CVE-2020-21813
📋 TL;DR
CVE-2020-21813 is a heap-based buffer overflow vulnerability in GNU LibreDWG's dwg2SVG converter. Attackers can exploit this by crafting malicious DWG files to execute arbitrary code or crash applications. Users and systems processing DWG files with vulnerable LibreDWG versions are affected.
💻 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.
If Mitigated
Limited to denial of service if memory protections like ASLR are enabled and exploitation fails.
🎯 Exploit Status
Exploitation requires crafting a malicious DWG file; public proof-of-concept code exists in GitHub issue #182.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 0.10.2642 or later
Vendor Advisory: https://github.com/LibreDWG/libredwg/issues/182
Restart Required: No
Instructions:
1. Update LibreDWG to version 0.10.2642 or later. 2. On Linux: Use package manager (e.g., apt-get update && apt-get upgrade libredwg). 3. On Windows/macOS: Download and install the latest version from the official website.
🔧 Temporary Workarounds
Disable dwg2SVG processing
linuxTemporarily disable or restrict use of the dwg2SVG converter in LibreDWG.
# Remove or rename the dwg2SVG binary
sudo mv /usr/bin/dwg2SVG /usr/bin/dwg2SVG.disabled
Input validation for DWG files
allImplement strict validation or sandboxing for DWG file processing.
🧯 If You Can't Patch
- Restrict file uploads to trusted sources only for DWG files.
- Use alternative DWG processing tools that are not vulnerable.
🔍 How to Verify
Check if Vulnerable:
Check LibreDWG version: dwgread --version or libredwg --version; if version is 0.10.2641 or earlier, it is vulnerable.Check Version:
dwgread --version 2>/dev/null || libredwg --version 2>/dev/null || echo 'LibreDWG not found'Verify Fix Applied:
After updating, verify version is 0.10.2642 or later using the same command.📡 Detection & Monitoring
Log Indicators:
- Application crashes or segmentation faults in LibreDWG processes.
- Unusual file processing errors related to DWG files.
Network Indicators:
- Unusual uploads of DWG files to web applications or servers.
SIEM Query:
source="*libredwg*" AND (event_type="crash" OR error="segmentation fault")