CVE-2020-28624
📋 TL;DR
This vulnerability in CGAL library allows remote code execution through specially crafted polygon files. Attackers can exploit out-of-bounds read and type confusion vulnerabilities in Nef polygon parsing to execute arbitrary code. Systems using CGAL for computational geometry operations are affected.
💻 Affected Systems
- CGAL (Computational Geometry Algorithms Library)
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with attacker gaining code execution at the privilege level of the CGAL process, potentially leading to data theft, ransomware deployment, or lateral movement.
Likely Case
Application crash (denial of service) or limited code execution within the application context, potentially allowing file system access or further exploitation.
If Mitigated
Application crash with no code execution if memory protections (ASLR, DEP) are effective, but still causing service disruption.
🎯 Exploit Status
Exploitation requires crafting specific polygon files and understanding CGAL's internal data structures. No public exploit code has been released.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: CGAL-5.1.2 and later
Vendor Advisory: https://www.cgal.org/
Restart Required: Yes
Instructions:
1. Update CGAL to version 5.1.2 or later. 2. Recompile any applications using CGAL. 3. Restart affected services. 4. For Linux distributions, use package manager: 'sudo apt update && sudo apt upgrade libcgal-dev' (Debian/Ubuntu) or 'sudo yum update CGAL' (RHEL/CentOS).
🔧 Temporary Workarounds
Disable Nef polygon parsing
allModify applications to avoid using CGAL's Nef polygon functionality if not required
Recompile applications with NEF_2/3 support disabled if possible
Input validation
allImplement strict validation of polygon files before passing to CGAL
Add file format validation in application code
🧯 If You Can't Patch
- Network segmentation: Isolate systems using CGAL from untrusted networks
- Application sandboxing: Run CGAL applications in containers or with reduced privileges
🔍 How to Verify
Check if Vulnerable:
Check CGAL version: 'pkg-config --modversion cgal' or check installed packages for libcgal versionCheck Version:
pkg-config --modversion cgal || dpkg -l | grep libcgal || rpm -qa | grep -i cgalVerify Fix Applied:
Verify CGAL version is 5.1.2 or later and applications have been recompiled📡 Detection & Monitoring
Log Indicators:
- Application crashes when processing polygon files
- Memory access violation errors in application logs
- Unexpected process termination of CGAL applications
Network Indicators:
- Unusual file uploads to services processing geometry data
- Multiple failed polygon file processing attempts
SIEM Query:
Process: (name="*cgal*" OR name="*geometry*") AND EventID: (1000 OR 1001) AND Message: ("access violation" OR "segmentation fault" OR "out of bounds")🔗 References
- https://lists.debian.org/debian-lts-announce/2022/12/msg00011.html
- https://security.gentoo.org/glsa/202305-34
- https://talosintelligence.com/vulnerability_reports/TALOS-2020-1225
- https://lists.debian.org/debian-lts-announce/2022/12/msg00011.html
- https://security.gentoo.org/glsa/202305-34
- https://talosintelligence.com/vulnerability_reports/TALOS-2020-1225
