CVE-2023-45838
📋 TL;DR
This CVE describes multiple data integrity vulnerabilities in Buildroot's package hash checking functionality that allow man-in-the-middle attackers to execute arbitrary commands on the builder system. Attackers can intercept and modify package downloads to inject malicious code. This affects Buildroot users who download packages over untrusted networks.
💻 Affected Systems
- Buildroot
📦 What is this software?
Buildroot by Buildroot
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of the build system leading to supply chain attacks, backdoored firmware/images, and lateral movement to connected systems.
Likely Case
Attackers intercept package downloads to inject malware into builds, compromising the integrity of generated firmware/images.
If Mitigated
Limited impact with proper network segmentation, certificate pinning, and offline build environments.
🎯 Exploit Status
Requires MITM position on network path between Buildroot and package repositories. No public exploit code identified in references.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Buildroot versions after 2023.08.1 with security patches applied
Vendor Advisory: http://www.openwall.com/lists/oss-security/2023/12/11/1
Restart Required: No
Instructions:
1. Update Buildroot to latest version. 2. Apply security patches for hash checking functionality. 3. Rebuild affected packages. 4. Verify package integrity with updated hash checks.
🔧 Temporary Workarounds
Use local package mirror with integrity verification
linuxMaintain a local mirror of required packages with pre-verified hashes to avoid downloading from external sources during builds.
# Configure Buildroot to use local package source
# Set BR2_PRIMARY_SITE to local mirror path
# Pre-download and verify all packages before building
Enforce TLS certificate validation
linuxEnsure Buildroot is configured to validate TLS certificates when downloading packages over HTTPS.
# Verify Buildroot's wget/curl configurations enforce certificate validation
# Check for --no-check-certificate flags and remove them
🧯 If You Can't Patch
- Isolate build systems on segmented networks with strict egress controls
- Implement network monitoring for MITM attacks and unauthorized package modifications
🔍 How to Verify
Check if Vulnerable:
Check Buildroot version: 'make -v' or examine Buildroot directory for version markers. Verify if using affected versions (2023.08.1 or dev commit 622698d7847).Check Version:
grep 'BR2_VERSION' $(find . -name '*.mk' -o -name 'Config.in') 2>/dev/null | head -1Verify Fix Applied:
Verify Buildroot version is updated beyond affected versions. Test package downloads with invalid hashes to ensure they are rejected.📡 Detection & Monitoring
Log Indicators:
- Failed hash checks for packages
- Unexpected package download sources
- Build errors related to package integrity
Network Indicators:
- Unencrypted package downloads
- MITM patterns in network traffic to package repositories
SIEM Query:
source="buildroot.log" AND ("hash mismatch" OR "integrity check failed" OR "package verification")🔗 References
- http://www.openwall.com/lists/oss-security/2023/12/11/1
- https://talosintelligence.com/vulnerability_reports/TALOS-2023-1844
- http://www.openwall.com/lists/oss-security/2023/12/11/1
- https://talosintelligence.com/vulnerability_reports/TALOS-2023-1844
- https://www.talosintelligence.com/vulnerability_reports/TALOS-2023-1844
