CVE-2024-38068
📋 TL;DR
This vulnerability allows attackers to cause a denial of service on Windows Online Certificate Status Protocol (OCSP) servers by sending specially crafted requests. It affects Windows systems running OCSP services, potentially disrupting certificate validation and authentication processes.
💻 Affected Systems
- Windows Server
- Windows
📦 What is this software?
Windows 10 1507 by Microsoft
Windows 10 1607 by Microsoft
Windows 10 1809 by Microsoft
Windows 10 21h2 by Microsoft
Windows 10 22h2 by Microsoft
Windows 11 21h2 by Microsoft
Windows 11 22h2 by Microsoft
Windows 11 23h2 by Microsoft
⚠️ Risk & Real-World Impact
Worst Case
Complete unavailability of OCSP services, disrupting certificate validation for all clients, potentially breaking authentication systems and TLS connections that rely on certificate revocation checking.
Likely Case
Temporary service degradation or crashes of OCSP services, causing intermittent authentication failures and certificate validation issues for dependent applications.
If Mitigated
Minimal impact with proper network segmentation and monitoring; service may experience brief interruptions but can be quickly restored.
🎯 Exploit Status
Microsoft rates this as 'Exploitation More Likely' in their advisory. The vulnerability requires network access to the OCSP service but no authentication.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: July 2024 security updates or later
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-38068
Restart Required: Yes
Instructions:
1. Apply the July 2024 Windows security updates from Windows Update or WSUS. 2. Restart affected systems to complete the installation. 3. Verify the update is applied using winver or systeminfo commands.
🔧 Temporary Workarounds
Network Segmentation
allRestrict network access to OCSP servers to only trusted clients and networks
Configure firewall rules to limit inbound connections to OCSP service ports (typically TCP 80/443)
Disable OCSP if Not Required
windowsTemporarily disable OCSP services if certificate revocation checking is not critical for your environment
sc stop "OCSPSvc"
sc config "OCSPSvc" start= disabled
🧯 If You Can't Patch
- Implement strict network access controls to limit which systems can communicate with OCSP servers
- Deploy rate limiting and monitoring on OCSP services to detect and block suspicious traffic patterns
🔍 How to Verify
Check if Vulnerable:
Check if July 2024 security updates are installed using 'systeminfo | findstr /C:"KB"' or verify OS build version matches patched versions from Microsoft advisoryCheck Version:
systeminfo | findstr /B /C:"OS Name" /C:"OS Version"Verify Fix Applied:
Confirm the security update KB number from Microsoft advisory is present in installed updates and OCSP service is running normally📡 Detection & Monitoring
Log Indicators:
- Unusual volume of OCSP requests
- OCSP service crashes or restarts in Event Viewer
- Failed certificate validations in application logs
Network Indicators:
- High volume of requests to OCSP service ports
- Unusual patterns in OCSP request traffic
- Source IPs making excessive OCSP queries
SIEM Query:
source="windows" AND (event_id=7031 OR event_id=7034) AND service_name="OCSPSvc" OR destination_port=80 AND protocol="TCP" AND destination_ip="OCSP_server_ip" AND bytes_sent>threshold