CVE-2020-21831
📋 TL;DR
A heap-based buffer overflow vulnerability in GNU LibreDWG 0.10 allows attackers to execute arbitrary code or cause denial of service by processing specially crafted DWG files. This affects any application or service that uses LibreDWG to handle DWG CAD files. Users and systems processing untrusted DWG files are at risk.
💻 Affected Systems
- GNU LibreDWG
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution with the privileges of the LibreDWG process, potentially leading to full system compromise.
Likely Case
Application crash (denial of service) when processing malicious DWG files, with potential for code execution in some scenarios.
If Mitigated
Limited to denial of service if exploit fails or memory protections are in place.
🎯 Exploit Status
Exploitation requires the victim to open a malicious DWG file. Public proof-of-concept exists in GitHub issue #188, making weaponization likely.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Fixed in versions after 0.10; check latest release (e.g., 0.11 or later).
Vendor Advisory: https://github.com/LibreDWG/libredwg/issues/188
Restart Required: No
Instructions:
1. Update LibreDWG to the latest version from the official repository. 2. Recompile any applications using LibreDWG with the updated library. 3. Replace old LibreDWG installations with the patched version.
🔧 Temporary Workarounds
Disable DWG file processing
allTemporarily block or avoid processing DWG files with LibreDWG until patched.
Use alternative DWG libraries
allSwitch to alternative CAD file libraries (e.g., Open Design Alliance) if possible.
🧯 If You Can't Patch
- Restrict DWG file uploads and processing to trusted sources only.
- Run LibreDWG in a sandboxed or isolated environment to limit potential damage.
🔍 How to Verify
Check if Vulnerable:
Check if LibreDWG version is 0.10 or earlier by running 'dwgread --version' or checking library version.Check Version:
dwgread --versionVerify Fix Applied:
Update to the latest version and test with known malicious DWG samples from the GitHub issue to ensure no crash.📡 Detection & Monitoring
Log Indicators:
- Application crashes or segmentation faults when processing DWG files
- Unusual memory usage spikes in LibreDWG processes
Network Indicators:
- Inbound transfers of DWG files to vulnerable services
SIEM Query:
Process: 'dwgread' OR 'libredwg' AND Event: 'Crash' OR 'Segmentation fault'