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gsmsso.ppt

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  • 1. Using GSM/UMTS for Single Sign-On 28 th October 2003 SympoTIC 2003 Andreas Pashalidis and Chris J. Mitchell
  • 2. Agenda
      • Introduction to SSO.
      • Review of GSM security.
      • How to SSO using GSM.
      • Some Attacks.
      • Conclusions.
  • 3. Agenda
      • Introduction to SSO.
      • Review of GSM security.
      • How to SSO using GSM.
      • Some Attacks.
      • Conclusions.
  • 4. Why do we need SSO ?
    • Current Situation:
    • Network users interact with multiple service providers.
  • 5. Why do we need SSO ?
    • Problems:
    • Usability, security, privacy…
  • 6. What is SSO ?
    • A mechanism that allows users to authenticate themselves to multiple service providers, using only one identity.
  • 7. SSO – How ?
    • Establish trust relationships, common security infrastructure (e.g. PKI), sign contractual agreements…
  • 8. SSO – some examples
    • Kerberos
        • TTP = Kerberos server
        • 1) Authenticates user (password), issues “ticket”.
        • 2) User shows ticket to service provider.
    • Microsoft Passport
        • TTP = www.passport.com
        • 1) Authenticates user (password), installs encrypted cookie.
        • 2) Service Provider reads the cookie.
    • Liberty Alliance
        • TTP = “Identity Provider”
        • 1) Authenticates user, issues “assertion” (XML).
        • 2) Assertion is shown to service provider.
  • 9. Agenda
      • Introduction to SSO.
      • Review of GSM security.
      • How to SSO using GSM.
      • Some Attacks.
      • Conclusions.
  • 10. Review of GSM Security
  • 11. Review of GSM Security
  • 12. Review of GSM Security
  • 13. Review of GSM Security
  • 14. Review of GSM Security
  • 15. Review of GSM Security
  • 16. Review of GSM Security
  • 17. Review of GSM Security
  • 18. Review of GSM Security
  • 19. Review of GSM Security Encrypted under K c If the visited network can decrypt, then the SIM is authentic (IMSI matches K i )
  • 20. Agenda
      • Introduction to SSO.
      • Review of GSM security.
      • How to SSO using GSM.
      • Some Attacks.
      • Conclusions.
  • 21. Architecture - before
  • 22. Architecture – after (1)
  • 23. Architecture – after (2)
  • 24. Architecture
  • 25. Architecture Service providers form trust relationships with the home network.
  • 26. Architecture Singe Sign-On using SIM (IMSI) !
  • 27. SSO Protocol
  • 28. SSO Protocol
  • 29. SSO Protocol
  • 30. SSO Protocol
  • 31. SSO Protocol
  • 32. SSO Protocol
  • 33. SSO Protocol
  • 34. SSO Protocol
  • 35. SSO Protocol
  • 36. Agenda
      • Introduction to SSO.
      • Review of GSM security.
      • How to SSO using GSM.
      • Some Attacks.
      • Conclusions.
  • 37. Replay Attack Attacker could capture this message and replay it later in order to impersonate the user identified by the IMSI.
  • 38. Replay Attack At the time of replay another RAND will be selected by the service provider and the protocol will fail. fresh ! old ! X
  • 39. Reflection Attack The service provider SP “A” is malicious . It wants to impersonate the user to SP “B”.
  • 40. Reflection Attack
  • 41. Reflection Attack
  • 42. Reflection Attack
  • 43. Reflection Attack
  • 44. Reflection Attack
  • 45. Reflection Attack
  • 46. Reflection Attack X
  • 47. Other Attacks
    • SIM theft / cloning
      • SIM PIN is optional!
      • Need two-factor user authentication.
    • Home network server is SPoF
      • Vulnerable to DoS attack.
      • It is assumed that it is well-protected.
    • Attacks on the SP-home network link
      • Link must be integrity-protected and encrypted.
      • SSL/TLS, VPN, IPSec, etc…
  • 48. Agenda
      • Introduction to SSO.
      • Review of GSM security.
      • How to SSO using GSM.
      • Some Attacks.
      • Conclusions.
  • 49. Advantages
    • no user interaction is required.
    • protocol can be repeated many times.
    • simple single logoff.
    • no sensitive information is sent.
    • no major computational overheads.
    • no changes in deployed GSM infrastructure.
    • fraud management extends to SSO.
    • can easily be extended to enable LBS.
  • 50. Disadvantages
    • works only for GSM subscribers.
    • global identifier (IMSI).
    • might incur costs for service providers.
  • 51. Extension for UMTS
  • 52. Thanks! Questions?

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