CriticalCVE-2024-43451

    NTLM Hash Disclosure Spoofing Vulnerability (CVE-2024-43451)

    Published In CISA KEV since Sources: pwn.watch, CVE.org, Msrc Update Guide

    What is affected, what to do

    NTLM Hash Disclosure Spoofing Vulnerability

    The vulnerability is being actively exploited; treat it as a priority. Update Microsoft Windows Server 2025 to version 10.0.26100.2314, Microsoft Windows Server 2025 (Server Core installation) to version 10.0.26100.2314, Microsoft Windows 10 Version 1809 to version 10.0.17763.6532. Immediate actions, mitigation and detection rules are in the runbook below.

    Affected
    • Microsoft Windows Server 2025 lt 10.0.26100.0..10.0.26100.2314
    • Microsoft Windows Server 2025 (Server Core installation) lt 10.0.26100.0..10.0.26100.2314
    • Microsoft Windows 10 Version 1809 lt 10.0.17763.0..10.0.17763.6532
    • Microsoft Windows Server 2019 lt 10.0.17763.0..10.0.17763.6532
    • Microsoft Windows Server 2019 (Server Core installation) lt 10.0.17763.0..10.0.17763.6532
    • Microsoft Windows Server 2022 lt 10.0.20348.0..10.0.20348.2849
    • Microsoft Windows 10 Version 21H2 lt 10.0.19043.0..10.0.19044.5131
    • Microsoft Windows 11 version 22H2 lt 10.0.22621.0..10.0.22621.4460
    • Microsoft Windows 10 Version 22H2 lt 10.0.19045.0..10.0.19045.5131
    • Microsoft Windows 11 version 22H3 lt 10.0.22631.0..10.0.22631.4460
    • Microsoft Windows 11 Version 23H2 lt 10.0.22631.0..10.0.22631.4460
    • Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) lt 10.0.25398.0..10.0.25398.1251
    • Microsoft Windows 11 Version 24H2 lt 10.0.26100.0..10.0.26100.2314
    • Microsoft Windows 10 Version 1507 lt 10.0.10240.0..10.0.10240.20826
    • Microsoft Windows 10 Version 1607 lt 10.0.14393.0..10.0.14393.7515
    • Microsoft Windows Server 2016 lt 10.0.14393.0..10.0.14393.7515
    • Microsoft Windows Server 2016 (Server Core installation) lt 10.0.14393.0..10.0.14393.7515
    • Microsoft Windows Server 2008 Service Pack 2 lt 6.0.6003.0..6.0.6003.22966
    • Microsoft Windows Server 2008 Service Pack 2 (Server Core installation) lt 6.0.6003.0..6.0.6003.22966
    • Microsoft Windows Server 2008 R2 Service Pack 1 lt 6.1.7601.0..6.1.7601.27415
    • Microsoft Windows Server 2008 R2 Service Pack 1 (Server Core installation) lt 6.1.7601.0..6.1.7601.27415
    • Microsoft Windows Server 2012 R2 lt 6.3.9600.0..6.3.9600.22267
    • Microsoft Windows Server 2012 R2 (Server Core installation) lt 6.3.9600.0..6.3.9600.22267
    Fixed in
    • Microsoft Windows Server 2025 10.0.26100.2314
    • Microsoft Windows Server 2025 (Server Core installation) 10.0.26100.2314
    • Microsoft Windows 10 Version 1809 10.0.17763.6532
    • Microsoft Windows Server 2019 10.0.17763.6532
    • Microsoft Windows Server 2019 (Server Core installation) 10.0.17763.6532
    • Microsoft Windows Server 2022 10.0.20348.2849
    • Microsoft Windows 10 Version 21H2 10.0.19044.5131
    • Microsoft Windows 11 version 22H2 10.0.22621.4460
    • Microsoft Windows 10 Version 22H2 10.0.19045.5131
    • Microsoft Windows 11 version 22H3 10.0.22631.4460
    • Microsoft Windows 11 Version 23H2 10.0.22631.4460
    • Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.1251
    • Microsoft Windows 11 Version 24H2 10.0.26100.2314
    • Microsoft Windows 10 Version 1507 10.0.10240.20826
    • Microsoft Windows 10 Version 1607 10.0.14393.7515
    • Microsoft Windows Server 2016 10.0.14393.7515
    • Microsoft Windows Server 2016 (Server Core installation) 10.0.14393.7515
    • Microsoft Windows Server 2008 Service Pack 2 6.0.6003.22966
    • Microsoft Windows Server 2008 Service Pack 2 (Server Core installation) 6.0.6003.22966
    • Microsoft Windows Server 2008 R2 Service Pack 1 6.1.7601.27415
    • Microsoft Windows Server 2008 R2 Service Pack 1 (Server Core installation) 6.1.7601.27415
    • Microsoft Windows Server 2012 R2 6.3.9600.22267
    • Microsoft Windows Server 2012 R2 (Server Core installation) 6.3.9600.22267

