CVE-2021-38465
📋 TL;DR
CVE-2021-38465 is a resource exhaustion vulnerability in Auvesy webinstaller that allows attackers to fill the server's temporary storage by generating excessive installation requests. This affects organizations using Auvesy image agent deployment systems. The vulnerability can lead to denial of service and potentially system crashes.
💻 Affected Systems
- Auvesy webinstaller
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system crash or unavailability of the webinstaller service due to disk space exhaustion, potentially disrupting critical deployment operations.
Likely Case
Degraded performance of the webinstaller service, temporary unavailability, and potential need for manual cleanup of temp files.
If Mitigated
Minimal impact with proper monitoring and disk space management in place.
🎯 Exploit Status
The vulnerability requires no authentication and can be triggered by sending repeated installation generation requests.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check vendor advisory for specific patched versions
Vendor Advisory: https://us-cert.cisa.gov/ics/advisories/icsa-21-292-01
Restart Required: Yes
Instructions:
1. Review ICSA-21-292-01 advisory. 2. Contact Auvesy for patched version. 3. Apply patch to affected webinstaller instances. 4. Restart webinstaller service.
🔧 Temporary Workarounds
Implement rate limiting
allAdd rate limiting to installation generation requests to prevent mass requests
# Configure web server or application rate limiting based on your environment
Monitor and clean temp directory
linuxImplement monitoring and automated cleanup of the webinstaller temp directory
# Set up cron job or scheduled task to clean old temp files
# Example: find /path/to/webinstaller/temp -type f -mtime +1 -delete
🧯 If You Can't Patch
- Isolate the webinstaller service on a separate network segment with limited access
- Implement strict firewall rules to limit access to the webinstaller port
🔍 How to Verify
Check if Vulnerable:
Check if webinstaller is running and accessible, and review version against vendor advisoryCheck Version:
# Check webinstaller version - method varies by deploymentVerify Fix Applied:
Verify patched version is installed and test that repeated installation requests no longer fill temp directory📡 Detection & Monitoring
Log Indicators:
- Rapid succession of installation generation requests
- Disk space warnings for temp directory
- Webinstaller service restart events
Network Indicators:
- High volume of requests to webinstaller installation endpoint
- Unusual source IPs generating installation requests
SIEM Query:
source="webinstaller" AND (event="installation_request" count>100 per hour) OR disk_usage>90%