Microsoft Win32k Privilege Escalation Vulnerability (CVE-2013-3660)
Published In CISA KEV since Sources: CVE.org
What is affected, what to do
The EPATHOBJ::pprFlattenRec function in win32k.sys in the kernel-mode drivers in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8, and Windows Server 2012 does not properly initialize a pointer for the next object in a certain list, which allows local users to obtain write access to the PATHRECORD chain, and consequently gain privileges, by triggering excessive consumption of paged memory and then making many FlattenPath function calls, aka "Win32k Read AV 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 2008
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
39.3 %
EPSS score
Elevated — model estimates 10-50% exploitation likelihood.
Source: FIRST EPSS, percentile 98.6
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- 216.78 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- 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- 39.3 %
- 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- 98.6
- 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 7 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-119
Response and mitigation
Why act now?
Prioritisation rationale
This is a reliable, long-public local privilege escalation to SYSTEM. Attackers use it as a second stage after phishing, browser exploits or stolen user accounts, then harvest credentials and move laterally. It requires local access, but exploitation likelihood is very high, and CISA does not flag known ransomware use. In a modern, patched estate the risk is low. If you still run unsupported Windows in OT, medical, lab or terminal-server roles, rank it high, especially where those hosts are multi-user or see privileged domain logons.
Runbook step 1
Immediate response (0-24 h)
- Inventory legacy hosts: Use your CMDB, AD (
Get-ADComputer -Filter * -Properties OperatingSystem) or EDR inventory to find every Windows XP, Vista, 7, 8, RT, Server 2003, 2008/2008 R2 and 2012 machine. All of these are past end of support. Treat any unpatched host as fully compromisable once an attacker gets user-level code execution. - Verify and deploy the security update: A patch is available from the vendor — look up the KB number in the Microsoft advisory for CVE-2013-3660. Confirm installation via WSUS/SCCM compliance reports or
wmic qfe listrather than assuming it from patch dates. - Isolate hosts that cannot be patched: Move embedded, OT-adjacent (HMI, control-room PCs) or vendor-locked servers into a dedicated segment. Restrict interactive logon to named personnel.
- Hunt for compromise on exposed legacy systems: Prioritise terminal servers, shared jump hosts and kiosks. Look for unexpected SYSTEM processes, new local admin accounts and newly installed services (see Detection rules).
- Rotate credentials on suspicion: If you confirm local privilege escalation, treat every credential cached on the host as burned. That includes local admin, service accounts and cached domain logons. Reset LAPS passwords and affected service-account secrets immediately.
- Inventory legacy hosts: Use your CMDB, AD (
Runbook step 2
Mitigation layers
- Application control (endpoint hardening): Use AppLocker or Software Restriction Policies on legacy hosts to block execution from user-writable paths such as
%USERPROFILE%,%TEMP%,%APPDATA%and Downloads. The exploit needs locally executed code, so allow-listing breaks the chain before the kernel is touched. - Network segmentation: Put legacy systems in their own VLAN and block outbound internet except for explicitly required destinations. Restrict SMB (445/tcp), RDP (3389/tcp) and WinRM (5985/5986/tcp) from that segment towards core networks and domain controllers. This limits lateral movement after a successful escalation.
- IAM / least privilege: Use GPO to limit "Allow log on locally" and "Allow log on through Remote Desktop Services" on legacy hosts to a minimal group. Keep Tier 0/1 privileged accounts off these hosts via "Deny log on" policies, so a SYSTEM takeover yields no domain-admin credentials.
- Shrink the initial-access surface: Allow no mail clients, no general web browsing and no Office macros on affected hosts. Exploitation requires user interaction or local code execution and is typically chained with phishing or browser exploits.
- Retirement plan: For systems with no patch or support path, record a dated replacement plan in the risk register. Until replacement, treat the compensating controls above as mandatory. This documentation matters for NIS2/KRITIS audits.
- Application control (endpoint hardening): Use AppLocker or Software Restriction Policies on legacy hosts to block execution from user-writable paths such as
Runbook step 3
Detection rules
- Privilege jump in the process tree (Sysmon EID 1 / Security 4688): Alert on a process running as
NT AUTHORITY\SYSTEMor with System integrity whose parent runs as a standard user from a user-writable path. Sigma shape:ParentImage|contains: '\Users\'ANDUser|contains: 'SYSTEM'ANDImage|endswith: ['\cmd.exe','\powershell.exe']. - Failed exploitation attempts (System log): The technique exhausts paged pool and hammers
FlattenPath, so failed attempts often bluescreen the host. Watch for Event ID 1001 (BugCheck) and Event ID 41 (Kernel-Power) withwin32k.sysin the dump, and for clusters of unexpected reboots on multi-user hosts. - Memory-pressure anomaly (Perfmon/EDR telemetry): Flag a single unprivileged process driving paged-pool usage to its limit, which may surface as Event ID 2019/2020 (paged pool depleted). Correlate with the logged-on user in the SIEM.