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    6.5

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: NVD, CVSS v3

    6.5

    CVSS v3

    Severity Medium on the scale from 0 to 10.

    Source: pwn.watch, CVE.org, Msrc Update Guide

    84.3 %

    EPSS score

    High — model estimates ≥ 50% chance of real-world exploitation within 30 days.

    Source: FIRST EPSS, percentile 99.70

    Show all metrics
    Severity
    Critical
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    218.87 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    actively exploited
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    6.5 Methodology
    CVSS v3

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    6.5
    EPSS score

    The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.

    Read in glossary
    84.3 %
    High — model estimates ≥ 50% chance of real-world exploitation within 30 days.
    EPSS percentile

    The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.

    Read in glossary
    99.70
    Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    Actively exploited
    Published
    In CISA KEV since

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-73

    Response and mitigation

    Why act now?

    Prioritisation rationale

    Exploitation needs only minimal user interaction with a crafted file – selecting it, right-clicking it or opening it is enough. Windows then leaks the logged-on user's NTLMv2 hash to an attacker-controlled server. That makes it an ideal phishing initial-access primitive, and it was used as a targeted zero-day before the patch shipped. The base severity looks moderate (network-reachable, no authentication, confidentiality impact only), yet it ranks among the CVEs most likely to be exploited. The real damage comes downstream, through offline cracking and NTLM relay against poorly hardened services such as AD CS or Exchange. Organisations with open SMB egress, heavy NTLM dependence or missing SMB signing should remediate within 72 hours. Where egress is locked down and signing is enforced, the normal patch cycle is acceptable, backed by heightened monitoring.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Deploy the Microsoft November 2024 security update to all Windows clients and verify build levels. Minimum builds: Windows 10 1507 10.0.10240.20826, 1607 10.0.14393.7515, 1809 10.0.17763.6532, 21H2 10.0.19044.5131, 22H2 10.0.19045.5131, Windows 11 22H2 10.0.22621.4460, 23H2 10.0.22631.4460. Look up the matching KB numbers and affected Server editions in the vendor advisory.
      • Block outbound SMB (TCP 445/139) to the internet at the perimeter firewall if not already enforced. Exploitation pushes the victim's NTLMv2 authentication to an attacker-controlled server.
      • Add privileged accounts (Domain Admins, Tier-0/1, help desk) to the "Protected Users" group. This disables NTLM for those identities and renders a leaked hash useless.
      • Configure the mail gateway and web proxy to quarantine .url, .lnk and .library-ms attachments, including those nested in archives. Retro-hunt delivered mail from the last 14 days.
      • Inventory unpatchable legacy hosts (out-of-support Windows 10, kiosks, OT HMIs) and cut them off from internet, email and browsing.
      • Where disclosure is suspected, reset the affected accounts' passwords. NTLMv2 hashes can be cracked offline and relayed.

