1 using gsm/umts for single sign-on 28 th october 2003 sympotic 2003 andreas pashalidis and chris j....
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Using GSM/UMTS forSingle Sign-On
28th October 2003SympoTIC 2003
Andreas Pashalidis and Chris J. Mitchell
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Agenda
Introduction to SSO. Review of GSM security. How to SSO using GSM. Some Attacks. Conclusions.
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Agenda
Introduction to SSO. Review of GSM security. How to SSO using GSM. Some Attacks. Conclusions.
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Why do we need SSO ?Current Situation:
Network users interact with multiple service providers.
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Why do we need SSO ?Problems:
Usability, security, privacy…
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What is SSO ?
A mechanism that allows users to authenticate themselves to
multiple service providers, using only one identity.
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SSO – How ?Establish trust relationships, common security
infrastructure (e.g. PKI), sign contractual agreements…
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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.
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Agenda
Introduction to SSO. Review of GSM security. How to SSO using GSM. Some Attacks. Conclusions.
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Review of GSM Security
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Review of GSM Security
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Review of GSM Security
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Review of GSM Security
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Review of GSM Security
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Review of GSM Security
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Review of GSM Security
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Review of GSM Security
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Review of GSM Security
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Review of GSM Security
Encrypted under Kc
If the visited network can decrypt, then the SIM is authentic (IMSI matches Ki)
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Agenda
Introduction to SSO. Review of GSM security. How to SSO using GSM. Some Attacks. Conclusions.
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Architecture - before
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Architecture – after (1)
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Architecture – after (2)
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Architecture
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Architecture
Service providers form trust relationships with the home
network.
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Architecture
Singe Sign-On using SIM (IMSI) !
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SSO Protocol
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SSO Protocol
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SSO Protocol
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SSO Protocol
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SSO Protocol
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SSO Protocol
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SSO Protocol
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SSO Protocol
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SSO Protocol
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Agenda
Introduction to SSO. Review of GSM security. How to SSO using GSM. Some Attacks. Conclusions.
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Replay Attack
Attacker could capture this
message and replay it later in
order to impersonate the user identified
by the IMSI.
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Replay Attack
At the time of replay another
RAND will be selected by the service provider and the protocol
will fail.
fresh !
old ! X
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Reflection Attack
The service provider SP “A” is malicious.
It wants to impersonate the user to SP “B”.
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Reflection Attack
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Reflection Attack
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Reflection Attack
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Reflection Attack
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Reflection Attack
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Reflection Attack
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Reflection Attack
X
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Other AttacksSIM 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…
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Agenda
Introduction to SSO. Review of GSM security. How to SSO using GSM. Some Attacks. Conclusions.
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Advantages
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Disadvantages
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Extension for UMTS
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Thanks!Questions?