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SIP, Security & Threat Models

SIP, Security & Threat Models. Dr. Samir Chatterjee School of Information Science Claremont Graduate University Claremont, CA 91711 Sip://s amir.chatterjee@cgu.edu 909-607-4651. Outline of Talk. Videoconferencing Environment SIP – What, Why, How? A Security Framework

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SIP, Security & Threat Models

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  1. SIP, Security & Threat Models Dr. Samir Chatterjee School of Information Science Claremont Graduate University Claremont, CA 91711 Sip://samir.chatterjee@cgu.edu 909-607-4651 SURA/ViDe 4th Annual Workshop

  2. Outline of Talk • Videoconferencing Environment • SIP – What, Why, How? • A Security Framework • Various Threat Models • Summary SURA/ViDe 4th Annual Workshop

  3. H.323 Gatekeeper PSTN Campus B H.323 terminal Worldcom SIP gateway LDAP Dir serv User Agent C Internet-2 (A laptop) Legacy phone Campus A Cell phone MCU SIP Server User agent B User agent A VC Components (Proxy, Registrar, Location) SURA/ViDe 4th Annual Workshop

  4. SIP (The IETF Standard) • Session Initiation Protocol is a signaling standard approved by IETF for real-time multimedia session establishment. • Sessions can be voice, video or instant messaging and is described by SDP. • Basic components: • User Agent (UA): works on behalf of users to set up calls • Proxy Servers (PS): keeps track of location of end-points • Registrar: Each UA registers to inform current location and preferred reachability information • SIP also has been approved for 3G wireless systems. SURA/ViDe 4th Annual Workshop

  5. I am “Samir Chatterjee”. Today I will be reachable at Sip:Samir@131.160.1.112 SIP Entities Location Server (Not part of SIP entity but is required. Can use LDAP server. I am using Oracle 8.0 at CGU to hold user accounts) SIP UA I am “Doug Sicker”. Today I can be reached at Sip:Doug@131.160.2.113 SIP server (registrar and proxy) • First Register • Make a call (voice, video) • Hang up. SIP UA SURA/ViDe 4th Annual Workshop

  6. Making a Call in SIP LS (2) Where is Samir reachable? (3) Try sip:Samir@131.160.2.114 (1) Invitation to a session for Sip:Samir.chatterjee@cgu.edu SIP proxy At cgu.edu (4) Invitation to a session for Sip:Samir@131.160.2.114 laura@131.160.1.112 UA to Proxy interaction SURA/ViDe 4th Annual Workshop

  7. Inter-Realm SIP SIP Proxy Bob on a desktop With a SIP VC-UA Alice on a desktop With a SIP VC-UA SIP Proxy INVITE If Bob is valid, Forward INVITE Realm CGU.EDU Can I trust you? Realm: Microsoft.com Sure, I belong to the same club Invite from Bob 180 Ringing 180 Ringing 180 Ringing 200 OK SURA/ViDe 4th Annual Workshop

  8. Security Framework SURA/ViDe 4th Annual Workshop

  9. Classic Threat Models • Registration Hijacking – A registrar assesses the identity of a UA. The From header of a SIP request can be arbitrarily modified and hence open to malicious registration. • Impersonating a server – A UA contacts a Proxy server to deliver requests. The server could be impersonated by an attacker. Mobility in SIP further complicates this. • Tampering with message bodies SURA/ViDe 4th Annual Workshop

  10. More threats • Tearing down sessions – insert a BYE • Denial of Service attacks - Denial of service attacks focus on rendering a particular network element unavailable, usually by directing an excessive amount of network traffic at its interfaces.In much architecture SIP proxy servers face the public Internet in order to accept requests from worldwide IP endpoints. SIP creates a number of potential opportunities for distributed denial of service attacks that must be recognized and addressed by the implementers and operators of SIP systems SURA/ViDe 4th Annual Workshop

  11. Challenges • Authentication – SIP currently has the HTTP style digest mechanism. But it is not enough. • We need a single sign-on authentication mechanism. Shiboleth may be the approach to take. • Authorization using ACLs — the read/write/execute controls that are embedded in file systems • New approaches - Traditional access control models are broadly categorized as discretionary access control (DAC) and mandatory access control (MAC) models. New models such as role-based access control (RBAC) and task-based access control (TBAC) have been proposed to address the security requirements. SURA/ViDe 4th Annual Workshop

  12. Summary • VidMid-VC is leading the way on solving these important security stuff. • See http://middleware.internet2.edu/video Thank You. Any Questions? SURA/ViDe 4th Annual Workshop

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