CriticalCVE-2018-8453

    Microsoft Win32k Privilege Escalation Vulnerability (CVE-2018-8453)

    Published In CISA KEV since Sources: CVE.org

    What is affected, what to do

    An elevation of privilege vulnerability exists in Windows when the Win32k component fails to properly handle objects in memory, aka "Win32k Elevation of Privilege Vulnerability." This affects Windows 7, Windows Server 2012 R2, Windows RT 8.1, Windows Server 2008, Windows Server 2019, Windows Server 2012, Windows 8.1, Windows Server 2016, Windows Server 2008 R2, Windows 10, Windows 10 Servers.

    The vulnerability is being actively exploited; treat it as a priority. CISA lists it as used in ransomware campaigns. 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 7 eq 32-bit Systems Service Pack 1..32-bit Systems Service Pack 1
    • Microsoft Windows 7 eq x64-based Systems Service Pack 1..x64-based Systems Service Pack 1
    • Microsoft Windows Server 2012 R2 eq (Server Core installation)..(Server Core installation)
    • Microsoft Windows RT 8.1 eq Windows RT 8.1..Windows RT 8.1
    • Microsoft Windows Server 2008 eq 32-bit Systems Service Pack 2..32-bit Systems Service Pack 2
    • Microsoft Windows Server 2008 eq 32-bit Systems Service Pack 2 (Server Core installation)..32-bit Systems Service Pack 2 (Server Core installation)
    • Microsoft Windows Server 2008 eq Itanium-Based Systems Service Pack 2..Itanium-Based Systems Service Pack 2
    • Microsoft Windows Server 2008 eq x64-based Systems Service Pack 2..x64-based Systems Service Pack 2
    • Microsoft Windows Server 2008 eq x64-based Systems Service Pack 2 (Server Core installation)..x64-based Systems Service Pack 2 (Server Core installation)
    • Microsoft Windows Server 2019 eq (Server Core installation)..(Server Core installation)
    • Microsoft Windows Server 2012 eq (Server Core installation)..(Server Core installation)
    • Microsoft Windows 8.1 eq 32-bit systems..32-bit systems
    • Microsoft Windows 8.1 eq x64-based systems..x64-based systems
    • Microsoft Windows Server 2016 eq (Server Core installation)..(Server Core installation)
    • Microsoft Windows Server 2008 R2 eq Itanium-Based Systems Service Pack 1..Itanium-Based Systems Service Pack 1
    • Microsoft Windows Server 2008 R2 eq x64-based Systems Service Pack 1..x64-based Systems Service Pack 1
    • Microsoft Windows Server 2008 R2 eq x64-based Systems Service Pack 1 (Server Core installation)..x64-based Systems Service Pack 1 (Server Core installation)
    • Microsoft Windows 10 eq 32-bit Systems..32-bit Systems
    • Microsoft Windows 10 eq Version 1607 for 32-bit Systems..Version 1607 for 32-bit Systems
    • Microsoft Windows 10 eq Version 1607 for x64-based Systems..Version 1607 for x64-based Systems
    • 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
    • Microsoft Windows 10 eq Version 1809 for 32-bit Systems..Version 1809 for 32-bit Systems
    • Microsoft Windows 10 eq Version 1809 for x64-based Systems..Version 1809 for x64-based Systems
    • Microsoft Windows 10 eq x64-based Systems..x64-based Systems
    • 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)

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

    Metrics

    7.8

    Priority

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

    Source: NVD, CVSS v3

    7.8

    CVSS v3

    Severity High on the scale from 0 to 10.

    Source: CVE.org

    70.0 %

    EPSS score

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

    Source: FIRST EPSS, percentile 99.37

    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
    243.00 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
    7.8 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
    7.8
    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
    70.0 %
    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
    99.37
    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 20 January 2022

    Response and mitigation

    Why act now?

