementation reduces support requirements on host systems </li></ul></ul><ul><ul><li>Need support in backend for delivery of session key to access points to speak WEP with client </li></ul></ul>
  • 24. AT&T Labs Technical Report TD-4ZCPZZ. <ul><ul><li>Using the Fluhrer, Mantin, and Shamir paper a practical test was conducted by AT&T Labs. In this document the statement is made: </li></ul></ul><ul><ul><li>There do exist proprietary solutions that allow each mobile node to use a distinct WEP key, most notably Cisco’s LEAP protocol. LEAP sets up a per-user, per-session WEP key when a user first authenticates to the network. This complicates the attack, but does not prevent it so long as a user’s ”session” lasts sufficiently long. </li></ul></ul>
  • 25. Cisco LEAP Deployment <ul><li>Radius </li></ul><ul><li>Cisco Secure ACS 2.6 </li></ul><ul><li>Authentication database </li></ul><ul><li>Can use Windows user database </li></ul><ul><li>Radius DLL </li></ul><ul><li>LEAP Authentication support </li></ul><ul><li>MS-MPPE-Send-key support </li></ul><ul><li>EAP extensions for Radius </li></ul><ul><li>EAP Authenticator </li></ul><ul><li>EAP-LEAP today </li></ul><ul><li>EAP-TLS today </li></ul><ul><li>… </li></ul>Client/Supplicant Authenticator Backend/Radius server LEAP Radius Server Laptop Computer with LEAP Supplicant Wireless EAP Access Point Backbone <ul><li>Network Logon </li></ul><ul><li>Win 95/98 </li></ul><ul><li>Win NT </li></ul><ul><li>Win 2K </li></ul><ul><li>Win CE </li></ul><ul><li>MacOS </li></ul><ul><li>Linux </li></ul><ul><li>Driver for OS x </li></ul><ul><li>LEAP Authentication support </li></ul><ul><li>Dynamic WEP key support </li></ul><ul><li>Capable of speaking EAP </li></ul>Ethernet
  • 26. Security Evolution <ul><li>Static keying </li></ul><ul><ul><li>WEP (Wired Equivalent Privacy) </li></ul></ul><ul><ul><li>TKIP (Temporal Key Integrity Protocol) </li></ul></ul><ul><ul><li>AES (Advanced Encryption Standard) </li></ul></ul><ul><li>IEEE 802.1x dynamic keying (EAP-TLS, EAP-TTLS, PEAP) </li></ul><ul><ul><li>IEEE 802.1x dynamic WEP keying </li></ul></ul><ul><ul><li>IEEE 802.1x dynamic TKIP keying </li></ul></ul><ul><ul><li>IEEE 802.1x dynamic AES keying </li></ul></ul><ul><li>VPN (Virtual Private Network) over WLAN </li></ul>
  • 27. TKIP <ul><li>Unique dynamic TKIP key by mixing WEP keys with MAC address. </li></ul><ul><li>MIC (Message Integrity Code) prevents hackers from forging packets in the air. </li></ul>
  • 28. IEEE 802.11i <ul><li>IEEE802.1x (EAP-TLS, EAP-TTLS, PEAP) </li></ul><ul><li>TKIP </li></ul><ul><li>AES-CCMP </li></ul><ul><ul><li>Needs new hardware. </li></ul></ul><ul><li>Secure IBSS (Ad-hoc) </li></ul><ul><li>Secure handoff </li></ul>
  • 29. IEEE 802.1x in Action (EAP-MD5) Notebook Access Point RADIUS Server EAP-Response/Identity (I am Bernard) Radius-Access-Request (A guy called Bernard wants to come into the network) EAP-Response[credentials] (My password is XXXXX) EAP-Request (Tell me your password) EAP-Success (Welcome!) Radius-Access-Challenge (Tell me his password) EAPOL-Start (I would like to connect to the network!) Radius-Access-Request (His password is XXXXX) Radius-Access-Accept (Ok! Let him in) EAP-Request/Identity (Who are you?)
  • 30. Community Hacking Efforts <ul><li>Warchalking : Leaving cryptic symbols to inform others about “free” WLAN connections </li></ul><ul><li>More hype than hot </li></ul>
  • 31. <ul><li>Wired Equivalent Privacy (WEP) </li></ul><ul><ul><li>Provides encryption based on RC-4 cipher </li></ul></ul><ul><li>Wireless Protected Access (WAP) </li></ul><ul><ul><li>Uses dynamic keys and advanced encryption </li></ul></ul><ul><li>802.1x </li></ul><ul><ul><li>Provides authentication using Extensible Authentication Protocol (EAP) </li></ul></ul><ul><li>802.11i </li></ul><ul><ul><li>Advanced encryption and authentication </li></ul></ul>Built-in WLAN Security WLAN Firmware Security Will Not Be Enough to Secure Wireless
  • 32. 802.11i and WPA <ul><li>Uses 802.1x authentication </li></ul><ul><li>Uses Temporal Key Integrity Protocol (TKIP) to dynamically change encryption keys after 10,000 packets are transferred </li></ul><ul><li>Uses Advanced Encryption Standard (AES) encryption, which is much better than WEP </li></ul><ul><li>A subset of 802.11i, Wi-Fi Protected Access (WAP) is available as a firmware upgrade today </li></ul>
  • 33. 802.11i and WPA Pitfalls <ul><li>Keys can be cracked using much less than 10,000 packets </li></ul><ul><li>Michael feature — shuts down AP if it receives two login attempts within one second. Hackers can use this to perpetrate a DoS attack. </li></ul><ul><li>802.11i is yet to be released (Sometime in 2003?) </li></ul>
  • 34. Quiz
  • 35. Homework <ul><li>Describe Radius authentication in your own words. </li></ul>

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