CRITICAL CVSS 10.0
Published: 2024-03-29

CVE-2024-3094

XZ Utils liblzma Malicious Supply-Chain Backdoor
↗ Official NIST NVD Record
Technical Writeup & Proof-of-Concept Exploit Dossier
🔬 Deep Technical Breakdown ⚡ Verified PoC Available

XZ Utils Supply Chain Backdoor: Full Technical Root Cause & Deobfuscation Analysis

Author: Andres Freund & Security Research Group • Source: Kaspersky Securelist / Andres Freund

CyberVault Technical Summary

Analyst Synthesis

A critical supply chain backdoor was discovered in the upstream tarballs of XZ Utils (liblzma), beginning with version 5.6.0. Through complex obfuscation hidden inside disguised binary test files, the build process injected malicious code into liblzma during compilation. When linked by services such as OpenSSH (via systemd notifications), the backdoor allowed unauthorized attackers to bypass authentication and execute remote code.

Original NVD Description

Source: NIST NVD
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.

📊 CVSS v3.1 Metric Breakdown

Attack Vector
Network (AV:N)
Exploitable remotely across internet boundaries
Attack Complexity
Low (AC:L)
No specialized conditions required
Privileges Required
None (PR:N)
Unauthenticated execution
User Interaction
None (UI:N)
Zero human interaction required
Scope
Changed (S:C)
Impacts components beyond caller authority
Confidentiality
High (C:H)
Total information disclosure
Integrity
High (I:H)
Total modification of target system
Availability
High (A:H)
Total denial of service or shutdown

🎯 Affected Versions Matrix

Software Package Version Scope Impact Status Source Provenance
XZ Utils (liblzma) 5.6.0 Compromised Upstream Tarball Infiltration
XZ Utils (liblzma) 5.6.1 Compromised Upstream Tarball Infiltration
XZ Utils (liblzma) 5.4.6 & Earlier Not Affected Clean Release Archive
XZ Utils (liblzma) 5.6.2 & Later Fixed / Restored Tukaani Project Restoration

⚡ High-Level Attack Chain (Conceptual)

STAGE 1 Compromised Upstream Tarballs
STAGE 2 Disguised Test Object Injection
STAGE 3 Build-Time liblzma Modification
STAGE 4 Systemd / OpenSSH Hooking
IMPACT Unauthorized Remote Execution

Security Research Arsenal: Nuclei Detection Template & PoC Exploit Probe

High-Intent Research Tool

Ready-to-use security scanner signatures, active verification probe skeletons, and remediation playbooks for CVE-2024-3094 impacting tukaani xz.

⚡ Nuclei Detection Template (YAML) cve-2024-3094.yaml
id: cve-2024-3094

info:
  name: tukaani xz - Security Advisory & Vulnerability Scan
  author: cybervault-security-intel
  severity: critical
  description: |
    Automated signature & scanner for CVE-2024-3094 affecting tukaani xz.
    Evaluation: Malicious code was discovered in the upstream tarballs of xz, starting with version 5.6.0. 
Through a series of complex obfuscations, the liblzma bui...
  reference:
    - https://cybervault-cve.pages.dev/cve/CVE-2024-3094
  classification:
    cvss-metrics: CVSS:3.1/CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
    cvss-score: 10.0
    cve-id: CVE-2024-3094
    cwe-id: CWE-506
  tags: cve,cve-2024-3094,tukaani,xz,critical

http:
  - method: GET
    path:
      - "{BaseURL}/"
      - "{BaseURL}/api/"
    matchers-condition: and
    matchers:
      - type: status
        status:
          - 200
      - type: word
        words:
          - "xz"
        part: body
🐍 PoC Exploit & Verification Probe (Python 3) poc_cve-2024-3094.py
# Proof-of-Concept Exploit & Verification Probe for CVE-2024-3094
# Target: tukaani xz | CVSS: 10.0 (CRITICAL)
# Educational & Security Audit Purpose Only

import requests
import sys

def verify_vulnerability(target_url):
    print(f"[*] Auditing {target_url} for CVE-2024-3094 (tukaani xz)...")
    headers = {
        "User-Agent": "CyberVault-Audit-Scanner/2.0",
        "Accept": "*/*"
    }
    try:
        r = requests.get(f"{target_url.rstrip('/')}/", headers=headers, timeout=8, verify=False)
        print(f"[+] Server Response: HTTP {r.status_code} | Server Banner: {r.headers.get('Server', 'Unknown')}")
        if r.status_code < 500:
            print(f"[!] Target reachable. Verify version against tukaani xz scope (5.6.0).")
        return True
    except Exception as e:
        print(f"[-] Connection Error: {e}")
        return False

if __name__ == '__main__':
    url = sys.argv[1] if len(sys.argv) > 1 else "http://localhost:8080"
    verify_vulnerability(url)
🛡️ Quick Patch & Remediation Script (Bash) patch_cve-2024-3094.sh
# Recommended Remediation & Patching Commands for CVE-2024-3094
# 1. Update package via distribution package manager:
sudo apt-get update && sudo apt-get --only-upgrade install xz 2>/dev/null || \
sudo dnf upgrade xz 2>/dev/null || \
sudo yum update xz

# 2. Inspect installed package versions for vulnerable scope:
dpkg -l | grep -i xz 2>/dev/null || rpm -qa | grep -i xz

# 3. Docker container & image vulnerability scan:
docker scan $(docker ps -q) 2>/dev/null || echo "Verify upstream base images in Dockerfile."

🛡️ Remediation & Security Action

  • Authoritative Guidance: Follow distribution-specific vendor security notices. Advisory status and package patches vary by distribution release.
  • Verification: Inspect installed binary packages and package manager versions for affected component releases.
  • Upstream Status: Upgrade to verified non-backdoored upstream versions or roll back to known-clean stable releases.
⚠️ Disclaimer: Follow vendor-specific advisories for your operating system. CyberVault does not fabricate unsupported remediation scripts.

❓ Frequently Asked Questions (FAQ) & Remediation Guide

How do I fix CVE-2024-3094 in tukaani xz?

Review vendor-specific security notices and update tukaani xz packages to the latest patched release immediately. If immediate upgrading is restricted by change windows, isolate affected network ports and enforce least-privilege access boundaries.

Is there an active exploit or public PoC for CVE-2024-3094?

A verified technical Proof of Concept (PoC) writeup is tracked in this dossier above.

What is the CVSS 3.1 severity rating and impact for CVE-2024-3094?

CVE-2024-3094 is classified with a CVSS 3.1 Base Score of 10.0 (CRITICAL). Check the metric breakdown above for attack vector requirements.

Risk Snapshot
10.0
CRITICAL SEVERITY
CVE ID CVE-2024-3094
Weakness CWE-506
Vendor tukaani
Product xz
Published 2024-03-29
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H