TR 33.978
Security aspects of early IP Multimedia Subsystem (IMS)
V7.0.0 (Wzip)
2007/06 29 p.
V6.6.0
2006/12 29 p.
- Rapporteur:
- Mr. Howard, Peter
full Table of Contents for TR 33.978 Word version: 7.0.0
0 Introduction p. 4
3GPP IMS provides an IP-based session control capability based on the SIP protocol. IMS can be used to enable services such as push-to-talk, instant messaging, presence and conferencing. It is understood that "early" implementations of these services will exist that are not fully compliant with 3GPP IMS. For example, it has been recognized that although 3GPP IMS uses exclusively IPv6, as specified in clause 5.1 of TS 23.221, there will exist IMS implementations based on IPv4 (TR 23.981).
Non-compliance with IPv6 is not the only difference between early IMS implementations and fully 3GPP compliant implementations. In particular, it is expected that there will be a need to deploy some IMS-based services before products are available which fully support the 3GPP IMS security features defined in TS 33.203. Non-compliance with TS 33.203 security features is expected to be a problem mainly at the UE side, because of the potential lack of support of the USIM/ISIM interface (especially in 2G-only devices) and because of the potential inability to support IPsec on some UE platforms.
Although full support of TS 33.203 security features is preferred from a security perspective, it is acknowledged that early IMS implementations will exist which do not support these features. Therefore, there is a need to ensure that simple, yet adequately secure, mechanisms are in place to protect against the most significant security threats that will exist in early IMS implementations.
1 Scope p. 5
The present document documents an interim security solution for early IMS implementations that are not fully compliant with the IMS security architecture specified in TS 33.203. For security reasons, the provisions in this TR only apply to IMS procedures used over the 3GPP PS domain.
2 References p. 5
3 Definitions, symbols and abbreviations p. 6
4 Requirements p. 8
5 Threat scenarios p. 8
5.1 Impersonation on IMS level using the identity of an innocent user p. 8
5.2 IP spoofing p. 9
5.3 Combined threat scenario p. 9
6 Specification p. 9
6.1 Overview p. 9
6.1.1 Security mechanism p. 9
6.1.2 Restrictions imposed by early IMS security p. 10
6.1.3 Early IMS security and logical entities p. 11
6.2 Detailed specification p. 11
6.2.1 GGSN-HSS interaction p. 11
6.2.2 Protection against IP address spoofing in GGSN p. 12
6.2.3 Impact on IMS registration and authentication procedures p. 12
6.2.3.1 Procedures at the UE p. 12
6.2.3.2 Procedures at the P-CSCF p. 12
6.2.3.2.1 Registration p. 13
6.2.3.2.2 General treatment for all dialogs and standalone transactions excluding REGISTER requests p. 13
6.2.3.3 Procedures at the I-CSCF p. 13
6.2.3.4 Procedures at the S-CSCF p. 13
6.2.4 Identities and subscriptions p. 14
6.2.5 Impact on Cx Interface p. 15
6.2.5.1 User registration status query p. 15
6.2.5.2 S-CSCF registration/deregistration notification p. 15
6.2.5.3 Authentication procedure p. 15
6.2.6 Interworking cases p. 16
6.2.7 Message flows p. 18
6.3 Security mechanism for HTTP services p. 22
A Comparison with an alternative approach - HTTP Digest p. 26
$ Change history p. 27
