CriticalCVE-2018-8414

    Microsoft Windows Shell Remote Code Execution Vulnerability (CVE-2018-8414)

    Published In CISA KEV since Sources: CVE.org

    What is affected, what to do

    A remote code execution vulnerability exists when the Windows Shell does not properly validate file paths, aka "Windows Shell Remote Code Execution Vulnerability." This affects Windows 10 Servers, Windows 10.

    The vulnerability is being actively exploited; treat it as a priority. The available sources name no fixed version. Check the vendor guidance in the references below. Immediate actions, mitigation and detection rules are in the runbook below.

    Affected
    • Microsoft Windows 10 Servers eq version 1709 (Server Core Installation)..version 1709 (Server Core Installation)
    • Microsoft Windows 10 Servers eq version 1803 (Server Core Installation)..version 1803 (Server Core Installation)
    • Microsoft Windows 10 eq Version 1703 for 32-bit Systems..Version 1703 for 32-bit Systems
    • Microsoft Windows 10 eq Version 1703 for x64-based Systems..Version 1703 for x64-based Systems
    • Microsoft Windows 10 eq Version 1709 for 32-bit Systems..Version 1709 for 32-bit Systems
    • Microsoft Windows 10 eq Version 1709 for x64-based Systems..Version 1709 for x64-based Systems
    • Microsoft Windows 10 eq Version 1803 for 32-bit Systems..Version 1803 for 32-bit Systems
    • Microsoft Windows 10 eq Version 1803 for x64-based Systems..Version 1803 for x64-based Systems

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

    Metrics

    8.8

    Priority

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

    Source: NVD, CVSS v3

    8.8

    CVSS v3

    Severity High on the scale from 0 to 10.

    Source: CVE.org

    72.6 %

    EPSS score

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

    Source: FIRST EPSS, percentile 99.44

    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
    223.11 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
    8.8 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
    8.8
    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
    72.6 %
    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
    99.44
    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: total
    Source: CISA Vulnrichment, as of 7 February 2025
    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-20

    Response and mitigation

    Why act now?

    Prioritisation rationale

    The flaw can be delivered over the network without authentication but needs user interaction. That makes it a classic phishing payload: weaponised .SettingContent-ms files or Office documents that, at the time, slipped past Office's dangerous-attachment block lists. Exploitation likelihood is rated very high, while CISA does not flag known ransomware campaign use. For organisations with a fully patched, supported Windows 10/11 estate the residual risk is low. Any remaining 1703/1709/1803 host is both unpatched and unsupported, and should be treated as a high-priority lifecycle deviation. Under NIS2 this applies especially to KRITIS-adjacent workstations and engineering stations.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Build an inventory of every host running Windows 10 build 1703, 1709 or 1803, including Server Core 1709/1803. Use your asset inventory, Intune/SCCM or Get-ComputerInfo | Select OsVersion, OsBuildNumber. These builds have been out of vendor support for years, so every hit is also a lifecycle finding.
      • Apply the fix shipped in Microsoft's August 2018 cumulative security update (Patch Tuesday). Look up the per-build KB number in Microsoft's advisory for CVE-2018-8414. The only durable remediation is an upgrade to a supported Windows release.
      • Block the .SettingContent-ms file type immediately at the mail gateway and the web proxy. Include files nested in ZIP, ISO and Office containers. Legitimate copies only ever live in C:\Windows\ImmersiveControlPanel\, so there is no business need to receive them externally.
      • Move any unpatched legacy host that cannot be updated today into an isolated VLAN with no direct internet or email access.
      • Retro-hunt mail and proxy logs for .SettingContent-ms attachments and downloads. Identify the recipients and triage their endpoints first.

    2. Runbook step 2

      Mitigation layers

      • Endpoint hardening (ASR): Enable the Defender ASR rule "Block all Office applications from creating child processes" (GUID D4F940AB-401B-4EFC-AADC-AD5F3C50688A) in block mode. This vector was commonly triggered through objects embedded in Office documents.
      • Application control: Use AppLocker or WDAC to prevent execution from user-writable paths (%TEMP%, %APPDATA%, Downloads, INetCache). The DeepLink element of a weaponised file typically points to cmd.exe, powershell.exe or a dropped binary.
      • Office configuration: Use GPO to block OLE Package objects and enforce Protected View for internet-origin files. Make sure archives cannot strip Mark-of-the-Web by using extraction tools that propagate MOTW.
      • Network/proxy: Add download filters for the .settingcontent-ms extension and for XML content containing <PCSettings> with a <DeepLink> element. Enable IPS signatures that cover SettingContent-ms objects embedded in OLE streams.
      • IAM/least privilege: Keep end users off local admin, so that successful user-context code execution does not translate into system-level control.

    3. Runbook step 3

      Detection rules

      • Sysmon EID 11 / Defender DeviceFileEvents: Creation of *.SettingContent-ms outside C:\Windows\ImmersiveControlPanel\. KQL: DeviceFileEvents | where FileName endswith ".settingcontent-ms" and FolderPath !startswith @"C:\Windows\ImmersiveControlPanel"
      • Sysmon EID 1 / Security 4688: An Office application or browser (winword.exe, excel.exe, outlook.exe, msedge.exe, chrome.exe) spawning cmd.exe, powershell.exe, mshta.exe, rundll32.exe or regsvr32.exe. Sigma shape: ParentImage|endswith: [\winword.exe, \excel.exe] AND Image|endswith: [\cmd.exe, \powershell.exe].
      • Mail gateway / proxy logs: Attachments or HTTP downloads ending in .settingcontent-ms, or Office files carrying an embedded object of that type. SPL: index=proxy uri_path="*.settingcontent-ms*" | stats count by src_ip, user, uri
      • Content scanning (YARA/file scan): XML files containing <PCSettings> together with a <DeepLink> that references cmd, powershell or any path outside %windir%.
      • EDR network telemetry: Outbound connections from powershell.exe or unknown binaries in %TEMP% shortly after a document is opened. Correlate them with the preceding process tree.

    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

    A remote code execution vulnerability exists when the Windows Shell does not properly validate file paths, aka "Windows Shell Remote Code Execution Vulnerability." This affects Windows 10 Servers, Windows 10.

    Source: NVD (NIST), cvelistv5, CISA KEV Catalog

    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 1803 for 32-bit Systems
    • Version 1703 for 32-bit Systems
    • Version 1709 for 32-bit Systems
    • Version 1803 for x64-based Systems
    • Version 1703 for x64-based Systems
    • Version 1709 for x64-based Systems
    • —
    • —
    • —
    • —
    • —
    • —
    MicrosoftWindows 10 Servers
    • version 1803 (Server Core Installation)
    • version 1709 (Server Core Installation)
    • —
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Windowsmicrosoftwindows_10_1703—
    Windowsmicrosoftwindows_10_1709—
    Windowsmicrosoftwindows_10_1803—
    Windowsmicrosoftwindows_server_1709—
    Windowsmicrosoftwindows_server_1803—

    Weakness classes (CWE)

    • CWE-20Improper Input Validation

      Class

      The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

      Entry at MITRE CWE-20

    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

    • portal.msrc.microsoft.comen-US/security-guidance/advisory/CVE-2018-8414x_refsource_CONFIRM, Patch, Vendor advisory
    • securityfocus.com105016Vulnerability database, x_refsource_BID, Broken link, Third-party advisory, Vulnerability database
    • securitytracker.com1041458Vulnerability database, x_refsource_SECTRACK, Broken link, Third-party advisory, Vulnerability database
    • cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2018-8414government-resource, US government resource
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