Telecom Penetration Testing Methodologies

         # Searching for potentially exposed 5G Core AMF endpoints
shodan search 'port:38412 SCTP'
# Searching for exposed Diameter nodes
shodan search 'port:3868 Diameter'
# Searching for exposed GTP-C endpoints (very dangerous if found)
shodan search 'port:2123 GTPv2'
      

The telecom pentesting lifecycle follows six distinct phases, each targeting a different layer of the network architecture:

Phase 1: Intelligence Gathering and OSINT

Before transmitting a single packet, attackers map the target's footprint. In telecom, this goes beyond finding IP subnets — it requires understanding the operator's entire technology stack, vendor relationships, and interconnect topology.

Passive OSINT Sources

         # Enumerate MNO's public-facing infrastructure
# 1. Find the operator's ASN
whois -h whois.radb.net -- '-i origin AS12345'
# 2. Reverse DNS for management interfaces
for ip in $(host -t A *.operator.com | awk '{print $NF}'); do
nmap -sV -p 80,443,3000,8080,8443,9090 $ip
done
# 3. Certificate transparency log analysis
curl 'https://crt.sh/?q=%.operator.com&output=json' | jq '.[].name_value'
      

Phase 2: Radio Access Network (RAN) Exploitation

The most accessible part of any mobile network is the air interface. Any attacker with a $300 SDR can receive and analyze broadcast signaling — and with a properly configured lab, they can transmit.

RAN Attack Vectors

Rogue Base Station Deployment Methodology

1. Perform spectrum analysis to identify the target operator's active frequencies and strongest serving cells
2. Configure the rogue eNB/gNB to broadcast on the same PLMN with a stronger signal
3. UEs perform cell reselection to the rogue cell
4. Capture IMSI/IMEI during initial attach (pre-authentication in 4G; SUCI in 5G — requires key compromise for SUPI extraction)
5. Execute downgrade attacks by refusing to support strong security algorithms in the SecurityModeCommand

Phase 3: Signaling and Interconnect Attacks (SS7/Diameter)

The "soft underbelly" of global telecommunications is the interconnect network used for roaming. Despite decades of documented vulnerabilities, SS7 vulnerabilities and Diameter protocol signaling networks remain exploitable through roaming interconnects and compromised IPX providers.

SS7 Attack Categories

Diameter Attack Categories

Phase 4: The 5G Core (5GC) Cloud-Native Assault

As networks transition to 5G Standalone (SA), the core becomes a Kubernetes cluster running HTTP/2 microservices. This imports the entire cloud-native threat landscape into telecom infrastructure.

5GC Attack Methodology

1. API Discovery: Enumerate NF service endpoints via NRF queries or SCP traffic interception
2. BOLA Exploitation: Test subscriber data enumeration through SUPI iteration against UDM APIs
3. NRF Poisoning: Attempt rogue NF registration to intercept authentication traffic
4. Container Escape: Exploit kernel vulnerabilities from compromised border-facing NFs (AMF)
5. Lateral Movement: Pivot through the Kubernetes cluster to reach high-value NFs (AUSF, UDM)
6. Slice Pivot: Test 5G network slicing security by attempting to access resources in adjacent network slices

<CodeBlock language="bash" is-terminal code=" # Example: Scanning for exposed 5G NF APIs within a compromised cluster # After initial access to any pod in the 5gc namespace: # 1. Discover NRF endpoint curl -s http://nrf.5gc.svc:80/nnrf-disc/v1/nf-instances?target-nf-type=UDM # 2. Query UDM for subscriber data (BOLA test) curl -s -H 'Authorization: Bearer '
http://udm.5gc.svc:80/nudm-sdm/v1/imsi-001010123456789/am-data # 3. Attempt NRF registration with rogue NF profile curl -s -X POST http://nrf.5gc.svc:80/nnrf-nfm/v1/nf-instances/rogue-ausf
-H 'Content-Type: application/json'
-d '{"nfType":"AUSF","nfStatus":"REGISTERED","priority":1}'" />

II. Specialized Telco Frameworks and Tools

Telecom red teaming requires specialized, often proprietary, toolsets. Standard enterprise pentesting tools (Nessus, Metasploit) are largely ineffective against telecom-specific protocols and interfaces.

