CVE-2021-40391
📋 TL;DR
This CVE describes a critical out-of-bounds write vulnerability in Gerbv, a Gerber file viewer used in PCB design. Attackers can execute arbitrary code by tricking users into opening specially crafted drill files. Users of Gerbv versions 2.7.0 and certain development commits are affected.
💻 Affected Systems
- Gerbv
📦 What is this software?
Fedora by Fedoraproject
Gerbv by Gerbv Project
Gerbv by Gerbv Project
Gerbv by Gerbv Project
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with remote code execution leading to complete control of the affected system, data theft, or ransomware deployment.
Likely Case
Local privilege escalation or arbitrary code execution when a user opens a malicious drill file, potentially leading to lateral movement within the network.
If Mitigated
Limited impact if file execution is restricted through application sandboxing or user privileges are minimized.
🎯 Exploit Status
Exploitation requires user interaction to open a malicious file. Proof-of-concept details are available in public advisories.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.7.1 or later
Vendor Advisory: https://lists.debian.org/debian-lts-announce/2021/12/msg00003.html
Restart Required: Yes
Instructions:
1. Update Gerbv to version 2.7.1 or later using your package manager. 2. For Linux: Use apt-get update && apt-get upgrade gerbv. 3. For Windows/macOS: Download the latest version from the official repository. 4. Restart the application after update.
🔧 Temporary Workarounds
Restrict file processing
allLimit Gerbv to trusted file sources and avoid opening untrusted drill files.
Run with reduced privileges
linuxExecute Gerbv with minimal user permissions to limit potential damage from exploitation.
sudo -u lowprivilegeuser gerbv
🧯 If You Can't Patch
- Disable or uninstall Gerbv if not essential.
- Implement application whitelisting to block execution of vulnerable Gerbv versions.
🔍 How to Verify
Check if Vulnerable:
Check Gerbv version: gerbv --version. If output shows 2.7.0 or matches affected dev commits, the system is vulnerable.Check Version:
gerbv --versionVerify Fix Applied:
After updating, run gerbv --version to confirm version is 2.7.1 or higher.📡 Detection & Monitoring
Log Indicators:
- Unexpected crashes of Gerbv process
- Unusual file access patterns from Gerbv
Network Indicators:
- Outbound connections from Gerbv to unknown IPs post-exploitation
SIEM Query:
process_name:"gerbv" AND (event_type:"crash" OR file_path:"*.drl")🔗 References
- https://lists.debian.org/debian-lts-announce/2021/12/msg00003.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TUM5GIUZJ7AVHVCXDZW6ZVCAPV2ISN47/
- https://www.talosintelligence.com/vulnerability_reports/TALOS-2021-1402
- https://lists.debian.org/debian-lts-announce/2021/12/msg00003.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TUM5GIUZJ7AVHVCXDZW6ZVCAPV2ISN47/
- https://www.talosintelligence.com/vulnerability_reports/TALOS-2021-1402
