IRONSMITHINTEL
HIGHCVSS7.0
|
Actively Exploited
|CISA KEV|CVE-2018-8120|Auth: low — authenticated user|Reboot: required|Manual only

KB4103712: Windows Server Security Update (May 2018)

A privilege escalation vulnerability exists in Windows when the Win32k component fails to properly handle objects in memory.

Published May 9, 2018 · Updated May 16, 2026
Why patchRisk explained in plain English
Worst-case scenarioIf unpatched

A local attacker, with a low-privilege account, can achieve full data confidentiality loss, arbitrary modification of data, complete denial of service or system unavailability. CISA has confirmed use of this vulnerability in known ransomware campaigns — treat as high priority for remediation. Federal agencies are required to remediate by 2022-04-05 under CISA BOD 22-01.

How the attack worksNo clicks needed

This is a Software Vulnerability (CWE-404) (CWE-404) vulnerability in Microsoft Win32k. 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 Server 2008, Windows 7, Windows Server 2008 R2. This CVE ID is unique from CVE-2018-8124, CVE-2018-8164, CVE-2018-8166. Exploitation requires local access, higher attack complexity, a low-privilege authenticated account, and no user interaction required.

Am I affected?Quick check

Probably yes if any of these apply:

●IT Security
●Running windows 7: -; windows server 2008: -, r2
Fixed inKB4103712, KB4103718, KB4131188 (applies to 10 product versions)
Real-world incidentsWhat we've seen

Used in known ransomware campaigns. Threat-research write-up: https://www.exploit-db.com/exploits/45653/

How to patch

Manual download

For air-gapped servers or out-of-band deployment. Microsoft Update Catalog returns every OS-version variant of this update.

↗ Microsoft Update CatalogKB4103712

Manual remediation steps

Apply the Microsoft Security Update

Microsoft has released an official security update that fixes this vulnerability.

Required KB Updates

    1
    KB4103712 — https://support.microsoft.com/help/4103712
    1
    KB4103718 — https://support.microsoft.com/help/4103718
    1
    KB4131188 — https://support.microsoft.com/help/4131188

Supersedes: KB4093118, KB4093224

Affected Products

    1
    Windows 7 for 32-bit Systems Service Pack 1
    1
    Windows 7 for x64-based Systems Service Pack 1
    1
    Windows Server 2008 R2 for Itanium-Based Systems Service Pack 1
    1
    Windows Server 2008 R2 for x64-based Systems Service Pack 1
    1
    Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation)
    1
    Windows Server 2008 for 32-bit Systems Service Pack 2
    1
    Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation)
    1
    Windows Server 2008 for Itanium-Based Systems Service Pack 2
    1
    Windows Server 2008 for x64-based Systems Service Pack 2
    1
    Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation)

Installation Methods

Windows Update (recommended)

1
Settings → Windows Update → Check for updates
2
The security update is offered if your system is in scope
3
Restart when prompted — a reboot IS required to complete the install

Microsoft Update Catalog (manual download)

1
Open https://catalog.update.microsoft.com
2
Search for KB4103712
3
Download the package matching your OS architecture and Windows build
4
Run the .msu installer with administrator privileges
5
Restart when prompted

WSUS / SCCM / Intune

Approve KB4103712 for the affected products in your update management console.

Microsoft Download Center Links

    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB4103712
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB4103718
    1
    https://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB4131188

Verification

Confirm the update is installed:

Get-HotFix | Where-Object { $_.HotFixID -in @('KB4103712','KB4103718','KB4131188') }

References

    1
    Microsoft Security Response Center: https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2018-8120
    1
    NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2018-8120
    1
    CISA KEV: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2018-8120

Discovery Credit

Anton Cherepanov, Senior Malware Researcher of ESET

PowerShell automationComing soon

No tested PowerShell script for this entry yet. We’re prioritising automation based on user demand.

References

↗ CVE-2018-8120↗ MSRC Advisory↗ NVD↗ KBKB4103712