- Post-escalation activity (Security 4720/4732, System 7045): Alert on a new local account, an addition to local Administrators, or a new service shortly after an interactive logon. KQL sketch:
SecurityEvent | where EventID in (4720,4732,7045) | join kind=inner (SecurityEvent | where EventID==4624 and LogonType in (2,10)) on Computer. - Known exploit artefacts (EDR/AV): Public exploit code exists, including a Metasploit module. Escalate AV/EDR hits for Win32k EPATHOBJ exploits or Meterpreter payloads on legacy hosts rather than just quarantining them.
- Privilege jump in the process tree (Sysmon EID 1 / Security 4688): Alert on a process running as
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 EPATHOBJ::pprFlattenRec function in win32k.sys in the kernel-mode drivers in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP2, Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8, and Windows Server 2012 does not properly initialize a pointer for the next object in a certain list, which allows local users to obtain write access to the PATHRECORD chain, and consequently gain privileges, by triggering excessive consumption of paged memory and then making many FlattenPath function calls, aka "Win32k Read AV 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 RT Gold
- Microsoft Microsoft Windows Server 2003
- Microsoft Microsoft Windows Server 2008
- Microsoft Microsoft Windows Server 2012
- Microsoft Microsoft Windows Vista Gold on X64
- Microsoft Microsoft Windows XP Service Pack 1 Home Edition
Affected operating systems
| Windows | microsoft | windows_7 | — |
| Windows | microsoft | windows_8 | — |
| Windows | microsoft | windows_rt | — |
| Windows | microsoft | windows_server_2003 | — |
| Windows | microsoft | windows_server_2008 | r2 |
| Windows | microsoft | windows_server_2008 | — |
| Windows | microsoft | windows_server_2012 | — |
| Windows | microsoft | windows_vista | — |
| Windows | microsoft | windows_xp | — |
Weakness classes (CWE)
CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer
Class
The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.
Entry at MITRE CWE-119
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 25611 (opens in a new tab)exploit-db.com | PoC (publicly reported)reported, not verified | — |
References & sources
- archives.neohapsis.com20130517 Re: exploitation ideas under memory pressureMailing list, x_refsource_FULLDISC, Broken link
- exploit-db.com25611Exploit, x_refsource_EXPLOIT-DB, Exploit, Third-party advisory, Vulnerability database
- archives.neohapsis.com20130517 exploitation ideas under memory pressureMailing list, x_refsource_FULLDISC, Broken link
- secunia.com53435Third-party advisory, x_refsource_SECUNIA, Broken link, Vendor advisory
- osvdb.org93539Vulnerability database, x_refsource_OSVDB, Broken link
- twitter.comtaviso/statuses/309157606247768064x_refsource_MISC, Exploit
- computerworld.coms/article/9239477x_refsource_MISC, Broken link
- theverge.com2013/5/23/4358400/google-engineer-bashes-microsoft-discloses-wi…x_refsource_MISC, Press coverage
- oval.cisecurity.orgoval:org.mitre.oval:def:17360Vulnerability database, signature, x_refsource_OVAL, Broken link
- reddit.comr/netsec/comments/1eqh66/0day_windows_kernel_epathobj_vulnerabi…x_refsource_MISC, Exploit, Issue tracking
- archives.neohapsis.com20130603 Re: exploitation ideas under memory pressureMailing list, x_refsource_FULLDISC, Broken link
- us-cert.govTA13-190AThird-party advisory, x_refsource_CERT, Third-party advisory, US government resource
- docs.microsoft.comMS13-053Vendor advisory, x_refsource_MS, Patch, Vendor advisory
- twitter.comtaviso/statuses/335557286657400832x_refsource_MISC, Not applicable
- cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2013-3660government-resource, US government resource
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<a href="https://intel.neosec.eu/en/cve/CVE-2013-3660"><img src="https://intel.neosec.eu/badge/cve/CVE-2013-3660.svg?lang=en" alt="CVE-2013-3660 – NEOSEC Intel" height="20"></a>