CriticalCVE-2024-38217

    Windows Mark of the Web Security Feature Bypass Vulnerability (CVE-2024-38217)

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

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    What is affected, what to do

    Windows Mark of the Web Security Feature Bypass Vulnerability

    The vulnerability is being actively exploited; treat it as a priority. Update Microsoft Windows 10 Version 1507 to version 10.0.10240.20766, Microsoft Windows 10 Version 1607 to version 10.0.14393.7336, Microsoft Windows 10 Version 1809 to version 10.0.17763.6293. Immediate actions, mitigation and detection rules are in the runbook below.

    Affected
    • Microsoft Windows 10 Version 1507 lt 10.0.10240.0..10.0.10240.20766
    • Microsoft Windows 10 Version 1607 lt 10.0.14393.0..10.0.14393.7336
    • Microsoft Windows 10 Version 1809 lt 10.0.17763.0..10.0.17763.6293
    • Microsoft Windows 10 Version 21H2 lt 10.0.19043.0..10.0.19044.4894
    • Microsoft Windows 10 Version 22H2 lt 10.0.19045.0..10.0.19045.4894
    • Microsoft Windows 11 version 21H2 lt 10.0.0..10.0.22000.3197
    • Microsoft Windows 11 version 22H2 lt 10.0.22621.0..10.0.22621.4169
    • Microsoft Windows 11 version 22H3 lt 10.0.22631.0..10.0.22631.4169
    • Microsoft Windows 11 Version 23H2 lt 10.0.22631.0..10.0.22631.4169
    • Microsoft Windows 11 Version 24H2 lt 10.0.26100.0..10.0.26100.1742
    • Microsoft Windows Server 2008 Service Pack 2 lt 6.0.6003.0..6.0.6003.22870
    • Microsoft Windows Server 2008 R2 Service Pack 1 lt 6.1.7601.0..6.1.7601.27320
    • Microsoft Windows Server 2008 R2 Service Pack 1 (Server Core installation) lt 6.1.7601.0..6.1.7601.27320
    • Microsoft Windows Server 2008 Service Pack 2 (Server Core installation) lt 6.0.6003.0..6.0.6003.22870
    • Microsoft Windows Server 2012 lt 6.2.9200.0..6.2.9200.25073
    • Microsoft Windows Server 2012 (Server Core installation) lt 6.2.9200.0..6.2.9200.25073
    • Microsoft Windows Server 2012 R2 lt 6.3.9600.0..6.3.9600.22175
    • Microsoft Windows Server 2012 R2 (Server Core installation) lt 6.3.9600.0..6.3.9600.22175
    • Microsoft Windows Server 2016 lt 10.0.14393.0..10.0.14393.7336
    • Microsoft Windows Server 2016 (Server Core installation) lt 10.0.14393.0..10.0.14393.7336
    • Microsoft Windows Server 2019 lt 10.0.17763.0..10.0.17763.6293
    • Microsoft Windows Server 2019 (Server Core installation) lt 10.0.17763.0..10.0.17763.6293
    • Microsoft Windows Server 2022 lt 10.0.20348.0..10.0.20348.2700
    • Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) lt 10.0.25398.0..10.0.25398.1128
    Fixed in
    • Microsoft Windows 10 Version 1507 10.0.10240.20766
    • Microsoft Windows 10 Version 1607 10.0.14393.7336
    • Microsoft Windows 10 Version 1809 10.0.17763.6293
    • Microsoft Windows 10 Version 21H2 10.0.19044.4894
    • Microsoft Windows 10 Version 22H2 10.0.19045.4894
    • Microsoft Windows 11 version 21H2 10.0.22000.3197
    • Microsoft Windows 11 version 22H2 10.0.22621.4169
    • Microsoft Windows 11 version 22H3 10.0.22631.4169
    • Microsoft Windows 11 Version 23H2 10.0.22631.4169
    • Microsoft Windows 11 Version 24H2 10.0.26100.1742
    • Microsoft Windows Server 2008 Service Pack 2 6.0.6003.22870
    • Microsoft Windows Server 2008 R2 Service Pack 1 6.1.7601.27320
    • Microsoft Windows Server 2008 R2 Service Pack 1 (Server Core installation) 6.1.7601.27320
    • Microsoft Windows Server 2008 Service Pack 2 (Server Core installation) 6.0.6003.22870
    • Microsoft Windows Server 2012 6.2.9200.25073
    • Microsoft Windows Server 2012 (Server Core installation) 6.2.9200.25073
    • Microsoft Windows Server 2012 R2 6.3.9600.22175
    • Microsoft Windows Server 2012 R2 (Server Core installation) 6.3.9600.22175
    • Microsoft Windows Server 2016 10.0.14393.7336
    • Microsoft Windows Server 2016 (Server Core installation) 10.0.14393.7336
    • Microsoft Windows Server 2019 10.0.17763.6293
    • Microsoft Windows Server 2019 (Server Core installation) 10.0.17763.6293
    • Microsoft Windows Server 2022 10.0.20348.2700
    • Microsoft Windows Server 2022, 23H2 Edition (Server Core installation) 10.0.25398.1128