    Prioritisation rationale

    This bug is a dependable link in attack chains: after phishing or a drive-by compromise it lifts an ordinary, unprivileged user context to SYSTEM, enabling credential dumping, tampering with security tooling and lateral movement. CISA flags its use in ransomware campaigns, its exploitation likelihood is rated very high, and public exploit code puts it within reach of low-skill operators. Despite the local attack vector, impact on confidentiality, integrity and availability is total. Treat it as critical wherever you still run a meaningful legacy estate (Windows 7, Server 2008/2012, early Windows 10 builds) or shared terminal-server environments; fully current fleets should simply verify patch compliance and keep the detection rules live.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Verify patch level and deploy the update: Microsoft fixed this vulnerability in the October 2018 Patch Tuesday security release; any later cumulative update or Monthly Rollup includes the fix. Look up the exact KB IDs per Windows version in the Microsoft Security Update Guide entry for CVE-2018-8453. Treat any host without an October 2018 or later update level as vulnerable.
      • Inventory legacy systems: Query CMDB, WSUS/Intune or the Defender for Endpoint inventory specifically for Windows 7, Windows 8.1, Server 2008/2008 R2 and old Windows 10 builds (1507–1809). Flag hosts without current patch support (end of life, no ESU) as high-risk and prioritise isolation or replacement.
      • Patch multi-user systems first: RDS/terminal servers, Citrix hosts, jump hosts and VDI pools where many users can run local code. A single compromised session there yields SYSTEM on the whole host.
      • Hunt for compromise on unpatched hosts: Run an EDR query for SYSTEM-integrity processes spawned by user-context parents (see detection rules). On hits, isolate the host, capture memory and rotate any credentials cached locally, especially privileged domain accounts.
      • Close the initial-access vectors: This is a local privilege escalation chained after phishing, macro or browser exploits. Block internet-sourced Office macros and tighten mail attachment filtering for executables and scripts.

    2. Runbook step 2

      Mitigation layers

      • Application control (endpoint hardening): Configure WDAC or AppLocker to deny execution from user-writable paths (%TEMP%, %APPDATA%, %USERPROFILE%\Downloads). The exploit binary has to run locally — blocking execution breaks the chain.
      • Attack Surface Reduction: Enable Defender ASR rules including "Block executable files from running unless they meet a prevalence, age, or trusted list criterion", "Block Office applications from creating child processes" and "Block credential stealing from the Windows local security authority subsystem (lsass.exe)".
      • Limit post-escalation blast radius (IAM): Enable LSA protection (RunAsPPL) and Credential Guard, deploy LAPS for local admin accounts, and keep privileged domain accounts off workstations via a tiering model, so SYSTEM access does not yield reusable domain credentials.
      • Network segmentation: Move unpatchable legacy hosts into a dedicated VLAN and allow inbound SMB (445/tcp), RDP (3389/tcp) and WinRM (5985–5986/tcp) only from designated admin systems to contain lateral movement after a successful escalation.
      • Least privilege for end users: Restrict "Allow log on locally" and "Allow log on through Remote Desktop Services" on servers via GPO to required groups only; no interactive sessions for service accounts.

    3. Runbook step 3

      Detection rules

      • Integrity-level jump in the process tree (MDE/KQL): DeviceProcessEvents | where ProcessIntegrityLevel == "System" and InitiatingProcessIntegrityLevel in ("Medium","Low") and InitiatingProcessFileName !in~ ("msiexec.exe","consent.exe") — the classic token-stealing pattern following a kernel exploit.
      • Sysmon EID 1 / Security EID 4688: cmd.exe, powershell.exe or rundll32.exe running as NT AUTHORITY\SYSTEM whose parent runs under a regular user account and is not services.exe, wininit.exe or svchost.exe. Sigma shape: selection: User|contains: 'SYSTEM' + filter: ParentImage|endswith: ['\services.exe','\wininit.exe','\svchost.exe'], correlated with a non-SYSTEM parent user.
      • Failed exploitation attempts: System Event ID 1001 (BugCheck) or WER entries referencing win32k.sys/win32kfull.sys. Clusters of blue screens on clients with no hardware fault are a strong hint of unstable kernel exploits.
      • Unsigned binaries from user paths: Sysmon EID 1 or EID 7 with Image|contains: '\AppData\' or '\Temp\' and Signed = false, followed within seconds by a SYSTEM child process or Security EID 4672 (special privileges assigned) with no matching admin logon.
      • Follow-on activity: Access to lsass.exe (Sysmon EID 10 with GrantedAccess 0x1010/0x1410), new service installs (System EID 7045) or new local admin accounts (Security EID 4720/4732) shortly after suspicious process execution.

