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Authentication Attacks

SIM Lock Bypass

MEDIUM

Circumvention of carrier SIM locks that restrict devices to specific network operators, enabling use of unauthorized SIM cards and bypassing carrier restrictions.

Technical Overview

SIM locks are implemented through software restrictions in the baseband processor or operating system. Bypass techniques include unlock code generation, baseband firmware modification, software unlocking tools, or exploiting vulnerabilities in the lock implementation.

Impact
Potential consequences of successful exploitation
  • Bypass of carrier restrictions
  • Unauthorized network access
  • Warranty voiding
  • Revenue loss for carriers
  • Enabling of stolen device markets
Attack Vectors
Methods used to execute this attack
  • Unlock code generation and entry
  • Baseband firmware modification
  • Software-based unlocking tools
  • IMEI-based unlock services
  • Exploiting carrier unlock policies
Attack Methodology
Step-by-step attack execution process
  1. 1Identify device model and carrier lock type
  2. 2Obtain unlock code through calculation or service
  3. 3Enter unlock code or use software tool
  4. 4Modify baseband if software unlock fails
  5. 5Verify unlock with different carrier SIM
  6. 6Test device functionality across networks
Mitigations & Defense
Recommended security measures and countermeasures
  • Implement hardware-backed SIM lock
  • Use secure unlock code generation
  • Deploy tamper-evident lock mechanisms
  • Monitor for unauthorized unlock attempts
  • Implement remote lock/unlock capabilities
  • Regular security updates to lock implementation
Real-World Examples
Documented cases and practical scenarios
  • Third-party unlock services
  • Software unlock tools for popular devices
  • Carrier unlock policy exploitation
  • International phone unlocking markets
  • Stolen device unlocking for resale

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