Telco Security
Back to Mobile Attacks
4G/LTE Attacks

IMSI Extraction

HIGH SEVERITY
Overview

Despite 4G LTE's improved security, IMSI extraction attacks exploit vulnerabilities in the attach procedure to capture subscriber identities before encryption is established.

Technical Overview

LTE networks use temporary identifiers (GUTI) to protect IMSI, but during initial attach or after GUTI expiration, devices must transmit IMSI in cleartext. Attackers use rogue eNodeBs to trigger identity requests and capture IMSI values.

Impact
Potential consequences of this attack
  • •Subscriber identification and tracking
  • •Privacy violations through identity exposure
  • •Enabling of targeted attacks
  • •Location tracking capabilities
  • •Correlation with other data sources
Attack Vectors
Methods used to execute this attack
  • •Rogue eNodeB deployment to trigger identity requests
  • •Paging message manipulation to force IMSI transmission
  • •GUTI reallocation attacks
  • •Exploiting attach procedure vulnerabilities
  • •Passive monitoring during initial attach
Attack Methodology
Step-by-step attack execution process
  1. 1Deploy rogue eNodeB with legitimate-looking parameters
  2. 2Broadcast to attract device connections
  3. 3Send identity request messages
  4. 4Capture IMSI from device response
  5. 5Optionally release device to legitimate network
  6. 6Build database of IMSI-location mappings
Mitigations & Defense
Protective measures and countermeasures
  • Implement SUPI/SUCI protection (5G feature)
  • Use IMSI encryption at network level
  • Deploy rogue base station detection
  • Monitor for unusual identity request patterns
  • Implement enhanced privacy features in devices
  • Use network-level anomaly detection
Real-World Examples
Known incidents and use cases
  • →Research demonstrations at security conferences
  • →Law enforcement surveillance operations
  • →Privacy violations in public spaces
  • →Targeted tracking of individuals
  • →Mass surveillance at events

Related Attacks

4G/LTE Attacks
Rogue eNodeB

Rogue eNodeB attacks involve deploying fake LTE base stations that impersonate legitimate network infrastructure to intercept communications and perform man-in-the-middle attacks.

4G/LTE Attacks
MitM Attacks

Man-in-the-Middle attacks on LTE networks position the attacker between the device and legitimate network infrastructure to intercept, monitor, and manipulate communications.

4G/LTE Attacks
Location Tracking

Location tracking attacks exploit LTE protocols and network architecture to determine the physical location of mobile devices without user consent or awareness.

References & Further Reading