Microsoft Windows Win32k Kernel-Mode Driver Elevation of Privilege Vulnerability (CVE-2016-0165, MS16-039)
Executive & SecOps Summary
SECOPS ASSESSMENTWindows Vista SP2, 7 SP1, 8.1, 10, and Windows Server 2008/2012 legacy operating systems
Local attackers can execute a specially crafted application to gain SYSTEM-level privileges and fully compromise the host
Apply the official Microsoft security update (MS16-039) immediately and restrict local execution permissions on unpatched systems
Affected Products & Version Scope
Remediation & Live Workaround Commands
PATCH & WORKAROUND1. Official Patch & Version Upgrade Commands
Apply the MS16-039 security update. On modern or managed Windows environments, ensure the Windows Update service is running and install the relevant KB packages.
# Install PSWindowsUpdate module and apply the specific security updates
Install-Module PSWindowsUpdate -Force -Verbose
Get-WindowsUpdate -KBArticleID KB3148522, KB3148528 -Install -AcceptAll -AutoReboot2. Temporary Workaround & Hardening Configuration
If immediate patching is not feasible, restrict execution privileges for non-administrative users and enforce AppLocker policies to prevent unauthorized binaries from executing.
# Enable and start the Application Identity service for AppLocker
Set-Service -Name AppIDSvc -StartupType Automatic
Start-Service -Name AppIDSvc3. Log Audit & IoC Verification Commands
Verify the patch status by checking the file version of win32k.sys.
# Check the file version of win32k.sys to verify patch level
$sysPath = '${env:SystemRoot}\System32\win32k.sys'
if (Test-Path $sysPath) {
$fileVersion = (Get-Item $sysPath).VersionInfo.FileVersion
Write-Host 'Current win32k.sys Version:' $fileVersion
# Compare this version against the minimum patched version for your OS build.
} else {
Write-Warning 'win32k.sys file not found.'
}Block Kernel Privilege Escalation & Ransomware Payloads Before You Can Reboot
Protect unpatched Windows, Linux, and macOS workloads against in-memory exploitation and lateral movement with autonomous EDR.
Technical Root Cause & Exploitation Mechanics
1. Vulnerability Overview & Root Cause
This vulnerability (CVE-2016-0165) is an elevation of privilege (EoP) vulnerability in the Windows kernel-mode driver (win32k.sys). The root cause lies in the improper handling of objects in memory by the graphics and window management components of win32k.sys. When processing specific system calls, the driver fails to validate memory structures, leading to memory corruption that allows arbitrary write operations in kernel space.
2. Exploitation Mechanics & Attack Scenario
To exploit this vulnerability, an attacker must first gain local access to the target system with low-privilege user rights. The attacker then executes a crafted application designed to trigger the memory corruption vulnerability within win32k.sys via specific GDI or window management APIs. By corrupting kernel memory structures, the exploit overwrites the security token of the calling process with the SYSTEM token, effectively elevating the attacker's privileges to the highest level.
3. Infrastructure & Business Impact
As a vulnerability listed in the CISA KEV catalog, CVE-2016-0165 has been actively exploited in the wild. Local privilege escalation is a critical phase in advanced persistent threat (APT) campaigns, enabling attackers to bypass endpoint detection, perform lateral movement, deploy ransomware, and establish persistent backdoors, posing a severe threat to enterprise infrastructure.
Official Vendor Advisories & References
The kernel-mode driver in Microsoft Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8.1, Windows Server 2012 Gold and R2, Windows RT 8.1, and Windows 10 Gold and 1511 allows local users to gain privileges via a crafted application, aka "Win32k Elevation of Privilege Vulnerability," a different vulnerability than CVE-2016-0143 and CVE-2016-0167.
Frequently Asked SecOps Questions (CVE-2016-0165)
FAQQ1. How critical is CVE-2016-0165 and is it actively exploited in the wild?
CVE-2016-0165 is rated CVSS 7.8 (HIGH) with a 30-day EPSS exploitation probability of 13.7%. It is listed in the CISA Known Exploited Vulnerabilities (KEV) catalog, requiring immediate emergency remediation.
Q2. Which vendors and products are affected by CVE-2016-0165?
Primary impacted vendors include microsoft across windows, windows_server. Scope summary: Windows Vista SP2, Windows Server 2008 SP2/R2 SP1, Windows 7 SP1, Windows 8.1, Windows Server 2012 Gold/R2, Windows RT 8.1, Windows 10 Gold/1511
Q3. What temporary mitigations or workarounds exist for CVE-2016-0165 before patching?
[Mitigation] Apply the official Microsoft security update (MS16-039) immediately and restrict local execution permissions on unpatched systems Follow the CLI remediation commands and interactive SecOps checklist on this page to restrict exposure prior to your maintenance window.
Generate an Internal Engineering Notice or CISO Report for CVE-2016-0165
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