    2. Runbook step 2

      Mitigation layers

      • Network segmentation: Apply egress allow-listing for SMB and WebDAV. Permit TCP 445 only to internal file servers. Block WebDAV over HTTP/S (User-Agent Microsoft-WebDAV-MiniRedir) at the proxy and prevent NTLM auth to external proxy destinations.
      • Endpoint hardening: Disable the WebClient service via GPO wherever WebDAV is not required. This closes the HTTP fallback path once SMB is blocked. Enforce Mark-of-the-Web and SmartScreen.
      • IAM / NTLM restriction: Set the GPO "Network security: Restrict NTLM: Outgoing NTLM traffic to remote servers" to "Audit all" first. Then move it to "Deny all" with an allow-list of internal servers. Disable NTLMv1/LM via "LAN Manager authentication level" = "Send NTLMv2 response only. Refuse LM & NTLM".
      • Relay protection: Require SMB signing on all servers. Enable LDAP signing and channel binding on domain controllers. Turn on Extended Protection for Authentication (EPA) for AD CS Web Enrollment, Exchange and IIS sites using Windows auth.
      • IPS/WAF: Add a Suricata or Snort rule matching outbound SMB2 NTLMSSP_AUTH (NTLMSSP\x00\x03\x00\x00\x00) to non-RFC1918 destinations. Run it in alert mode first, then switch to drop.
      • Password policy: Enforce a minimum length of 15 characters or more so that offline cracking of harvested NTLMv2 hashes becomes uneconomical.

    3. Runbook step 3

      Detection rules

      • Sysmon EID 3 / MDE DeviceNetworkEvents: Look for outbound connections on port 445 to public IPs initiated by explorer.exe or System. KQL: DeviceNetworkEvents | where RemotePort in (445,139) and RemoteIPType == "Public" | summarize count() by DeviceName, InitiatingProcessFileName, RemoteIP
      • NTLM operational log (Microsoft-Windows-NTLM/Operational, EID 8001): Flag outgoing NTLM authentication to targets outside your own domain. This requires the audit GPO above.
      • Process creation (Sysmon EID 1 / Security 4688): rundll32.exe with davclnt.dll,DavSetCookie and an external URL indicates WebDAV-based hash leakage. Sigma shape: CommandLine|contains|all: ['davclnt.dll','DavSetCookie','http'].
      • Sysmon EID 11 / EID 15: Watch for .url files written to Downloads, %TEMP% or the Outlook cache. Prioritise files carrying a Zone.Identifier (internet origin) that are followed by external SMB/WebDAV traffic within 60 seconds.
      • Security EID 4624 (LogonType 3, AuthenticationPackage NTLM) on servers: Privileged-account logons from unusual source IPs, or without a preceding Kerberos TGT, suggest relay or pass-the-hash. Complement this with Zeek ntlm.log hunting for domain and user names sent to external hosts.

    Detection rules

    No NEOSEC detection rule is available for this vulnerability yet.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    Actively exploited: treat the vulnerability as a priority in vulnerability handling under Art. 21(2)(e) NIS2. If it is exploited in your environment, check the reporting obligation under Art. 23 (early warning within 24 hours).
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    Since 11.09.2026, manufacturers of affected products with digital elements must report actively exploited vulnerabilities under Art. 14 CRA, with an early warning within 24 hours via ENISA's single reporting platform.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    Description

    NTLM Hash Disclosure Spoofing Vulnerability

    Source: pwn.watch, NVD (NIST), Microsoft Security Update Guide, cvelistv5, CISA KEV Catalog, CVE.org (MITRE)

