Security: Mobile Core - GTP (GPRS Tunnelling Protocol)

GTP is the core protocol for carrying subscriber data and control information in 4G and 5G networks. It is a prime target for user data breakout, TEID-based spoofing, and malicious encapsulation.

🛡️ Tactical Domain Mapping: GTP Security

GTP Area / Component	Functional Security Objective	ITU Rec (Official PDF)	3GPP Equiv	3GPP Target
GTP-U (User Plane)	Tunnel Isolation & Integrity	X.1039	TS 33.117	/security
GTP-C (Control Plane)	Session Mgmt Security	X.1038	TS 29.274	/interfaces
TEID Spoofing	Non-repudiation & Authenticity	X.805	GSMA FS.37	/audit
Protocol Filtering	Multi-Layer Availability	Y.2770	GSMA FS.31	/security

🚦 Tactical Release Realizations

For release-specific 3GPP implementations of GTP security (GTPv2 vs. GTPv3), see the generation bridges:

🏛️ Strategic Alignment

ITU Series: Primarily mapped to itu-t Series-X (Data Networks & Security) and itu-t Series-Y (GII/5G).
Study Groups: SG17 (Security) and SG13 (Future Networks/5G).

🧪 Penetration Testing Tools

GTP-Scan: Tool for identifying open GTP-U/C ports and interfaces.
Scapy-GTP: Python-based packet manipulation for GTP fuzzer development.
Wireshark-GTP: Protocol analyzer for capturing and dissecting GTP-C/U tunnels.

📋 Field Audit Checklist

[ ] GTP-C Filtering: Are incoming GTP-C messages strictly filtered based on GSMA FS.31?
[ ] TEID Randomization: Are Tunnel Endpoint Identifiers (TEIDs) randomized to prevent spoofing?
[ ] GTP-U Integrity: Is integrity protection enabled for GTP-U tunnels on the N3 interface (if supported by UE)?
[ ] Roaming Hub Verification: Are GTP sessions from unauthorized roaming hubs blocked at the edge?
[ ] GTP-in-GTP Detection: Is the GGSN/UPF configured to drop packets with double-encapsulated GTP headers?

!IMPORTANTFS.31 Implementation Note: The GSMA FS.31 (GTP Security Management) provides specific rules for filtering GTP messages from inter-operator Roaming hubs.

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