SS7-Based SIM Location Tracking (2021)
High SeverityLarge-scale location tracking operation exploiting SS7 protocol vulnerabilities to track SIM card locations globally, demonstrating the intersection of network and SIM security vulnerabilities.
Overview
In June 2021, security researchers and journalists exposed a large-scale commercial surveillance operation that exploited SS7 protocol vulnerabilities to track the real-time locations of mobile subscribers globally. The operation demonstrated how network-level vulnerabilities could be combined with SIM card location update procedures to enable unauthorized surveillance.
Background
- Discovered through telecommunications security monitoring and whistleblower reports revealing commercial surveillance services
- Commercial surveillance companies were offering location tracking services to government and private entities
- Global operation affecting subscribers across multiple countries and mobile network operators
- Services operated with minimal oversight and questionable legal authorization
Scope of Operations
Geographic Reach
Operations spanned multiple continents with capability to track subscribers in virtually any country with SS7 connectivity
Target Selection
Targeted tracking of specific individuals including journalists, activists, business executives, and government officials
Service Model
Commercial services offered on subscription basis with real-time location tracking dashboards
Detection Evasion
Sophisticated techniques to avoid detection by network security monitoring systems
Technical Details
Attack Vector
SS7 Send Routing Info for Location (SRI-LCS) Messages
Attackers exploited the SRI-LCS message type in SS7 protocol to query the location of target subscribers without proper authorization
Attack Methodology
1. Target Identification
Attackers obtained IMSI (International Mobile Subscriber Identity) and MSISDN (phone number) of target subscribers through various means including data breaches and social engineering
2. SS7 Network Access
Gained access to SS7 network through compromised telecom infrastructure, rogue network operators, or commercial SS7 gateway services
3. Location Query Execution
Sent SRI-LCS messages to target subscriber's home network requesting current location information
4. Location Data Extraction
Received responses containing cell tower information providing location accuracy to within hundreds of meters
5. Continuous Monitoring
Repeated queries at regular intervals to track subscriber movements in real-time
SIM Card Interaction
The attack exploited how SIM cards interact with the network during location updates:
- SIM cards periodically update their location with the network (Location Update procedure)
- Network maintains current location information for routing calls and messages
- SS7 protocol allows authorized entities to query this location information
- Attackers exploited weak authentication in SS7 to pose as authorized entities
- SIM card's IMSI used as primary identifier for location queries
Stealth Mechanisms
Query Rate Limiting
Carefully controlled query frequency to avoid triggering anomaly detection systems
Source Obfuscation
Used multiple SS7 entry points and varied source addresses to complicate tracking
Legitimate Traffic Mimicry
Crafted messages to resemble legitimate inter-operator location queries
Timing Optimization
Scheduled queries during high-traffic periods to blend with normal network activity
Timeline
Operation Initiation
Commercial surveillance services begin offering SS7-based location tracking capabilities to government and private sector clients
Impact: Initial deployment of tracking infrastructure
Scale Expansion
Services expand to cover multiple countries and mobile network operators, with increasing number of targets under surveillance
Impact: Thousands of individuals tracked across multiple continents
Public Exposure
Security researchers and investigative journalists expose the operations through coordinated reporting and technical analysis
Impact: Global awareness of commercial surveillance capabilities
Industry Response
Mobile network operators implement enhanced SS7 filtering and monitoring in response to public disclosure
Impact: Significant reduction in unauthorized location tracking
Impact Assessment
Privacy Impact
Location Exposure
Unauthorized tracking of millions of mobile subscribers without their knowledge or consent
Surveillance Capability
Real-time location monitoring capabilities without legal authorization or oversight
Data Commercialization
Location data sold to commercial and government entities for various purposes
Movement Patterns
Detailed tracking of daily routines, travel patterns, and personal associations
Security Impact
Protocol Vulnerabilities
Demonstrated ongoing SS7 security weaknesses despite years of known vulnerabilities and industry awareness
SIM Security
Highlighted how SIM card identifiers and location update procedures are integral to tracking vulnerabilities
Network Security
Revealed significant gaps in network security monitoring and anomaly detection capabilities
Regulatory Impact
Compliance Violations
Potential violations of GDPR, CCPA, and other privacy regulations
Law Enforcement
Multiple investigations into unauthorized surveillance activities
Policy Implications
Calls for enhanced telecommunications security regulations
Lessons Learned & Prevention
Key Lessons
SS7 vulnerabilities continue to pose significant privacy risks despite years of awareness
SIM cards are integral components of location tracking vulnerabilities through their network interaction
Need for enhanced monitoring of signaling traffic to detect unauthorized location queries
Importance of privacy-by-design principles in telecommunications infrastructure
Critical need for international cooperation on telecommunications security standards
Commercial surveillance services operate with minimal oversight and accountability
Legacy protocol security issues persist due to slow industry migration
Preventive Measures
Network Level
Implement Comprehensive SS7 Firewalls
Deploy advanced SS7 firewalls with deep packet inspection and behavioral analysis
- Filter unauthorized location query messages
- Validate source addresses and routing information
- Implement rate limiting for location requests
Enhanced Location Request Authentication
Strengthen authentication requirements for location service requests
- Implement mutual authentication between networks
- Use cryptographic verification for location queries
- Maintain whitelist of authorized location service providers
Migration to Secure Protocols
Accelerate migration from SS7 to more secure signaling protocols
- Deploy Diameter protocol with enhanced security
- Implement 5G security architecture
- Use IPsec for signaling traffic encryption
Operator Level
Enhanced Monitoring Systems
Deploy comprehensive monitoring for suspicious signaling activity
- Real-time anomaly detection for location queries
- Behavioral analysis of signaling patterns
- Automated alerting for suspicious activity
Privacy Protection Mechanisms
Implement privacy-preserving location technologies
- Location obfuscation for sensitive subscribers
- Subscriber consent mechanisms for location sharing
- Privacy-preserving location update procedures
Regular Security Audits
Conduct comprehensive security assessments of signaling infrastructure
- Penetration testing of SS7 security controls
- Vulnerability assessments of location services
- Third-party security audits
User Level
Use Privacy-Enhancing Technologies
Employ tools and services that enhance location privacy
- Use VPN services for data connections
- Enable airplane mode when location privacy is critical
- Consider using privacy-focused mobile services
Awareness and Vigilance
Stay informed about location tracking risks and indicators
- Monitor for unusual device behavior
- Be aware of high-risk situations and locations
- Report suspicious activity to carrier
Operational Security Practices
Implement operational security measures for sensitive communications
- Use separate devices for sensitive activities
- Employ end-to-end encrypted communications
- Consider using burner phones for high-risk situations