CVE-2022-24401: Tetra Information Disclosure Vulnerability

CVE-2022-24401 Overview

CVE-2022-24401 is a critical cryptographic vulnerability affecting the TETRA (Terrestrial Trunked Radio) air-interface encryption protocol. The vulnerability enables adversary-induced keystream re-use on TETRA air-interface encrypted traffic using any TEA (TETRA Encryption Algorithm) keystream generator. This flaw stems from the IV (Initialization Vector) generation mechanism, which relies on several TDMA (Time Division Multiple Access) frame counters that are frequently broadcast by the infrastructure in an unauthenticated manner.

An active adversary positioned within adjacent network range can manipulate the view of these counters in a mobile station, deliberately provoking keystream re-use. By sending crafted messages to the mobile station and analyzing the responses, an attacker can recover the keystream for arbitrary frames, effectively compromising the confidentiality and integrity of encrypted communications.

Critical Impact

This vulnerability allows attackers to break TETRA encryption by forcing keystream re-use, potentially exposing sensitive communications used by emergency services, military, and critical infrastructure operators worldwide.

Affected Products

• TETRA-enabled mobile stations using TEA keystream generators
• TETRA infrastructure broadcasting unauthenticated TDMA frame counters
• Midnightblue TETRA:BURST research implementation

Discovery Timeline

• 2023-10-19 - CVE CVE-2022-24401 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2022-24401

Vulnerability Analysis

The vulnerability is rooted in a fundamental cryptographic design weakness (CWE-323: Reusing a Nonce, Key Pair in Encryption and CWE-639: Authorization Bypass Through User-Controlled Key). TETRA's air-interface encryption relies on IV generation that incorporates TDMA frame counters. These counters are essential for synchronizing communication between base stations and mobile stations but are broadcast without cryptographic authentication.

The attack exploits this lack of authentication to manipulate the mobile station's perception of the current frame counter values. When an attacker successfully alters these counter values, the mobile station generates IVs that have been used previously, resulting in keystream re-use—a well-known cryptographic failure that can lead to plaintext recovery through XOR operations on ciphertexts encrypted with the same keystream.

Root Cause

The root cause is twofold: first, the TDMA frame counters used in IV generation are broadcast without authentication, allowing an active adversary to spoof or modify these values. Second, the encryption scheme does not implement adequate safeguards against IV reuse, making the system vulnerable to classic stream cipher attacks when keystream repetition occurs.

Attack Vector

This vulnerability requires adjacent network access, meaning the attacker must be within radio range of the target TETRA mobile station. The attack is classified as low complexity and requires no authentication or user interaction. The attacker performs the following steps:

1. Position within radio range of the target mobile station
2. Monitor the infrastructure's broadcast of TDMA frame counters
3. Craft and transmit spoofed frame counter values to the mobile station
4. Send crafted messages to the mobile station to elicit responses
5. Analyze the encrypted responses to recover keystream material
6. Use recovered keystream to decrypt arbitrary frames or forge messages

The attack enables both high confidentiality and integrity impacts, as recovered keystreams can be used to decrypt communications and potentially inject malicious traffic.

Detection Methods for CVE-2022-24401

Indicators of Compromise

• Anomalous TDMA frame counter values that deviate significantly from expected sequences
• Unexpected frame counter resets or jumps within TETRA network traffic
• Increased error rates or synchronization issues in mobile stations
• Detection of duplicate IV values in captured air-interface traffic

Detection Strategies

• Deploy monitoring systems capable of analyzing TETRA air-interface traffic for frame counter anomalies
• Implement baseline analysis of normal frame counter progression to detect manipulation attempts
• Monitor mobile stations for unusual behavior patterns indicating synchronization attacks
• Utilize spectrum analysis tools to detect rogue base station activity in the vicinity

Monitoring Recommendations

• Establish continuous monitoring of TETRA infrastructure for unauthorized broadcast sources
• Log and analyze frame counter sequences across the network for statistical anomalies
• Implement alerting for mobile stations that exhibit signs of frame counter manipulation
• Conduct regular RF surveys to identify potential adversary positioning near critical infrastructure

How to Mitigate CVE-2022-24401

Immediate Actions Required

• Assess exposure of TETRA communications to determine criticality and risk level
• Review deployment configurations and identify mobile stations in high-risk environments
• Consider transitioning sensitive communications to alternative encrypted channels where feasible
• Engage with TETRA equipment vendors for specific guidance and available mitigations

Patch Information

This vulnerability affects the fundamental TETRA protocol design rather than a specific software implementation. Organizations should consult the TetraBurst Security Overview for comprehensive technical details and vendor-specific guidance. Equipment manufacturers may provide firmware updates that implement additional protections or workarounds for this vulnerability.

Workarounds

• Implement end-to-end encryption at the application layer to protect sensitive communications independently of TETRA air-interface encryption
• Deploy RF shielding or directional antennas to reduce the effective range from which an adversary could conduct attacks
• Increase physical security around TETRA infrastructure to limit adversary positioning opportunities
• Consider network segmentation and compartmentalization of sensitive communications

Organizations relying on TETRA for critical communications should conduct a thorough risk assessment and develop migration plans to more robust encryption standards where operational requirements permit. The fundamental nature of this protocol-level vulnerability means complete remediation may require transitioning to updated TETRA standards or alternative communication systems.