CVE-2023-51636
📋 TL;DR
This vulnerability in Avira Prime allows local attackers to escalate privileges from a low-privileged account to SYSTEM level by exploiting a symbolic link issue in the Avira Spotlight Service. Attackers must first gain execution capability on the target system. All Avira Prime installations with the vulnerable service are affected.
💻 Affected Systems
- Avira Prime
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Full SYSTEM compromise allowing complete control over the system, installation of persistent malware, credential theft, and lateral movement across the network.
Likely Case
Local privilege escalation enabling attackers to bypass security controls, install additional malware, and maintain persistence on compromised systems.
If Mitigated
Limited impact if proper endpoint protection, least privilege principles, and application control are enforced, though the vulnerability still provides escalation path.
🎯 Exploit Status
Exploitation requires local access and ability to create symbolic links. The vulnerability is well-documented in the ZDI advisory.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not specified in available references, but Avira has released updates
Vendor Advisory: https://www.zerodayinitiative.com/advisories/ZDI-24-469/
Restart Required: Yes
Instructions:
1. Open Avira Prime application. 2. Check for updates in settings. 3. Install all available updates. 4. Restart the system to ensure the Avira Spotlight Service is updated.
🔧 Temporary Workarounds
Disable Avira Spotlight Service
windowsTemporarily disable the vulnerable service until patching can be completed
sc stop "Avira Spotlight Service"
sc config "Avira Spotlight Service" start= disabled
Remove symbolic link creation privileges
windowsRestrict ability to create symbolic links for non-administrative users
secedit /export /cfg config.inf
Edit config.inf to set SeCreateSymbolicLinkPrivilege = *S-1-5-32-544
secedit /configure /db config.sdb /cfg config.inf
🧯 If You Can't Patch
- Implement strict least privilege principles to limit initial access opportunities
- Deploy application control solutions to prevent unauthorized code execution
🔍 How to Verify
Check if Vulnerable:
Check Avira Prime version and compare against patched versions. Verify if Avira Spotlight Service is running and vulnerable.Check Version:
Check Avira Prime About section or run: wmic product where "name like 'Avira%'" get versionVerify Fix Applied:
Verify Avira Prime is updated to latest version and check that symbolic link exploitation no longer works.📡 Detection & Monitoring
Log Indicators:
- Unusual symbolic link creation events
- Avira Spotlight Service process manipulation
- Privilege escalation attempts from low-privilege accounts
Network Indicators:
- None - this is a local vulnerability
SIEM Query:
EventID=4688 AND ProcessName="AviraSpotlightService.exe" AND ParentProcess NOT IN ("services.exe", "svchost.exe")