CVE-2025-24996
📋 TL;DR
This vulnerability in Windows NTLM allows attackers to manipulate file paths or names during network authentication, enabling spoofing attacks. It affects systems using NTLM authentication over networks, potentially impacting Windows servers and clients that haven't applied security updates. Attackers could impersonate legitimate users or systems.
💻 Affected Systems
- Windows NTLM implementation
📦 What is this software?
Windows 10 1507 by Microsoft
Windows 10 1507 by Microsoft
Windows 10 1607 by Microsoft
Windows 10 1607 by Microsoft
Windows 10 1809 by Microsoft
Windows 10 1809 by Microsoft
Windows 10 21h2 by Microsoft
Windows 10 22h2 by Microsoft
Windows 11 22h2 by Microsoft
Windows 11 23h2 by Microsoft
Windows 11 24h2 by Microsoft
⚠️ Risk & Real-World Impact
Worst Case
Complete network compromise through credential theft, lateral movement across the network, and domain controller impersonation leading to full Active Directory compromise.
Likely Case
Unauthorized access to network resources, data exfiltration, and privilege escalation within the compromised network segment.
If Mitigated
Limited impact due to network segmentation, strong authentication requirements, and monitoring catching suspicious NTLM activity.
🎯 Exploit Status
Exploitation requires network access and ability to intercept/modify NTLM authentication traffic. Attacker needs to be positioned on the network path between client and server.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Microsoft Security Update Guide for specific KB numbers
Vendor Advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-24996
Restart Required: Yes
Instructions:
1. Apply latest Windows security updates from Microsoft. 2. Restart affected systems. 3. Verify update installation via Windows Update history or system information.
🔧 Temporary Workarounds
Disable NTLM authentication
windowsReplace NTLM with Kerberos authentication where possible
Group Policy: Computer Configuration > Windows Settings > Security Settings > Local Policies > Security Options > Network security: Restrict NTLM
Implement SMB signing
windowsRequire SMB packet signing to prevent man-in-the-middle attacks
Group Policy: Computer Configuration > Windows Settings > Security Settings > Local Policies > Security Options > Microsoft network server: Digitally sign communications (always)
🧯 If You Can't Patch
- Segment networks to limit NTLM traffic to trusted zones only
- Implement strict monitoring for NTLM authentication anomalies and failed attempts
🔍 How to Verify
Check if Vulnerable:
Check Windows Update history for missing security patches related to CVE-2025-24996Check Version:
systeminfo | findstr /B /C:"OS Name" /C:"OS Version"Verify Fix Applied:
Verify patch installation via: systeminfo | findstr /B /C:"OS Name" /C:"OS Version" and compare with patched versions in Microsoft advisory📡 Detection & Monitoring
Log Indicators:
- Unusual NTLM authentication patterns
- Failed NTLM authentication attempts from unexpected sources
- NTLM authentication to sensitive resources
Network Indicators:
- Unusual NTLM traffic patterns
- NTLM authentication attempts from unexpected network segments
- SMB traffic without required signing
SIEM Query:
EventID=4624 OR EventID=4625 AND AuthenticationPackageName="NTLM" | stats count by src_ip, dest_ip, user