Microsoft Win32k Privilege Escalation Vulnerability (CVE-2015-2360)
Published In CISA KEV since Sources: CVE.org
What is affected, what to do
win32k.sys in the kernel-mode drivers in Microsoft Windows Server 2003 SP2 and R2 SP2, Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8, Windows 8.1, Windows Server 2012 Gold and R2, and Windows RT Gold and 8.1 allows local users to gain privileges or cause a denial of service (memory corruption) via a crafted application, aka "Win32k Elevation of Privilege Vulnerability."
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 2003
eq r2..r2 - Microsoft Windows Server 2008
eq r2..r2 - Microsoft Windows Server 2012
eq r2..r2
- Microsoft Windows Server 2003
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Metrics
8.8
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: Vendor (CNA), CVSS v3
8.8
CVSS v3
Severity High on the scale from 0 to 10.
Source: CVE.org
14.8 %
EPSS score
Elevated — model estimates 10-50% exploitation likelihood.
Source: FIRST EPSS, percentile 96.7
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- 218.78 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- 14.8 %
- 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- 96.7
- 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
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-416
Response and mitigation
Why act now?
Prioritisation rationale
This CVE sits on KEV because Win32k LPEs have been a reliable second-stage building block in exploit chains for years — typically chained after phishing or browser initial access to escalate a standard user to SYSTEM. The exploitation likelihood is in the upper percentile band, which raises operational urgency even without documented ransomware use. For NIS2-regulated operators the risk concentrates on multi-user platforms (RDS, Citrix, admin jump hosts) and on legacy OS without a regular patch path; residual-risk ratings there should be tied to the quality of isolation. Exploitation requires local code execution context, so pure perimeter servers with no interactive users rank below fat clients and shared session hosts.
Runbook step 1
Immediate response (0-24 h)
- Deploy Microsoft update MS15-061 (June 2015) on all affected Windows hosts — this is the vendor fix for win32k.sys. Prioritise multi-user systems (RDS/Terminal servers, jump hosts, VDI, shared workstations) since the flaw yields local privilege escalation.
- Identify legacy systems with no available patch (Windows Server 2003, Vista, Windows 8, Windows RT) and isolate them: network segmentation, revoke interactive logon rights, trigger a migration plan to a supported OS.
- Inventory local and service accounts with interactive-logon rights on affected hosts — any account that can log on locally is a potential pivot to SYSTEM.
- Verify patch compliance via WSUS/SCCM/Intune or Tenable/Qualys; move non-compliant hosts into a dedicated change ticket with a 72 h SLA.
- On Terminal/Citrix servers, review AppLocker or WDAC policies: only approved binaries may launch from user-writable paths (%TEMP%, %APPDATA%, Downloads) to block exploit droppers.
Runbook step 2
Mitigation layers
- Network: place legacy hosts in dedicated VLANs with strict ingress/egress ACLs; permit SMB (445), RDP (3389) and WinRM (5985/5986) only from the admin jump-host range.
- Endpoint hardening: enable EMET or Exploit Guard (ASR rules), especially „Block credential stealing from LSASS" and „Block executable content from email/webmail", reducing post-exploit payload success.
- IAM/least privilege: strip interactive logon from standard users on server systems; roll out LAPS for local administrator passwords; use Protected Users Group and Credential Guard (Windows 10 / Server 2016+) where available.
- Application control: AppLocker rules for executables, DLLs, scripts and installers with default-deny in user-writable paths — this neutralises most public PoCs for Win32k exploits.
- Monitoring: deploy Sysmon with SwiftOnSecurity or Olaf Hartong config on all legacy and multi-user hosts if not already present — no telemetry, no detection.
- Compensating controls for end-of-life systems: check ESU licence availability; otherwise apply virtual patching via HIPS/EDR policy and permit access only through a session broker with recording.
Runbook step 3
Detection rules
- Sysmon EID 1 (Process Create) with ParentImage in a user-writable path spawning a child process at integrity level „System" — the classic LPE signature. KQL shape:
DeviceProcessEvents | where InitiatingProcessFolderPath has_any ("\\Temp\\","\\AppData\\") and ProcessIntegrityLevel == "System". - Windows Event ID 4672 („Special privileges assigned to new logon") for accounts that normally never receive SeDebugPrivilege/SeTcbPrivilege, correlated with a preceding 4624 logon type 2/10.
- Bluescreen/Bugcheck events (System log EID 1001, bugcheck 0x3B or 0x50) referencing Win32k modules — failed exploit attempts frequently trigger memory-corruption crashes.
- EDR telemetry: unusual callers invoking
NtUserMessageCall,NtGdiBitBltor related Win32k syscalls from Office children, browser renderers or script hosts. Sigma shape: process image not inexplorer.exe|csrss.exe|winlogon.exewith elevated Win32k syscall frequency. - Sysmon EID 7 (Image Load) baseline deviation: unusual DLLs loaded into
csrss.exeor other session-0 processes originating from user context.
- Sysmon EID 1 (Process Create) with ParentImage in a user-writable path spawning a child process at integrity level „System" — the classic LPE signature. KQL shape:
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
win32k.sys in the kernel-mode drivers in Microsoft Windows Server 2003 SP2 and R2 SP2, Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8, Windows 8.1, Windows Server 2012 Gold and R2, and Windows RT Gold and 8.1 allows local users to gain privileges or cause a denial of service (memory corruption) via a crafted application, aka "Win32k Elevation of Privilege Vulnerability."
Source: NVD (NIST), cvelistv5, CISA KEV Catalog, CVE.org (MITRE)
Vendors and products
- Microsoft Microsoft Windows 7
- Microsoft Microsoft Windows 8 Professional Edition
- Microsoft Microsoft Windows 8.1
- Microsoft Microsoft Windows RT Gold
- Microsoft Microsoft Windows RT 8.1
- Microsoft Microsoft Windows Server 2003
- Microsoft Microsoft Windows Server 2008
- Microsoft Microsoft Windows Server 2012
- Microsoft Microsoft Windows Vista Gold on X64
Affected operating systems
| Windows | microsoft | windows_7 | — |
| Windows | microsoft | windows_8 | — |
| Windows | microsoft | windows_8.1 | — |
| Windows | microsoft | windows_rt | — |
| Windows | microsoft | windows_rt_8.1 | — |
| Windows | microsoft | windows_server_2003 | r2 |
| Windows | microsoft | windows_server_2003 | — |
| 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 | — |
Weakness classes (CWE)
CWE-416Use After Free
Variant
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
Entry at MITRE CWE-416
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 |
References & sources
- securitytracker.com1032525Vulnerability database, x_refsource_SECTRACK, Broken link, Third-party advisory, Vulnerability database
- securityfocus.com75025Vulnerability database, x_refsource_BID, Broken link, Third-party advisory, Vulnerability database
- docs.microsoft.comMS15-061Vendor advisory, x_refsource_MS, Patch, Vendor advisory
- cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2015-2360government-resource, US government resource
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<a href="https://intel.neosec.eu/en/cve/CVE-2015-2360"><img src="https://intel.neosec.eu/badge/cve/CVE-2015-2360.svg?lang=en" alt="CVE-2015-2360 – NEOSEC Intel" height="20"></a>