Methodology
SS7 security testing approach
Attack Vectors
Common SS7 vulnerabilities
Exploits
Technical exploitation details
Interactive Flow
Visual attack simulations
SS7 Protocol Security Overview
The Signaling System No. 7 (SS7) protocol suite is the backbone of global telecommunications, enabling mobile roaming, call setup, SMS delivery, and billing operations across operator networks worldwide. Originally designed in the 1970s with a focus on reliability rather than security, SS7 now faces significant security challenges in today's interconnected world.
Critical Security Impact
SS7 vulnerabilities can lead to location tracking, call and SMS interception, service disruption, and fraud. These attacks can be executed remotely with minimal resources by attackers with SS7 network access.
Key Vulnerability Factors
- Lack of authentication mechanisms in the original protocol design
- No encryption for signaling messages
- Trust-based network architecture that assumes all connected operators are legitimate
- Limited access controls between interconnected networks
- Difficulty implementing security patches across global infrastructure
SS7 Network Evolution
Traditional SS7
Circuit-switched networks with physical point codes
SIGTRAN
SS7 over IP networks with enhanced transport
Diameter
Next-generation protocol for 4G/LTE networks
Signaling Transfer Points (STPs)
Network nodes that route SS7 messages between different networks
Vulnerable to unauthorized access and message manipulation
Home Location Register (HLR)
Database containing subscriber information and current location
Target for subscriber data theft and location tracking attacks
Mobile Switching Center (MSC)
Handles call setup, routing, and subscriber mobility
Vulnerable to call interception and service disruption attacks
SS7 Firewall
Security control for filtering malicious SS7 messages
Critical defensive measure for protecting the SS7 network
SS7 Security Architecture
Key Security Controls
SS7 Firewall
Filters malicious SS7 messages based on message type, origin, and content
SMS Home Routing
Prevents direct access to HLR by routing all SMS through the home network
Monitoring Systems
Detect and alert on suspicious SS7 activity in real-time
Common SS7 Attack Vectors
Key Techniques:
- SendRoutingInfoForSM Attack
- AnyTimeInterrogation Attack
- ProvideSubscriberInfo Attack
- + 1 more techniques
Key Techniques:
- UpdateLocation Attack
- InsertSubscriberData Attack
- SendRoutingInfo + Call Forwarding
Real-World Impact of SS7 Vulnerabilities
In 2017, attackers exploited SS7 vulnerabilities to intercept SMS-based two-factor authentication codes sent to German bank customers. This allowed them to bypass security measures and drain accounts.
SMS interception through SS7 network to capture one-time passwords
Law enforcement agencies and private companies have used SS7 vulnerabilities to track individuals' locations without judicial oversight, raising serious privacy concerns.
Location tracking through SendRoutingInfoForSM and AnyTimeInterrogation operations
Critical Infrastructure Implications
SS7 vulnerabilities can impact critical infrastructure that relies on mobile networks for operations, including power grids, water systems, and emergency services. Attackers could potentially disrupt service or intercept sensitive communications during emergencies.
SS7 Exploitation Techniques
SS7 Defensive Strategies
Deploy specialized SS7 firewalls that can filter malicious messages based on origin, message type, and content patterns.
Blocks unauthorized location tracking, SMS interception, and call forwarding attacks
Implement SMS home routing to ensure all SMS messages are routed through the home network, preventing direct access to the HLR.
Prevents SMS interception and subscriber data theft via SendRoutingInfoForSM
Deploy real-time monitoring systems to detect and alert on suspicious SS7 activity patterns indicative of attacks.
Early detection of attack attempts, enabling rapid response and mitigation
Comprehensive Defense Strategy
Effective SS7 security requires a multi-layered approach combining technical controls, operational procedures, and industry collaboration:
- Technical Controls: SS7 firewalls, SMS home routing, monitoring systems, and category-based filtering
- Operational Procedures: Regular security assessments, incident response planning, and staff training
- Industry Collaboration: Information sharing about threats, adherence to GSMA security guidelines, and participation in security working groups
- Evolution: Migration to more secure protocols like Diameter with proper security controls and eventual transition to 5G networks
Related Security Topics
SS7 Security Tools & Resources
SigPloit
Open-source SS7/Diameter/GTP security testing framework
SS7 Pentesting Toolkit
Commercial toolkit for comprehensive SS7 security assessment
Wireshark with SS7 Plugins
Network protocol analyzer with SS7 protocol support
GSMA FS.11
SS7 Interconnect Security Monitoring and Firewall Guidelines
GSMA FS.07
SS7 and SIGTRAN Network Security Guidelines
ITU-T Q.700 Series
Official SS7 protocol specifications
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