CVE-2023-28247
📋 TL;DR
This vulnerability in Windows Network File System (NFS) allows an attacker to read sensitive information from memory that should be protected. It affects Windows servers running NFS services. Attackers could potentially access credentials or other confidential data.
💻 Affected Systems
- Windows Server
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers could extract authentication credentials, encryption keys, or other sensitive data from memory, leading to lateral movement, privilege escalation, or data breaches.
Likely Case
Information disclosure of system memory contents, potentially exposing sensitive data that could be used in further attacks.
If Mitigated
Limited impact with proper network segmentation and access controls preventing unauthorized NFS access.
🎯 Exploit Status
Requires attacker to have access to NFS service and ability to send crafted requests. No public exploit code available as of knowledge cutoff.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: April 2023 security updates (KB5025239 for Server 2022, KB5025224 for Server 2019, etc.)
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-28247
Restart Required: Yes
Instructions:
1. Apply April 2023 Windows Server security updates via Windows Update. 2. Alternatively, download and install the specific KB patch for your Windows Server version. 3. Restart the server after installation.
🔧 Temporary Workarounds
Disable NFS Service
windowsIf NFS functionality is not required, disable the NFS server role to eliminate the attack surface.
Remove-WindowsFeature FS-NFS-Service
sc config nfsserver start= disabled
net stop nfsserver
Restrict NFS Access
windowsConfigure NFS share permissions and firewall rules to limit access to trusted hosts only.
netsh advfirewall firewall add rule name="Restrict NFS" dir=in action=allow protocol=TCP localport=2049 remoteip=192.168.1.0/24
netsh advfirewall firewall add rule name="Restrict NFS UDP" dir=in action=allow protocol=UDP localport=2049 remoteip=192.168.1.0/24
🧯 If You Can't Patch
- Implement strict network segmentation to isolate NFS servers from untrusted networks
- Monitor NFS logs for unusual access patterns or connection attempts
🔍 How to Verify
Check if Vulnerable:
Check if NFS service is running and Windows Server version is affected: Get-WindowsFeature FS-NFS-Service | Select-Object Installed; systeminfo | findstr /B /C:"OS Name" /C:"OS Version"Check Version:
systeminfo | findstr /B /C:"OS Name" /C:"OS Version"Verify Fix Applied:
Verify April 2023 security updates are installed: Get-HotFix -Id KB5025239, KB5025224, or other relevant KB numbers📡 Detection & Monitoring
Log Indicators:
- Unusual NFS connection attempts in Windows Event Logs (Security/System)
- Multiple failed NFS authentication attempts
- NFS service errors or crashes
Network Indicators:
- Unusual traffic to TCP/UDP port 2049 from unexpected sources
- Multiple NFS protocol requests in short timeframes
SIEM Query:
source="Windows Security" EventCode=4625 OR EventCode=4648 | where ProcessName contains "nfsserver" OR ServiceName contains "NFS"