Tool Categories

Comprehensive Tooling Matrix

III. The MITRE FiGHT Framework Integration

Finding vulnerabilities is only half the battle; remediating them without causing a nationwide outage is the true challenge. Every finding from a telecom pentest must be contextualized within a standard threat model that SOC teams can operationalize.

TelcoSec aligns all offensive findings with the MITRE FiGHT (5G Hierarchy of Threats) framework — the telecom-specific equivalent of MITRE ATT&CK. This ensures that every finding is mapped to standardized TTPs, enabling operators to build detection rules for SIEM platforms and prioritize remediation based on adversarial impact.

FiGHT Tactic Mapping for Telecom Pentests

IV. Reporting and Remediation Framework

Telecom pentest reports must be structured differently from standard IT assessments because the audience spans security engineers, network architects, regulatory compliance teams, and executive leadership.

Report Structure

1. Executive Summary: Business impact in terms of subscriber count at risk, regulatory exposure (GDPR, national security frameworks), and financial liability
2. Technical Findings: Each finding includes:
   • Attack vector and kill chain
   • MITRE FiGHT TTP mapping
   • Evidence (PCAP captures, API responses, screenshots)
   • CVSS score (adapted for telecom context)
   • Remediation priority (P0–P4)
3. Remediation Roadmap: Phased remediation with timelines:
   • P0 (Immediate): Exposed management interfaces, default credentials, unfiltered SS7 vulnerabilities signaling
   • P1 (7 days): Missing mTLS in 5G SBA vulnerabilities, overly permissive NetworkPolicies
   • P2 (30 days): Incomplete Diameter DEA/DRA filtering, weak OAuth scoping
   • P3 (90 days): Missing eBPF monitoring, incomplete 5G network slicing security
   • P4 (Strategic): Architecture redesign, per-SUPI authorization, zero-trust mesh
4. Regulatory Mapping: Findings mapped to GSMA NESAS, ENISA 5G security controls, and national certification schemes

V. Authoritative References

VI. Frequently Asked Questions

Conclusion & Next Steps

Telecom penetration testing requires a hybrid skill set: RF engineering, legacy protocol manipulation (SS7 vulnerabilities, Diameter protocol), advanced cloud-native Kubernetes exploitation (5G SBA vulnerabilities), and deep knowledge of 3GPP specifications. Minimum viable compliance scanning is no longer sufficient to protect national critical infrastructure against advanced threat actors.

The evolution of the attack surface demands continuous reassessment:

1. Quarterly: Signaling firewall rule validation and Diameter protocol interconnect testing
2. Semi-annually: RAN security assessment including IMSI catchers resilience
3. Annually: Full 5GC cloud-native assessment with container escape and 5G network slicing security testing
4. On-change: Assessment after any major infrastructure upgrade, vendor swap, or roaming agreement modification

When to Engage a Professional Telecom Pentesting Firm

In-house teams can execute many phases of this methodology — particularly OSINT, protocol analysis, and signaling firewall validation. However, certain scenarios warrant engaging a specialist telecom penetration testing provider:

• Regulatory compliance mandates (GSMA NESAS, ETSI TS 33.117, national telecom regulator requirements) require independent third-party assessments
• New technology deployment — launching 5G SA, opening new roaming corridors, or deploying O-RAN introduces unfamiliar attack surfaces that benefit from external expertise
• Post-incident validation — following a suspected SS7 exploit, SIM swap campaign, or interconnect compromise, independent verification of remediation is essential
• No internal signaling competency — SS7, Diameter, and GTP require protocol-specific expertise that few enterprise security teams possess
• Board or investor assurance — external assessment reports carry greater weight with regulators and investors than internal audits

When evaluating a telecom security assessment provider, verify that their team has documented experience across signaling protocols, RAN testing, and cloud-native 5G core environments — not generic network penetration testing rebranded as telecom.

Is your core hardened against an advanced threat actor? Leverage TelcoSec's offensive capabilities to preemptively discover critical vulnerabilities in your deployment. Build your own research capabilities with our private LTE/5G lab, or explore the TelcoSec research library for deep-dive technical intelligence.