CVE-2024-20505
📋 TL;DR
An out-of-bounds read vulnerability in ClamAV's PDF parsing module allows remote attackers to cause denial of service by submitting crafted PDF files. This affects ClamAV scanning processes on devices running vulnerable versions, potentially disrupting antivirus scanning capabilities.
💻 Affected Systems
- Clam AntiVirus (ClamAV)
📦 What is this software?
Clamav by Clamav
Clamav by Clamav
Clamav by Clamav
Clamav by Clamav
⚠️ Risk & Real-World Impact
Worst Case
Complete disruption of ClamAV scanning services, potentially allowing malware to bypass detection while scanning is disabled.
Likely Case
Temporary termination of scanning processes requiring service restart, causing brief gaps in file scanning coverage.
If Mitigated
Minimal impact with proper network segmentation and file upload restrictions preventing malicious PDFs from reaching ClamAV.
🎯 Exploit Status
Exploitation requires submitting a crafted PDF file to be scanned by ClamAV, which is straightforward for attackers with file upload capabilities.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.4.1, 1.3.3, 1.0.7, 0.103.12
Vendor Advisory: https://blog.clamav.net/2024/09/clamav-141-132-107-and-010312-security.html
Restart Required: Yes
Instructions:
1. Download latest patched version from clamav.net 2. Stop ClamAV services 3. Install updated version 4. Update virus definitions 5. Restart ClamAV services
🔧 Temporary Workarounds
Disable PDF scanning
allTemporarily disable PDF file scanning in ClamAV configuration to prevent exploitation
Edit clamd.conf and add: ScanPDF no
Edit freshclam.conf if applicable
Restrict file uploads
allImplement strict file upload validation to block suspicious PDF files before they reach ClamAV
🧯 If You Can't Patch
- Implement network segmentation to isolate ClamAV servers from untrusted networks
- Deploy additional file validation layers before PDFs reach ClamAV scanning
🔍 How to Verify
Check if Vulnerable:
Run: clamscan --version and check if version matches affected rangeCheck Version:
clamscan --version | head -1Verify Fix Applied:
Verify version is 1.4.1, 1.3.3, 1.0.7, or 0.103.12 or higher📡 Detection & Monitoring
Log Indicators:
- ClamAV process crashes
- Scanning service restarts
- Error messages related to PDF parsing
Network Indicators:
- Unusual PDF file uploads to systems using ClamAV
- Multiple failed scan attempts
SIEM Query:
source="clamav" AND ("crash" OR "segfault" OR "out of bounds")