CVE-2022-24491
📋 TL;DR
This is a critical remote code execution vulnerability in Windows Network File System (NFS) that allows unauthenticated attackers to execute arbitrary code on vulnerable systems. It affects Windows servers with NFS enabled, potentially allowing complete system compromise. The vulnerability is network-accessible and doesn't require user interaction.
💻 Affected Systems
- Windows Server
📦 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 11 by Microsoft
Windows 11 by Microsoft
Windows 8.1 by Microsoft
Windows Rt 8.1 by Microsoft
⚠️ Risk & Real-World Impact
Worst Case
Complete system takeover with administrative privileges, enabling data theft, ransomware deployment, lateral movement, and persistent backdoor installation.
Likely Case
Remote code execution leading to credential harvesting, data exfiltration, and deployment of additional malware payloads.
If Mitigated
Limited impact if NFS is disabled or properly firewalled, with attackers unable to reach vulnerable services.
🎯 Exploit Status
Public exploit code exists, making exploitation relatively straightforward for attackers with network access to vulnerable systems.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: March 2022 security updates (KB5011551 for Server 2022, KB5011552 for Server 2019, etc.)
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2022-24491
Restart Required: Yes
Instructions:
1. Apply March 2022 Windows Server security updates from Microsoft Update. 2. Restart affected systems. 3. Verify NFS service is running post-patch if required for operations.
🔧 Temporary Workarounds
Disable NFS Service
windowsDisable the Network File System service if not required for operations
sc config nfsserver start= disabled
sc stop nfsserver
Block NFS Ports
windowsBlock network access to NFS ports (typically 2049/tcp, 2049/udp) using firewall rules
New-NetFirewallRule -DisplayName "Block NFS" -Direction Inbound -Protocol TCP -LocalPort 2049 -Action Block
New-NetFirewallRule -DisplayName "Block NFS UDP" -Direction Inbound -Protocol UDP -LocalPort 2049 -Action Block
🧯 If You Can't Patch
- Disable NFS service immediately if not required for business operations
- Implement strict network segmentation and firewall rules to isolate NFS servers from untrusted networks
🔍 How to Verify
Check if Vulnerable:
Check if NFS service is running and Windows Server version is affected: Get-Service nfsserver | Select Status, Name and systeminfo | findstr /B /C:"OS Name" /C:"OS Version"Check Version:
systeminfo | findstr /B /C:"OS Name" /C:"OS Version"Verify Fix Applied:
Verify March 2022 security updates are installed: Get-HotFix -Id KB5011551, KB5011552, or relevant KB for your version📡 Detection & Monitoring
Log Indicators:
- Unusual NFS service crashes or restarts
- Failed NFS authentication attempts from unexpected sources
- Windows Security logs showing unexpected process creation
Network Indicators:
- Unusual traffic to NFS port 2049 from unexpected sources
- Multiple connection attempts to NFS service from single IPs
- Malformed NFS packets in network traffic
SIEM Query:
source="windows-security" EventCode=4688 AND (NewProcessName="*cmd.exe" OR NewProcessName="*powershell.exe") AND ParentProcessName="*svchost.exe" AND ParentCommandLine="*nfsserver*"