CVE-2024-3094: Tukaani Xz Backdoor RCE Vulnerability

CVE-2024-3094 Overview

Malicious code was discovered in the upstream tarballs of xz, starting with version 5.6.0. Through a series of complex obfuscations, the liblzma build process extracts a prebuilt object file from a disguised test file existing in the source code, which is then used to modify specific functions in the liblzma code. This results in a modified liblzma library that can be used by any software linked against this library, intercepting and modifying the data interaction with this library.

Critical Impact

This vulnerability allows for unauthorized code execution and data manipulation, significantly compromising data integrity and system security.

Affected Products

• tukaani xz 5.6.0
• tukaani xz 5.6.1

Discovery Timeline

• Not Available - Vulnerability discovered by Not Available
• Not Available - Responsible disclosure to tukaani
• Not Available - CVE CVE-2024-3094 assigned
• Not Available - tukaani releases security patch
• 2024-03-29 - CVE CVE-2024-3094 published to NVD
• 2025-08-19 - Last updated in NVD database

Technical Details for CVE-2024-3094

Vulnerability Analysis

The malicious code embedded within the xz utility leverages complex obfuscation techniques to extract a prebuilt object file, which is subsequently used to alter key functions within the liblzma library. This manipulation can be exploited to modify data interactions, posing a high risk of unauthorized code execution.

Root Cause

The root cause lies in the inclusion of obfuscated malicious code within the upstream tarballs starting from version 5.6.0, enabling unauthorized code execution through library function modifications.

Attack Vector

This vulnerability can be exploited remotely over the network, allowing attackers to execute malicious code without requiring prior access or permissions on the target system.

// Simulated exploitation code (sanitized)
#include <stdio.h>

void executeMaliciousCode() {
    // Payload execution
    printf("Malicious Code Executed");
}

int main() {
    // Triggering the backdoor
    executeMaliciousCode();
    return 0;
}

Detection Methods for CVE-2024-3094

Indicators of Compromise

• Unexpected changes in liblzma behavior
• Altered checksum of xz utility binaries
• Anomalous system calls related to liblzma

Detection Strategies

Monitor file integrity of liblzma and xz binaries using hash verification tools. Implement regular scans and behavioral analytics to detect abnormal interactions with the liblzma library.

Monitoring Recommendations

Utilize SentinelOne endpoint protection to track and block unexpected library modifications and to respond to alerts indicating potential tampering occurrences promptly.

How to Mitigate CVE-2024-3094

Immediate Actions Required

• Investigate and replace tainted xz versions with a verified clean build.
• Monitor network traffic for unusual patterns indicating remote exploitation attempts.
• Initiate comprehensive security audits across systems utilizing xz versions 5.6.0 and 5.6.1.

Patch Information

Contact tukaani for the latest patches and advisories related to xz, ensuring the replacement of compromised versions immediately.

Workarounds

Until patches are applied, restrict the use of affected xz versions and apply strict file integrity checks on all installations.

# Configuration example
apt-get remove xz-utils
# Reinstall from trusted source
apt-get install xz-utils --allow-unauthenticated