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

    Metrics

    5.4

    Priority

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

    Source: NVD, CVSS v3

    5.4

    CVSS v3

    Severity Medium on the scale from 0 to 10.

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

    10.0 %

    EPSS score

    Elevated — model estimates 10-50% exploitation likelihood.

    Source: FIRST EPSS, percentile 95.6

    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
    206.32 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
    5.4 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
    5.4
    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
    10.0 %
    Elevated — model estimates 10-50% exploitation likelihood.
    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
    95.6
    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
    CISA assessment (SSVC)
    Exploitation: active · not automatable · Technical impact: partial
    Source: CISA Vulnrichment, as of 11 September 2024
    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-693

    Response and mitigation

    Why act now?

    Prioritisation rationale

    The flaw is triggered remotely by an unauthenticated attacker but requires user interaction. Its direct impact is limited; its value to attackers is that it defeats SmartScreen, Smart App Control and Office Protected View. That makes it a standard building block in phishing and drive-by chains for initial access and payload delivery. Its exploitation likelihood is very high compared with other CVEs. CISA does not flag known ransomware use, but as an initial-access enabler it remains relevant to ransomware intrusions. Organisations with large client fleets and heavy email exposure should treat it as high priority and close it within an emergency patch window of a few days. Server-only segments without interactive users can be scheduled behind those clients.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Deploy the September 2024 cumulative security update to all affected Windows clients. Target builds per the advisory: Windows 10 1507 ≥ 10.0.10240.20766, 1607 ≥ 10.0.14393.7336, 1809 ≥ 10.0.17763.6293, 21H2 ≥ 10.0.19044.4894, 22H2 ≥ 10.0.19045.4894, Windows 11 21H2 ≥ 10.0.22000.3197, 22H2 ≥ 10.0.22621.4169, 23H2/"22H3" ≥ 10.0.22631.4169. Look up the matching KB ID per build in the Microsoft Security Update Guide.
      • Pull patch compliance from Intune, WSUS, SCCM or your EDR inventory and tag anything below the target build as high risk. Patch mail- and browser-heavy endpoints first, such as office staff, finance and HR.
      • Block or quarantine .lnk files at the mail gateway and web proxy now. Include LNKs nested in ZIP, 7z, RAR, ISO, IMG and VHD containers. The bypass relies on crafted shortcut files that lose their Zone.Identifier when opened.
      • Hunt back 30 days for delivered LNK attachments and downloads. Treat any hit followed by script or LOLBin execution as an incident: isolate the host and reset the user's credentials.
      • Brief users and the service desk that SmartScreen and Protected View prompts may silently fail on unpatched systems. A missing warning on those systems does not mean the file is safe.

