Microsoft Win32k Privilege Escalation Vulnerability (CVE-2016-0165)
Published In CISA KEV since Sources: CVE.org
What is affected, what to do
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.
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 Server 2008
eq r2..r2 - Microsoft Windows Server 2012
eq r2..r2
- Microsoft Windows Server 2008
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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
13.7 %
EPSS score
Elevated — model estimates 10-50% exploitation likelihood.
Source: FIRST EPSS, percentile 96.5
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- 213.47 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- 13.7 %
- 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- 96.5
- 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 10 February 2025
Response and mitigation
Why act now?
Prioritisation rationale
CVE-2016-0165 is a local privilege escalation in the Win32k kernel-mode driver. It requires no prior privileges, only user execution of a crafted application. Attackers use Win32k bugs of this kind as a second stage after phishing or browser exploits, lifting a standard-user or sandboxed foothold to SYSTEM. Exploitation likelihood is rated high, and CISA reports no known ransomware campaign use. The real exposure is unpatched legacy Windows, typically OT HMIs, lab PCs and line-of-business servers in KRITIS environments; patch or isolate those immediately. On a well-maintained, current Windows fleet, verifying patch state is sufficient.
Runbook step 1
Immediate response (0-24 h)
- Identify affected assets: Use CMDB, SCCM/Intune or EDR to enumerate every host running Windows Vista SP2, Windows 7 SP1, Windows 8.1/RT 8.1, Windows 10 1507/1511, Windows Server 2008 SP2/R2 SP1 or Windows Server 2012/2012 R2. Most of these are out of vendor support, so treat them as high-risk legacy systems.
- Apply the security update: A patch is available from the vendor — look up the exact version in the vendor advisory (Microsoft Security Update Guide entry for CVE-2016-0165). Verify the
win32k.sysfile version against the advisory, and confirm the cumulative rollup level on any ESU-covered hosts. - Isolate legacy hosts that cannot be patched: Move them to a dedicated legacy VLAN, block interactive logon by standard users, and remove internet access and mail clients.
- Hunt on exposed, unpatched endpoints: On unpatched workstations used for email and browsing, look for SYSTEM processes with a user-context parent (see Detection rules). This bug is typically chained as the second stage after a phishing or browser compromise.
- Rotate privileged credentials on any hit: Reset local admin passwords (LAPS). Treat cached domain credentials on the host as compromised and reset the affected accounts.
Runbook step 2
Mitigation layers
- Application control (endpoint): Configure WDAC or AppLocker to block EXE/DLL execution from user-writable paths (
%APPDATA%,%TEMP%,%USERPROFILE%\Downloads,C:\Users\Public). The exploit depends on running a crafted local binary, so blocking that execution removes its foothold. - Constrain the initial vector: Block internet-sourced Office macros via GPO. Enable ASR rules where the Defender build supports them, such as "Block executable content from email client and webmail" and "Block Office applications from creating child processes". Enforce sandboxed, current browsers.
- Network segmentation: Filter outbound SMB (445/tcp), RDP (3389/tcp) and WinRM (5985/5986/tcp) from the legacy VLAN towards server segments and domain controllers, allowing only what operations strictly require. This contains lateral movement after a successful privilege escalation.
- Least privilege and tiering: Deny Tier-0/Tier-1 logons on affected hosts via the "Deny log on locally/through RDP" GPO settings. Credential Guard is not available on these legacy builds, so SYSTEM access means direct access to LSASS.
- Migration path: Because these platforms are largely end-of-life, moving to a supported Windows release is the only durable fix. Newer releases also support per-process Win32k system call filtering through Exploit Protection.
- Application control (endpoint): Configure WDAC or AppLocker to block EXE/DLL execution from user-writable paths (
Runbook step 3
Detection rules
- Sysmon EID 1 / Windows 4688 – integrity jump: Alert on a process with
IntegrityLevel=SystemorUser=NT AUTHORITY\SYSTEMwhose parent runs as a standard user. Exclude legitimate service hosts such asservices.exeandsvchost.exe. KQL:DeviceProcessEvents | where ProcessIntegrityLevel == "System" and InitiatingProcessIntegrityLevel in ("Medium","Low") - Suspicious process ancestry (EDR):
cmd.exe,powershell.exeorrundll32.exerunning as SYSTEM whose chain traces back towinword.exe,excel.exe,outlook.exe, a browser, or an unsigned EXE in%TEMP%/%APPDATA%. - Failed exploitation attempts: Event ID 1001 (BugCheck) or Kernel-Power Event ID 41 with a crash in
win32k.syson clients with no known hardware issues. Clusters of these crashes point to unstable exploit runs. - Post-exploitation follow-on: Windows 4672 (special privileges assigned) or Sysmon EID 10 showing a non-standard process accessing
lsass.exe(GrantedAccess0x1010/0x1410) shortly after execution from a user path. Also watch Sysmon EID 13 for new services or Run keys created by user-context processes. - Sigma shape:
selection: IntegrityLevel: System, ParentImage|contains: ['\Users\', '\AppData\', '\Temp\']→ level high.
- Sysmon EID 1 / Windows 4688 – integrity jump: Alert on a process with
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
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.
Source: NVD (NIST), cvelistv5, CISA KEV Catalog, CVE.org (MITRE)
Vendors and products
Affected operating systems
| Windows | microsoft | windows_10_1507 | — |
| Windows | microsoft | windows_10_1511 | — |
| Windows | microsoft | windows_7 | — |
| Windows | microsoft | windows_8.1 | — |
| Windows | microsoft | windows_rt_8.1 | — |
| Windows | microsoft | windows_server_2008 | r2 |
| Windows | microsoft | windows_server_2008 | — |
| Windows | microsoft | windows_server_2012 | r2 |
| Windows | microsoft | windows_server_2012 | — |
| Windows | microsoft | windows_vista | — |
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.
| CISA KEV Catalog | CISA Known Exploited Vulnerability (opens in a new tab)cisa.gov | actively exploited | |
| Exploit-DB | EDB-ID 44480 (opens in a new tab)exploit-db.com | PoC (publicly reported)reported, not verified | — |
References & sources
- securitytracker.com1035529Vulnerability database, x_refsource_SECTRACK, Broken link, Third-party advisory, Vulnerability database
- exploit-db.com44480Exploit, x_refsource_EXPLOIT-DB, Product, Third-party advisory, Vulnerability database
- securitytracker.com1035532Vulnerability database, x_refsource_SECTRACK, Broken link, Third-party advisory, Vulnerability database
- docs.microsoft.comMS16-039Vendor advisory, x_refsource_MS, Patch, Vendor advisory
- cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2016-0165government-resource, US government resource
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<a href="https://intel.neosec.eu/en/cve/CVE-2016-0165"><img src="https://intel.neosec.eu/badge/cve/CVE-2016-0165.svg?lang=en" alt="CVE-2016-0165 – NEOSEC Intel" height="20"></a>