CVE-2022-21993
📋 TL;DR
This vulnerability in Windows Services for NFS ONCRPC XDR Driver allows attackers to read sensitive information from kernel memory. It affects Windows systems with NFS services enabled, potentially exposing credentials or other sensitive data.
💻 Affected Systems
- Windows Services for NFS
📦 What is this software?
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 10 by Microsoft
Windows 11 by Microsoft
Windows 11 by Microsoft
Windows 8.1 by Microsoft
Windows 8.1 by Microsoft
Windows Rt 8.1 by Microsoft
Windows Server by Microsoft
Windows Server by Microsoft
⚠️ Risk & Real-World Impact
Worst Case
Attackers could extract sensitive kernel memory contents including credentials, encryption keys, or other system secrets leading to privilege escalation or lateral movement.
Likely Case
Information disclosure of kernel memory contents that could aid in further attacks or expose sensitive system information.
If Mitigated
Limited impact with proper network segmentation and access controls preventing unauthorized access to NFS services.
🎯 Exploit Status
Requires attacker to have access to the NFS service and ability to send specially crafted requests.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: January 2022 security updates (KB5009557 for Windows 10 21H2, KB5009555 for Windows 10 21H1, etc.)
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2022-21993
Restart Required: Yes
Instructions:
1. Install the January 2022 Windows security updates from Windows Update. 2. Alternatively, download and install the specific KB patch for your Windows version. 3. Restart the system to complete the installation.
🔧 Temporary Workarounds
Disable Windows Services for NFS
windowsRemove or disable the vulnerable component if not required
Remove-WindowsFeature FS-NFS-Service (PowerShell)
dism /online /disable-feature /featurename:ServerForNFS-Infrastructure (Command Prompt)
Network segmentation
windowsRestrict access to NFS services using firewall rules
New-NetFirewallRule -DisplayName "Block NFS" -Direction Inbound -Protocol TCP -LocalPort 2049 -Action Block (PowerShell)
🧯 If You Can't Patch
- Disable Windows Services for NFS if not required for business operations
- Implement strict network access controls to limit which systems can access NFS services
🔍 How to Verify
Check if Vulnerable:
Check if Windows Services for NFS is installed: Get-WindowsFeature FS-NFS-Service | Select-Object InstalledCheck Version:
systeminfo | findstr /B /C:"OS Name" /C:"OS Version"Verify Fix Applied:
Verify January 2022 security updates are installed: Get-HotFix -Id KB5009557, KB5009555, or other relevant KB numbers📡 Detection & Monitoring
Log Indicators:
- Unusual NFS service activity in Windows Event Logs
- Failed authentication attempts to NFS services
Network Indicators:
- Unusual traffic to NFS port 2049
- Multiple failed NFS protocol requests
SIEM Query:
source="windows" AND (event_id=4625 OR event_id=4771) AND service_name="NFS"