2G Hacking - GSM Network Security
Comprehensive analysis of 2G GSM network security vulnerabilities, including weak encryption, lack of mutual authentication, and protocol weaknesses that enable interception, tracking, and surveillance attacks.
2G Attack Overview
Comprehensive visualization of all 2G GSM network attack vectors organized by severity and category.
2G GSM Network Architecture
Detailed 2G GSM network components, interfaces, and attack surfaces showing where security vulnerabilities exist.
2G Security Weaknesses
Visualization of encryption, authentication, and protocol vulnerabilities in 2G networks.
Critical 2G Attack Vectors
IMSI catchers are rogue base stations that trick mobile devices into connecting to them, allowing attackers to capture International Mobile Subscriber Identity (IMSI) numbers and intercept communications.
Impact:
- Subscriber identification and tracking
- Call and SMS interception
- Location tracking in real-time
- Man-in-the-middle attacks
Mitigation:
Use IMSI catcher detection apps (SnoopSnitch, Android IMSI-Catcher Detector), Enable LTE-only mode to prevent 2G downgrade.
A5/1 is the encryption algorithm used in 2G GSM networks. Due to its weak 64-bit key and known vulnerabilities, it can be broken in real-time to decrypt voice calls and SMS messages.
Impact:
- Complete decryption of voice calls
- SMS message interception and decryption
- Loss of communication confidentiality
- Exposure of sensitive personal and business information
Mitigation:
Upgrade to 3G/4G networks with stronger encryption, Disable 2G on devices when not needed.
Fake Base Transceiver Station (BTS) attacks involve deploying rogue cell towers that impersonate legitimate network infrastructure to intercept communications and perform man-in-the-middle attacks.
Impact:
- Complete interception of voice and data
- Man-in-the-middle attacks on all communications
- Injection of malicious SMS or data
- Denial of service to targeted devices
Mitigation:
Use IMSI catcher detection applications, Monitor for unexpected network changes.
SMS interception attacks allow attackers to capture, read, and potentially modify text messages sent between mobile devices, compromising the confidentiality and integrity of SMS communications.
Impact:
- Exposure of sensitive personal communications
- 2FA/OTP bypass for account takeover
- Business intelligence gathering
- Privacy violations and surveillance
Mitigation:
Use end-to-end encrypted messaging apps instead of SMS, Implement app-based 2FA instead of SMS OTP.
Call interception attacks enable attackers to eavesdrop on voice communications by capturing and decrypting the audio stream between mobile devices and the network.
Impact:
- Complete loss of voice communication privacy
- Exposure of confidential business discussions
- Personal privacy violations
- Intelligence gathering and espionage
Mitigation:
Use encrypted VoIP applications (Signal, WhatsApp calls), Upgrade to 4G/5G with stronger encryption.
Downgrade attacks force mobile devices to connect to older, less secure network technologies (2G) where encryption is weaker and easier to break, enabling various attack vectors.
Impact:
- Exposure to weak 2G encryption
- Vulnerability to IMSI catcher attacks
- Increased susceptibility to interception
- Bypass of modern security features
Mitigation:
Disable 2G in device settings (LTE-only mode), Use network selection to prefer 4G/5G.
Key 2G Vulnerabilities
The A5/1 stream cipher uses only 64-bit keys and can be broken in real-time using rainbow tables. Designed in 1987, it has been cryptographically broken since 2009.
- Real-time decryption possible
- Rainbow table attacks effective
- No forward secrecy
Devices authenticate to the network, but the network does not authenticate to devices. This allows fake base stations to impersonate legitimate networks.
- Devices trust any base station
- Enables IMSI catcher attacks
- No certificate validation
International Mobile Subscriber Identity is transmitted in plaintext during initial attach, enabling passive tracking and identification.
- No identity protection
- Passive tracking possible
- No temporary identifiers
2G protocols lack message integrity protection, enabling replay attacks and message modification without detection.
- No message authentication
- Replay attacks possible
- Downgrade vulnerabilities
2G Security Best Practices
For Mobile Operators
- •Deploy 2G sunset policies and migrate subscribers to 4G/5G networks
- •Implement network-level IMSI catcher detection systems
- •Deploy SUPI/SUCI protection in 5G networks
- •Monitor for forced downgrade attacks and rogue base stations
- •Implement anomaly detection for unusual network behavior
For End Users
- •Disable 2G in device settings (LTE-only mode) when possible
- •Use IMSI catcher detection apps (SnoopSnitch, AIMSICD)
- •Use encrypted communication apps (Signal, WhatsApp) instead of SMS/voice
- •Monitor for unusual network behavior and signal anomalies
- •Use app-based 2FA instead of SMS OTP when available