Microsoft Windows NTLM Hash Disclosure and Spoofing Vulnerability (CVE-2024-43451) Critical Security Advisory
Executive & SecOps Summary
SECOPS ASSESSMENTAll supported versions of Microsoft Windows and Windows Server operating systems
Simple user interaction with a malicious file (such as right-clicking or selecting) triggers NTLM credential disclosure, enabling credential theft and NTLM Relay attacks
Immediately apply the Microsoft November 2024 cumulative security updates and restrict outbound NTLM traffic via Group Policy and firewalls
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
Refer to the Microsoft Security Update Guide to apply the latest cumulative updates. You can verify and force the installation of the required KB updates using PowerShell.
# Install Windows Update module and apply the latest security updates
Install-Module PSWindowsUpdate -Force -SkipPublisherCheck
Get-WindowsUpdate -KBArticleID 'KB5046613' -Install -AcceptAll -AutoReboot2. Temporary Workaround & Hardening Configuration
If immediate patching is not feasible, restrict outbound NTLM traffic using Group Policy or Registry modifications, and block outbound SMB traffic at the network perimeter.
# Block outbound SMB (TCP Port 445) at the perimeter firewall
iptables -A OUTPUT -p tcp --dport 445 -j DROP# Restrict outbound NTLM traffic via Registry modification
New-ItemProperty -Path 'HKLM:\SYSTEM\CurrentControlSet\Control\Lsa\MSV1_0' -Name 'RestrictSendingNTLMTraffic' -PropertyType DWord -Value 2 -Force3. Log Audit & IoC Verification Commands
Monitor Event Viewer for outbound SMB connection attempts and NTLM authentication logs. Use the following script to audit NTLM block/audit events.
# Query NTLM Operational event logs for block or audit events (Event ID 8001, 8002)
Get-WinEvent -LogName 'Microsoft-Windows-NTLM/Operational' | Where-Object { $_.Id -eq 8001 -or $_.Id -eq 8002 } | Select-Object TimeCreated, Id, Message -First 20Block Kernel Privilege Escalation & Ransomware Payloads Before You Can Reboot
Protect unpatched Windows, Linux, and macOS workloads against in-memory exploitation and lateral movement with autonomous EDR.
Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability (CVE-2024-43451) is an NTLM Hash Disclosure and Spoofing vulnerability that occurs when the Windows operating system processes specific files and shortcut icons. Due to improper restriction of file path references (CWE-73), the system forces an NTLM authentication session to a remote SMB server during file metadata parsing or preview generation, requiring minimal user interaction.
2. Exploitation Mechanics & Attack Scenario
An attacker crafts a malicious file (such as a specially designed shortcut or folder structure) and delivers it via email attachments, instant messages, or shared network drives. The vulnerability is triggered without the user executing the file; simply right-clicking to open the context menu, single-clicking to select, or opening a directory with 'Preview Pane' enabled in File Explorer is sufficient. Windows then automatically initiates an outbound SMB connection to the attacker-controlled server, transmitting the victim's NTLM challenge/response hash.
3. Infrastructure & Business Impact
Exposed NTLM hashes can be cracked offline using brute-force tools to recover plaintext passwords, or leveraged in NTLM Relay attacks against other vulnerable systems within the same network. In an Active Directory (AD) environment, this can lead to domain privilege escalation and lateral movement, potentially resulting in full domain compromise. This vulnerability has been actively exploited in the wild as a zero-day and is listed in the CISA KEV catalog.
Official Vendor Advisories & References
NTLM Hash Disclosure Spoofing Vulnerability
Frequently Asked SecOps Questions (CVE-2024-43451)
FAQQ1. How critical is CVE-2024-43451 and is it actively exploited in the wild?
CVE-2024-43451 is rated CVSS 6.5 (MEDIUM) with a 30-day EPSS exploitation probability of 84.3%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2024-43451?
Primary impacted vendors include microsoft across windows, windows_server. Scope summary: All supported and extended support versions of Windows 10, Windows 11, and Windows Server (2008 through 2022)
Q3. What temporary mitigations or workarounds exist for CVE-2024-43451 before patching?
[Mitigation] Immediately apply the Microsoft November 2024 cumulative security updates and restrict outbound NTLM traffic via Group Policy and firewalls Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
Generate an Internal Engineering Notice or CISO Report for CVE-2024-43451
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