CVE-2021-42585
📋 TL;DR
CVE-2021-42585 is a heap buffer overflow vulnerability in LibreDWG's dwgread library that allows remote code execution when processing malicious DWG files. This affects any application using LibreDWG versions before 0.12.4 to read AutoCAD DWG files. Attackers can exploit this by tricking users into opening specially crafted DWG files.
💻 Affected Systems
- LibreDWG
- Applications using LibreDWG library
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution with the privileges of the application processing the DWG file, potentially leading to full system compromise.
Likely Case
Application crash (denial of service) or limited code execution depending on exploit sophistication and memory protections.
If Mitigated
Application crash with no code execution if ASLR/DEP/stack canaries are properly implemented and effective.
🎯 Exploit Status
Proof of concept exists in the GitHub issue. Exploitation requires crafting a malicious DWG file and getting it processed by vulnerable software.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 0.12.4 and later
Vendor Advisory: https://github.com/LibreDWG/libredwg/issues/351
Restart Required: Yes
Instructions:
1. Update LibreDWG to version 0.12.4 or later. 2. Rebuild any applications using LibreDWG. 3. Restart affected services or applications.
🔧 Temporary Workarounds
Disable DWG file processing
allBlock or restrict processing of DWG files in vulnerable applications
Use alternative DWG viewers
allUse different software for DWG file viewing that doesn't use vulnerable LibreDWG versions
🧯 If You Can't Patch
- Implement strict file upload restrictions for DWG files
- Use application sandboxing or containerization to limit potential damage
🔍 How to Verify
Check if Vulnerable:
Check if LibreDWG version is below 0.12.4 or if applications report using vulnerable dwgread libraryCheck Version:
dwgread --version or check package manager for libredwg versionVerify Fix Applied:
Verify LibreDWG version is 0.12.4 or higher and applications have been rebuilt with updated library📡 Detection & Monitoring
Log Indicators:
- Application crashes when processing DWG files
- Memory access violation errors
- Segmentation faults in dwgread processes
Network Indicators:
- Unusual outbound connections after DWG file processing
- File uploads of DWG files to web applications
SIEM Query:
process_name:dwgread AND (event_type:crash OR memory_violation)