Microsoft Win32k Privilege Escalation Vulnerability (CVE-2018-8120)
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 Server 2008, Windows 7, Windows Server 2008 R2. This CVE ID is unique from CVE-2018-8124, CVE-2018-8164, CVE-2018-8166.
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 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 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 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 Server 2008
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Metrics
7.0
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: NVD, CVSS v3
7.0
CVSS v3
Severity High on the scale from 0 to 10.
Source: CVE.org
73.3 %
EPSS score
High — model estimates ≥ 50% chance of real-world exploitation within 30 days.
Source: FIRST EPSS, percentile 99.46
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- 239.14 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- 7.0 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- 7.0
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- 73.3 %
- 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- 99.46
- 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 14 March 2022
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-404
Response and mitigation
Why act now?
Prioritisation rationale
This CVE sits on KEV because it has become the default second-stage building block for commodity ransomware campaigns (Magniber, GandCrab derivatives) and red-team toolkits — the exploit is stable, publicly available and targets a very widespread legacy OS. The CVSS vector shows local execution with low privileges, but in real attack chains the initial user-context foothold comes from phishing, and Win32k then reliably delivers SYSTEM. Exploitation likelihood per EPSS is extremely high. Rate HIGH priority for any legacy Windows asset reachable by users or exposed internet services; isolated, well-segmented OT hosts without user interaction may be rated MEDIUM, provided the segmentation is audited.
Runbook step 1
Immediate response (0-24 h)
- Deploy the Microsoft May 2018 Patch Tuesday fix on every affected host: KB4103718 (Windows 7 / Server 2008 R2 Monthly Rollup), KB4103712 (Security-only), KB4103730 (Server 2008 SP2). This is the only durable remediation.
- Filter the asset inventory for Windows 7, Windows Server 2008 SP2 and Windows Server 2008 R2; flag any host without Extended Security Updates (ESU) as end-of-life and prioritise for isolation or migration.
- Audit local accounts on these hosts: because the exploit requires local code execution, restrict interactive logon and RDP to hardened jump hosts; review service accounts holding SeAssignPrimaryTokenPrivilege or SeDebugPrivilege.
- For legacy hosts that cannot be patched (OT gateways, production HMIs): place into a dedicated VLAN, block all inbound SMB/RDP from user networks, revoke internet egress.
- Alert the IR team and switch on EDR detections for Win32k exploitation (see Detection section); CISA has flagged this CVE as actively used in ransomware campaigns.
Runbook step 2
Mitigation layers
- Network: micro-segment legacy Windows hosts with a deny-all default; only approved admin workstations may initiate RDP/SMB/WinRM. This breaks the lateral-movement step, since Win32k EoP is almost always the second stage after an initial phishing payload.
- Endpoint hardening: enforce Application Control (AppLocker, WDAC) with an allowlist policy to block unsigned loaders that stage the Win32k payload. Enable LSA Protection (RunAsPPL) and Credential Guard where the legacy OS supports it.
- IAM: enforce strict least privilege — no Domain Admin logon on workstations or legacy servers; implement Microsoft's Tier 0/1/2 admin separation.
- EDR/AV: refresh signatures and behavioural rules for known Win32k exploit families (DoublePulsar derivatives, Magniber loader chains, GandCrab payloads). Set Windows Defender Exploit Protection — or EDR equivalent — to force SEHOP, DEP and ASLR on.
- Backup and recovery: verify offline backups of the legacy estate and document restore times; the ransomware pairing of this CVE makes data-loss scenarios realistic.
- Medium term: formalise a migration/decommissioning plan for Windows 7 and Server 2008/R2. Under NIS2, running unsupported OS on essential services is documentable as a breach of Article 21 risk-management duties.
Runbook step 3
Detection rules
- Sysmon EID 1 (Process Create) where ParentImage is a browser/Office/mail client (
winword.exe,outlook.exe,chrome.exe) and the child runs from an unusual path (%TEMP%,%APPDATA%), followed by token manipulation — Sigma shape:selection.ParentImage|endswith: ['\winword.exe','\excel.exe']+child.Image|contains: ['\Temp\','\AppData\Local\Temp\']. - Sysmon EID 10 (ProcessAccess) targeting
lsass.exewith GrantedAccess 0x1010 or 0x1410 from a user-mode process that was spawned moments earlier — classic post-EoP pattern. - Windows Security EID 4672 (Special Privileges Assigned) for a user account not in a privileged group, correlated with EID 4688 (process start) from the same account inside a 60-second window.
- EDR telemetry: unexpected EPROCESS token swap — a process that started as a standard user suddenly performs operations under SYSTEM. KQL (Defender):
DeviceProcessEvents | where InitiatingProcessAccountName != "SYSTEM" and AccountName == "SYSTEM" and InitiatingProcessParentFileName in~ ("winword.exe","excel.exe","outlook.exe"). - Network/Zeek: local EoP is typically followed by SMB enumeration and WMI lateral movement; watch for anomalous SMB2 tree connects and WMI remote process launches (DCOM to port 135 plus dynamic RPC) originating from legacy hosts.
- Sysmon EID 1 (Process Create) where ParentImage is a browser/Office/mail client (
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 Server 2008, Windows 7, Windows Server 2008 R2. This CVE ID is unique from CVE-2018-8124, CVE-2018-8164, CVE-2018-8166.
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 versions | Fixed in | ||
|---|---|---|---|
| Microsoft | Windows 7 |
|
|
| Microsoft | Windows Server 2008 |
|
|
| Microsoft | Windows Server 2008 R2 |
|
|
Vendors and products
Affected operating systems
| Windows | microsoft | windows_7 | — |
| Windows | microsoft | windows_server_2008 | r2 |
| Windows | microsoft | windows_server_2008 | — |
Weakness classes (CWE)
CWE-404Improper Resource Shutdown or Release
Class
The product does not release or incorrectly releases a resource before it is made available for re-use.
Entry at MITRE CWE-404
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 45653 (opens in a new tab)exploit-db.com | PoC (publicly reported)reported, not verified | — |
References & sources
- exploit-db.com45653Exploit, x_refsource_EXPLOIT-DB
- securitytracker.com1040849Vulnerability database, x_refsource_SECTRACK
- securityfocus.com104034Vulnerability database, x_refsource_BID
- portal.msrc.microsoft.comen-US/security-guidance/advisory/CVE-2018-8120x_refsource_CONFIRM
- cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2018-8120government-resource
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<a href="https://intel.neosec.eu/en/cve/CVE-2018-8120"><img src="https://intel.neosec.eu/badge/cve/CVE-2018-8120.svg?lang=en" alt="CVE-2018-8120 – NEOSEC Intel" height="20"></a>