    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

    An elevation of privilege vulnerability exists in Windows when the Win32k component fails to properly handle objects in memory, aka "Win32k Elevation of Privilege Vulnerability." This affects Windows 7, Windows Server 2012 R2, Windows RT 8.1, Windows Server 2008, Windows Server 2019, Windows Server 2012, Windows 8.1, Windows Server 2016, Windows Server 2008 R2, Windows 10, Windows 10 Servers.

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

    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 1809 for x64-based Systems
    • 32-bit Systems
    • Version 1803 for 32-bit Systems
    • x64-based Systems
    • Version 1703 for 32-bit Systems
    • Version 1809 for 32-bit Systems
    • Version 1709 for 32-bit Systems
    • Version 1803 for x64-based Systems
    • Version 1607 for 32-bit Systems
    • Version 1703 for x64-based Systems
    • Version 1709 for x64-based Systems
    • Version 1607 for x64-based Systems
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    MicrosoftWindows 10 Servers
    • version 1803 (Server Core Installation)
    • version 1709 (Server Core Installation)
    • —
    • —
    MicrosoftWindows 7
    • 32-bit Systems Service Pack 1
    • x64-based Systems Service Pack 1
    • —
    • —
    MicrosoftWindows 8.1
    • x64-based systems
    • 32-bit systems
    • —
    • —
    MicrosoftWindows RT 8.1
    • Windows RT 8.1
    • —
    MicrosoftWindows Server 2008
    • x64-based Systems Service Pack 2 (Server Core installation)
    • 32-bit Systems Service Pack 2 (Server Core installation)
    • 32-bit Systems Service Pack 2
    • x64-based Systems Service Pack 2
    • Itanium-Based Systems Service Pack 2
    • —
    • —
    • —
    • —
    • —
    MicrosoftWindows Server 2008 R2
    • x64-based Systems Service Pack 1
    • Itanium-Based Systems Service Pack 1
    • x64-based Systems Service Pack 1 (Server Core installation)
    • —
    • —
    • —
    MicrosoftWindows Server 2012
    • (Server Core installation)
    • —
    MicrosoftWindows Server 2012 R2
    • (Server Core installation)
    • —
    MicrosoftWindows Server 2016
    • (Server Core installation)
    • —
    MicrosoftWindows Server 2019
    • (Server Core installation)
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Windowsmicrosoftwindows_10_1507—
    Windowsmicrosoftwindows_10_1607—
    Windowsmicrosoftwindows_10_1703—
    Windowsmicrosoftwindows_10_1709—
    Windowsmicrosoftwindows_10_1803—
    Windowsmicrosoftwindows_10_1809—
    Windowsmicrosoftwindows_7—
    Windowsmicrosoftwindows_8.1—
    Windowsmicrosoftwindows_rt_8.1—
    Windowsmicrosoftwindows_server_1709—
    Windowsmicrosoftwindows_server_1803—
    Windowsmicrosoftwindows_server_2008r2
    Windowsmicrosoftwindows_server_2008—
    Windowsmicrosoftwindows_server_2012r2
    Windowsmicrosoftwindows_server_2012—
    Windowsmicrosoftwindows_server_2016—
    Windowsmicrosoftwindows_server_2019—

    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
    Packet StormMicrosoft Windows NtUserSetWindowFNID Win32k User Callback (opens in a new tab)packetstormsecurity.comPoC (publicly reported)reported, not verified—

    References & sources

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