3GPP TS 33.517 V18 — 5G SCAS for SEAF

Q: What does the Scope section cover in 3GPP TS 33.517 V18 — 5G SCAS for SEAF?

The Scope section provides detailed technical specifications, security considerations, and implementation guidance as documented in 3GPP TS 33.517 V18 — 5G SCAS for SEAF. This content is part of the BLACKLABS 3GPP Security Library.

Q: What does the SEAF Product Class Definition section cover in 3GPP TS 33.517 V18 — 5G SCAS for SEAF?

The SEAF Product Class Definition section provides detailed technical specifications, security considerations, and implementation guidance as documented in 3GPP TS 33.517 V18 — 5G SCAS for SEAF. This content is part of the BLACKLABS 3GPP Security Library.

Q: What does the SEAF-Specific Threats section cover in 3GPP TS 33.517 V18 — 5G SCAS for SEAF?

The SEAF-Specific Threats section provides detailed technical specifications, security considerations, and implementation guidance as documented in 3GPP TS 33.517 V18 — 5G SCAS for SEAF. This content is part of the BLACKLABS 3GPP Security Library.

Q: What does the Security Requirements and Test Cases section cover in 3GPP TS 33.517 V18 — 5G SCAS for SEAF?

The Security Requirements and Test Cases section provides detailed technical specifications, security considerations, and implementation guidance as documented in 3GPP TS 33.517 V18 — 5G SCAS for SEAF. This content is part of the BLACKLABS 3GPP Security Library.

Q: What does the SCAS Test Case Summary section cover in 3GPP TS 33.517 V18 — 5G SCAS for SEAF?

The SCAS Test Case Summary section provides detailed technical specifications, security considerations, and implementation guidance as documented in 3GPP TS 33.517 V18 — 5G SCAS for SEAF. This content is part of the BLACKLABS 3GPP Security Library.

BLACKLABS

3GPP TS 33.517

5G Security Assurance Specification (SCAS) for the SEcurity Anchor Function (SEAF) network product class

V18.3.0 (2024-06) — Release 18 SCAS Product Class

Note: In Rel-15/16/17/18, the SEAF is co-located with the AMF. This SCAS defines requirements for the SEAF function itself, whether co-located or separated.

1. Scope

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Defines security requirements for the SEAF. The SEAF receives K_SEAF from the AUSF and derives K_AMF for the AMF. It anchors the security context in the serving network.

4. SEAF Product Class Definition

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┌──────────┐ ┌──────────┐ ┌──────────┐ │ AUSF │──────►│ SEAF │──────►│ AMF │ └──────────┘ │ (this) │ └──────────┘ K_SEAF │ │ K_AMF │ Derives │ │ K_AMF │ │ from │ │ K_SEAF │ └──────────┘

The SEAF holds K_SEAF, which is the trust anchor for the serving network. From K_SEAF, it derives K_AMF using the ABBA parameter (Anti-Bidding-down Between Architectures).

5. SEAF-Specific Threats

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TR 33.926 §5.3.5 Unauthorized access to K_SEAF anchor key ▶

K_SEAF extraction: Allows attacker to derive all session keys
ABBA manipulation: Forcing downgrade from 5G to 4G security level
K_AMF re-derivation bypass: Reusing old K_SEAF after re-authentication

6. Security Requirements and Test Cases

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TC_SEAF_KEY_DERIVATION

CRITICAL

Procedure

Verify K_SEAF is stored in protected memory
Verify K_AMF derivation uses correct ABBA parameter
Verify old K_SEAF is deleted after new authentication completes
Verify K_SEAF is unique per authentication (not reused across sessions)

TC_SEAF_ABBA_VALIDATION