The FS.38 framework focuses heavily on active security auditing and continuous monitoring. Rather than treating SIP as an isolated application layer protocol, the document analyzes the entire ecosystem supporting SIP traffic.
This area covers user equipment accessing the SIP network through cellular or Wi-Fi mediums using traditional SIM configurations. FS.38 intersects with here to analyze signaling vectors across the IP Multimedia Subsystem (IMS) when traffic traverses unsecure access nodes. 3. SIP Interconnect
: Because SIP is an open, text-based protocol similar to HTTP, it is highly accessible to hackers. Traditional internet-borne attacks can now easily target telecom infrastructures. gsma fs.38
The standard provides a comprehensive catalogue of potential attacks, ranging from attempts to disrupt service availability to those aimed at accessing confidential communications or executing fraudulent activities. These vulnerabilities persist in modern networks; for example, despite GSMA guidelines, VoLTE remains susceptible to threats due to its open, all-IP architecture, and roaming setups.
| GSMA PRD | Title / Focus Area | What It Covers | | :--- | :--- | :--- | | | SS7 and SIGTRAN Network Security | Threat analysis, attack methods, and countermeasures for SS7 signaling | | FS.19 | Diameter Interconnect Security | Potential diameter-based attacks and mitigation strategies | | FS.20 | GPRS Tunnelling Protocol (GTP) Security | Security analysis for the GTP control plane | | FS.22 | VoLTE Security | Security analysis and recommendations specifically for VoLTE | | FS.36 | 5G Interconnect Security | Security considerations for 5G network interconnections | | FS.37 | GTP-U Security | Security recommendations for the GTP user plane | | FS.38 | SIP Network Security | Comprehensive guide to SIP-based attacks and countermeasures | | FS.39 | 5G Fraud Risks Guide | Describes potential attacks against 5G networks and their services | The FS
: Ancillary infrastructure including SIP endpoint provisioning servers and administrative user portals. 2. Protocol Correlation and Interconnect Signaling
: Encourages the use of real-time threat intelligence, pre-configured heuristics, and Deep Packet Inspection (DPI) with machine learning to proactively identify emerging threats. Holistic Testing Protocol Correlation and Signaling Firewalls
Operating under the assumption that an attacker may eventually bypass peripheral defenses, FS.38 dictates strict validation for internal nodes. This covers core infrastructure elements located directly behind the SBCs, such as: Call Session Control Functions (P-CSCF, I-CSCF, S-CSCF) Telephony Application Servers (TAS) Media Gateway Control Functions (MGCF) 4. Non-SIP Supporting Nodes
: Stopping port scans and SIP fingerprinting used to map network vulnerabilities. Routing Attack Mitigation
FS.38 is the most sophisticated attempt yet to create the "roaming" for edge computing (similar to what SS7 did for voice). However, it currently solves the technical problem of federation better than the commercial problem of federation. Expect widespread deployment only when cross-operator billing standards are added in a future release (FS.38.2). For now, it is excellent for reference architecture but requires heavy customization for production.
Session Border Controllers function as application-aware firewalls. FS.38 demands that SBCs run deep packet inspection (DPI) to parse incoming SIP requests, strip internal network topologies out of response headers, and enforce explicit rate-limiting to suppress fuzzing and brute-force registration attempts. Protocol Correlation and Signaling Firewalls