CVE-2023-45840
📋 TL;DR
This vulnerability allows attackers to execute arbitrary commands on Buildroot systems through man-in-the-middle attacks targeting package downloads. Attackers can exploit weak package hash checking in the riscv64-elf-toolchain package to inject malicious code during the build process. This affects Buildroot users who download packages from untrusted networks or compromised repositories.
💻 Affected Systems
- Buildroot
📦 What is this software?
Buildroot by Buildroot
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with attacker gaining root privileges on the build system, potentially leading to supply chain attacks where malicious code is embedded in final firmware/images.
Likely Case
Remote code execution on build servers during package download, allowing attackers to steal credentials, modify build artifacts, or pivot to other systems.
If Mitigated
No impact if packages are downloaded from trusted sources over secure connections with proper hash verification.
🎯 Exploit Status
Requires man-in-the-middle position on network traffic between Buildroot and package repository. No authentication needed to trigger the vulnerable code path.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Buildroot 2023.08.2 or later
Vendor Advisory: https://buildroot.org/downloads/CHANGES
Restart Required: No
Instructions:
1. Update Buildroot to version 2023.08.2 or later. 2. Clean and rebuild affected packages: 'make clean' followed by 'make'. 3. Verify package hashes are properly checked during subsequent builds.
🔧 Temporary Workarounds
Use local package mirror with verified hashes
linuxDownload packages to a local, trusted mirror and configure Buildroot to use only local sources with pre-verified hashes.
mkdir -p ~/buildroot-mirror
cd ~/buildroot-mirror
wget --no-check-certificate [package-url] && sha256sum [package-file] > [package-file].sha256
Disable affected package
linuxTemporarily disable the riscv64-elf-toolchain package if not required for your build.
make menuconfig
Navigate to Toolchain -> Toolchain type and select different toolchain
🧯 If You Can't Patch
- Isolate build systems on segmented network with strict egress filtering
- Implement certificate pinning and TLS verification for all external package downloads
🔍 How to Verify
Check if Vulnerable:
Check Buildroot version: 'grep BR2_VERSION ~/buildroot/.config' or examine the CHANGES file. If version is 2023.08.1 or includes commit 622698d7847, system is vulnerable.Check Version:
grep 'BR2_VERSION' $(find . -name .config) || cat Makefile | grep '^VERSION'Verify Fix Applied:
After updating, verify package downloads show proper hash checking: 'make V=1' should show hash verification steps during package download.📡 Detection & Monitoring
Log Indicators:
- Failed hash verification warnings in build logs
- Unexpected network connections during package downloads
- Build process downloading from unexpected sources
Network Indicators:
- Unencrypted HTTP traffic to package repositories
- DNS spoofing attempts targeting buildroot.org or package mirrors
- Unexpected outbound connections during build process
SIEM Query:
source="buildroot.log" AND ("hash mismatch" OR "verification failed" OR "download from")🔗 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
