CVE-2020-37167
📋 TL;DR
CVE-2020-37167 is a critical vulnerability in ClamAV's bytecode interpreter that allows attackers to manipulate function names through weak input validation. This could enable execution of malicious bytecode or cause unexpected behavior in the ClamAV antivirus engine. All systems running vulnerable versions of ClamAV are affected.
💻 Affected Systems
- ClamAV
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution with SYSTEM/root privileges, allowing complete compromise of the affected system and potential lateral movement within the network.
Likely Case
Denial of service through antivirus engine crashes, potentially disrupting malware scanning and email filtering services.
If Mitigated
Limited impact with proper network segmentation and restricted access to ClamAV services, though antivirus functionality may still be disrupted.
🎯 Exploit Status
Exploit code is publicly available and the vulnerability requires minimal technical skill to exploit.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 0.102.3 and later
Vendor Advisory: https://blog.clamav.net/2020/02/clamav-01023-security-patch-released.html
Restart Required: Yes
Instructions:
1. Download ClamAV 0.102.3 or later from clamav.net. 2. Stop ClamAV services. 3. Install the updated version. 4. Update virus definitions. 5. Restart ClamAV services.
🔧 Temporary Workarounds
Disable bytecode interpreter
allTemporarily disable the ClamBC bytecode interpreter to prevent exploitation
clamconf --get Bytecode
clamconf --set Bytecode no
🧯 If You Can't Patch
- Implement strict network segmentation to isolate ClamAV servers from critical systems
- Deploy additional security controls like file integrity monitoring and intrusion detection systems
🔍 How to Verify
Check if Vulnerable:
Run 'clamscan --version' and check if version is below 0.102.3Check Version:
clamscan --version | head -1Verify Fix Applied:
Run 'clamscan --version' and confirm version is 0.102.3 or higher📡 Detection & Monitoring
Log Indicators:
- ClamAV service crashes
- Unexpected bytecode execution errors
- High CPU/memory usage by clamd
Network Indicators:
- Unusual outbound connections from ClamAV servers
- Suspicious file uploads to systems running ClamAV
SIEM Query:
source="clamav" AND (event="crash" OR event="error" OR event="bytecode")