    2. Runbook step 2

      Mitigation layers

      • Mail/web filtering: Block the file types .lnk, .url, .hta, .js, .jse, .vbs, .vbe, .wsf and .scf, with archive and disk-image inspection enabled. Block container formats (ISO, IMG, VHD) outright unless there is a business need.
      • Endpoint hardening (Defender ASR): Enforce the following rules in block mode:
        • "Block JavaScript or VBScript from launching downloaded executable content"
        • "Block execution of potentially obfuscated scripts"
        • "Block Office applications from creating child processes"
        • "Block executable files from running unless they meet a prevalence, age, or trusted list criterion"
      • Office configuration independent of MOTW: Set VBA macros to "Disable all except digitally signed macros" via GPO or Intune. Do not rely solely on the MOTW-driven internet macro block, because that is exactly the tagging being bypassed.
      • Application control: Use WDAC or AppLocker to deny script and binary execution from user-writable paths, including %USERPROFILE%\Downloads, %TEMP% and %APPDATA%. Restrict mshta.exe, wscript.exe and cscript.exe for standard users.
      • File associations: Remap .js, .vbs, .hta and .wsf to Notepad via GPO so that a double-click opens the file instead of executing it.
      • Least privilege: Remove local admin rights from standard users to limit the blast radius of a successful initial execution.

    3. Runbook step 3

      Detection rules

      • Sysmon EID 11 / MDE DeviceFileEvents – LNK rewrite by Explorer: explorer.exe writes or modifies a .lnk in Downloads or Temp paths. This is a characteristic artefact of the bypass, because the file is rewritten and the Zone.Identifier is dropped. 
        DeviceFileEvents | where FileName endswith ".lnk" and InitiatingProcessFileName =~ "explorer.exe" and ActionType in ("FileModified","FileCreated") and FolderPath has_any (@"\Downloads\", @"\AppData\Local\Temp\")
      • Sysmon EID 15 (FileCreateStreamHash): A Zone.Identifier stream is created for a file, and shortly afterwards the same file reappears rewritten without the ADS. Correlate the two events on TargetFilename.
      • Process ancestry (EDR, Sysmon EID 1, Security 4688 with command line): explorer.exe spawns powershell.exe, cmd.exe, mshta.exe, wscript.exe, cscript.exe, rundll32.exe or conhost.exe with network or encoding arguments. 
        DeviceProcessEvents | where InitiatingProcessFileName =~ "explorer.exe" and FileName in~ ("powershell.exe","mshta.exe","wscript.exe","cscript.exe","rundll32.exe","cmd.exe") and ProcessCommandLine has_any ("http","-enc","FromBase64String","iwr","curl")
      • Sigma shape: logsource: process_creation, ParentImage|endswith: \explorer.exe, Image|endswith in the LOLBin list, CommandLine|contains .lnk or download patterns. Add CurrentDirectory|contains: \Downloads\.
      • Network telemetry (Zeek/Suricata/proxy): Look for HTTP downloads with MIME type application/x-ms-shortcut and LNK magic bytes 4C 00 00 00 01 14 02 00 in file extraction. Flag outbound connections from the same client to newly registered domains immediately afterwards.