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    MicrosoftWindows 10 Version 1507
    • 10.0.10240.0 – < 10.0.10240.20826
    • 10.0.10240.20826
    MicrosoftWindows 10 Version 1607
    • 10.0.14393.0 – < 10.0.14393.7515
    • 10.0.14393.7515
    MicrosoftWindows 10 Version 1809
    • 10.0.17763.0 – < 10.0.17763.6532
    • 10.0.17763.6532
    MicrosoftWindows 10 Version 21H2
    • 10.0.19043.0 – < 10.0.19044.5131
    • 10.0.19044.5131
    MicrosoftWindows 10 Version 22H2
    • 10.0.19045.0 – < 10.0.19045.5131
    • 10.0.19045.5131
    MicrosoftWindows 11 version 22H2
    • 10.0.22621.0 – < 10.0.22621.4460
    • 10.0.22621.4460
    MicrosoftWindows 11 version 22H3
    • 10.0.22631.0 – < 10.0.22631.4460
    • 10.0.22631.4460
    MicrosoftWindows 11 Version 23H2
    • 10.0.22631.0 – < 10.0.22631.4460
    • 10.0.22631.4460
    MicrosoftWindows 11 Version 24H2
    • 10.0.26100.0 – < 10.0.26100.2314
    • 10.0.26100.2314
    MicrosoftWindows Server 2008 R2 Service Pack 1
    • 6.1.7601.0 – < 6.1.7601.27415
    • 6.1.7601.27415
    MicrosoftWindows Server 2008 R2 Service Pack 1 (Server Core installation)
    • 6.1.7601.0 – < 6.1.7601.27415
    • 6.1.7601.27415
    MicrosoftWindows Server 2008 Service Pack 2
    • 6.0.6003.0 – < 6.0.6003.22966
    • 6.0.6003.22966
    MicrosoftWindows Server 2008 Service Pack 2 (Server Core installation)
    • 6.0.6003.0 – < 6.0.6003.22966
    • 6.0.6003.22966
    MicrosoftWindows Server 2012 R2
    • 6.3.9600.0 – < 6.3.9600.22267
    • 6.3.9600.22267
    MicrosoftWindows Server 2012 R2 (Server Core installation)
    • 6.3.9600.0 – < 6.3.9600.22267
    • 6.3.9600.22267
    MicrosoftWindows Server 2016
    • 10.0.14393.0 – < 10.0.14393.7515
    • 10.0.14393.7515
    MicrosoftWindows Server 2016 (Server Core installation)
    • 10.0.14393.0 – < 10.0.14393.7515
    • 10.0.14393.7515
    MicrosoftWindows Server 2019
    • 10.0.17763.0 – < 10.0.17763.6532
    • 10.0.17763.6532
    MicrosoftWindows Server 2019 (Server Core installation)
    • 10.0.17763.0 – < 10.0.17763.6532
    • 10.0.17763.6532
    MicrosoftWindows Server 2022
    • 10.0.20348.0 – < 10.0.20348.2849
    • 10.0.20348.2849
    MicrosoftWindows Server 2022, 23H2 Edition (Server Core installation)
    • 10.0.25398.0 – < 10.0.25398.1251
    • 10.0.25398.1251
    MicrosoftWindows Server 2025
    • 10.0.26100.0 – < 10.0.26100.2314
    • 10.0.26100.2314
    MicrosoftWindows Server 2025 (Server Core installation)
    • 10.0.26100.0 – < 10.0.26100.2314
    • 10.0.26100.2314

    Vendors and products

    Affected operating systems

    Affected operating systems
    Windowsmicrosoftwindows_10_1507—
    Windowsmicrosoftwindows_10_1607—
    Windowsmicrosoftwindows_10_1809—
    Windowsmicrosoftwindows_10_21h2—
    Windowsmicrosoftwindows_10_22h2—
    Windowsmicrosoftwindows_11_22h2—
    Windowsmicrosoftwindows_11_23h2—
    Windowsmicrosoftwindows_11_24h2—
    Windowsmicrosoftwindows_server_2008r2
    Windowsmicrosoftwindows_server_2008—
    Windowsmicrosoftwindows_server_2012r2
    Windowsmicrosoftwindows_server_2012—
    Windowsmicrosoftwindows_server_2016—
    Windowsmicrosoftwindows_server_2019—
    Windowsmicrosoftwindows_server_2022—
    Windowsmicrosoftwindows_server_2022_23h2—
    Windowsmicrosoftwindows_server_2025—

    Weakness classes (CWE)

    • CWE-73External Control of File Name or Path

      Base

      The product allows user input to control or influence paths or file names that are used in filesystem operations.

      Entry at MITRE CWE-73

    Public exploit references

    Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.

    Public exploit references
    CISA KEV CatalogCISA Known Exploited Vulnerability (opens in a new tab)cisa.govactively exploited
    PoC-in-GitHub (nomi-sec)cve-2024-43451-ntlm_hash_disclosure_reproduction (opens in a new tab)github.comPoC (publicly reported)reported, not verified

    References & sources

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    Badge preview for CVE-2024-43451
    <a href="https://intel.neosec.eu/en/cve/CVE-2024-43451"><img src="https://intel.neosec.eu/badge/cve/CVE-2024-43451.svg?lang=en" alt="CVE-2024-43451 – NEOSEC Intel" height="20"></a>