    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

    Windows Mark of the Web Security Feature Bypass Vulnerability

    Source: pwn.watch, Microsoft Security Update Guide, CISA KEV Catalog, NVD (NIST), cvelistv5, 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 – < 10.0.10240.20766
    • 10.0.10240.20766
    MicrosoftWindows 10 Version 1607
    • 10.0.14393.0 – < 10.0.14393.7336
    • 10.0.14393.7336
    MicrosoftWindows 10 Version 1809
    • 10.0.17763.0 – < 10.0.17763.6293
    • 10.0.17763.6293
    MicrosoftWindows 10 Version 21H2
    • 10.0.19043.0 – < 10.0.19044.4894
    • 10.0.19044.4894
    MicrosoftWindows 10 Version 22H2
    • 10.0.19045.0 – < 10.0.19045.4894
    • 10.0.19045.4894
    MicrosoftWindows 11 version 21H2
    • 10.0.0 – < 10.0.22000.3197
    • 10.0.22000.3197
    MicrosoftWindows 11 version 22H2
    • 10.0.22621.0 – < 10.0.22621.4169
    • 10.0.22621.4169
    MicrosoftWindows 11 version 22H3
    • 10.0.22631.0 – < 10.0.22631.4169
    • 10.0.22631.4169
    MicrosoftWindows 11 Version 23H2
    • 10.0.22631.0 – < 10.0.22631.4169
    • 10.0.22631.4169
    MicrosoftWindows 11 Version 24H2
    • 10.0.26100.0 – < 10.0.26100.1742
    • 10.0.26100.1742
    MicrosoftWindows Server 2008 R2 Service Pack 1
    • 6.1.7601.0 – < 6.1.7601.27320
    • 6.1.7601.27320
    MicrosoftWindows Server 2008 R2 Service Pack 1 (Server Core installation)
    • 6.1.7601.0 – < 6.1.7601.27320
    • 6.1.7601.27320
    MicrosoftWindows Server 2008 Service Pack 2
    • 6.0.6003.0 – < 6.0.6003.22870
    • 6.0.6003.22870
    MicrosoftWindows Server 2008 Service Pack 2 (Server Core installation)
    • 6.0.6003.0 – < 6.0.6003.22870
    • 6.0.6003.22870
    MicrosoftWindows Server 2012
    • 6.2.9200.0 – < 6.2.9200.25073
    • 6.2.9200.25073
    MicrosoftWindows Server 2012 (Server Core installation)
    • 6.2.9200.0 – < 6.2.9200.25073
    • 6.2.9200.25073
    MicrosoftWindows Server 2012 R2
    • 6.3.9600.0 – < 6.3.9600.22175
    • 6.3.9600.22175
    MicrosoftWindows Server 2012 R2 (Server Core installation)
    • 6.3.9600.0 – < 6.3.9600.22175
    • 6.3.9600.22175
    MicrosoftWindows Server 2016
    • 10.0.14393.0 – < 10.0.14393.7336
    • 10.0.14393.7336
    MicrosoftWindows Server 2016 (Server Core installation)
    • 10.0.14393.0 – < 10.0.14393.7336
    • 10.0.14393.7336
    MicrosoftWindows Server 2019
    • 10.0.17763.0 – < 10.0.17763.6293
    • 10.0.17763.6293
    MicrosoftWindows Server 2019 (Server Core installation)
    • 10.0.17763.0 – < 10.0.17763.6293
    • 10.0.17763.6293
    MicrosoftWindows Server 2022
    • 10.0.20348.0 – < 10.0.20348.2700
    • 10.0.20348.2700
    MicrosoftWindows Server 2022, 23H2 Edition (Server Core installation)
    • 10.0.25398.0 – < 10.0.25398.1128
    • 10.0.25398.1128

    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_21h2—
    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—

    Weakness classes (CWE)

    • CWE-693Protection Mechanism Failure

      Pillar

      The product does not use or incorrectly uses a protection mechanism that provides sufficient defense against directed attacks against the product.

      Entry at MITRE CWE-693

    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

    References & sources

    Changes to this CVE

    Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

    1. Record modifiedMicrosoft

      1 individual change: Affected versions (publisher)

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)changed
      Windows 10 Version 1809, Windows Server 2019, Windows Server 2019 (Server Core installation) (+22)
      Windows 10 Version 1507, Windows 10 Version 1607, Windows 10 Version 1809 (+22)

      Source identifier: secure@microsoft.com

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    Badge preview for CVE-2024-38217
    <a href="https://intel.neosec.eu/en/cve/CVE-2024-38217"><img src="https://intel.neosec.eu/badge/cve/CVE-2024-38217.svg?lang=en" alt="CVE-2024-38217 – NEOSEC Intel" height="20"></a>