CriticalCVE-2004-0210

    Microsoft Windows Privilege Escalation Vulnerability (CVE-2004-0210)

    Published In CISA KEV since Sources: CVE.org

    What is affected, what to do

    The POSIX component of Microsoft Windows NT and Windows 2000 allows local users to execute arbitrary code via certain parameters, possibly by modifying message length values and causing a buffer overflow.

    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 eq 2.2..2.2
    • Microsoft Windows NT eq 4.0..4.0

    Not sure whether and how you are affected? Ask a question about this vulnerability

    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

    7.2 %

    EPSS score

    Moderate — model estimates 1-10% exploitation likelihood.

    Source: FIRST EPSS, percentile 94.3

    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
    210.14 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.

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    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“.

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    7.2 %
    Moderate — model estimates 1-10% 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
    94.3
    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-120

    Response and mitigation

    Why act now?

    Prioritisation rationale

    CISA added this flaw during a bulk back-fill of historically exploited vulnerabilities. It is locally exploitable with only a low-privileged account and no user interaction, and it yields full compromise of confidentiality, integrity and availability. Exploitation likelihood is unusually high for a vulnerability this old, though CISA has no record of ransomware use. Attackers typically use it as a second stage after gaining a session through weak passwords, RDP or removable media, mostly against long-lived OT, medical and specialist systems. If you run no NT/2000 estate, it's irrelevant. If you do, especially in production or utility networks, treat it as high priority, and prioritise isolating the host over applying the single patch.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Inventory first: Identify every host running Windows NT 4.0, Windows 2000 or Interix 2.2 using your CMDB, the AD operatingSystem attribute and passive network discovery. In critical-infrastructure environments, check control-room HMIs, SCADA engineering workstations, medical and lab devices, and legacy application servers.
      • Patch where still feasible: Microsoft shipped the fix as Security Bulletin MS04-020 (KB841872); verify the identifier in Microsoft's bulletin archive. Both operating systems are long past end of support, so this patch closes only this flaw, not the many that followed.
      • Disable the POSIX subsystem where you can't patch:
        • Under HKLM\SYSTEM\CurrentControlSet\Control\Session Manager\SubSystems, remove Posix from the Optional value.
        • Back up the Posix value, then delete it and reboot.
        • Before you do, confirm with the system owner that no application depends on POSIX or Interix.
      • Restrict interactive logons: Cut local and domain user accounts on legacy hosts to the bare minimum. Disable or rotate shared operator accounts, because exploitation requires an authenticated session.
      • Isolate the network: Move affected hosts into a dedicated segment. Block RDP/Terminal Services (TCP 3389), SMB (TCP 139/445) and NetBIOS (UDP 137/138) from the corporate LAN so attackers can't obtain a local session in the first place.

    2. Runbook step 2

      Mitigation layers

      • Network segmentation: Place legacy systems in their own zones and conduits per IEC 62443. Use allow-list-only flows with no internet egress. Administer them only via a hardened jump host with MFA.
      • IAM / least privilege: Limit SeInteractiveLogonRight to named accounts through local security policy. Disable the Guest account and revoke Terminal Services access where it isn't operationally required.
      • Endpoint hardening:
        • Disable removable media and autorun, which are a common way to drop exploit binaries locally.
        • Lock down ACLs on %SystemRoot%\system32\psxss.exe, posix.exe and psxdll.dll to SYSTEM/Administrators, or rename them after change approval.
      • Compensating network controls (IPS): Apply Suricata/Snort rules on the segment for lateral-movement patterns, such as SMBv1 sessions from unknown sources or RDP logons outside maintenance windows. The exploit itself is local, so you can't write a network signature for it.
      • Strategic: Put replacement or restricted virtualisation on the risk treatment plan (ISO 27001 A.8.8). Formalise residual-risk acceptance in line with NIS2 Art. 21.

    3. Runbook step 3

      Detection rules

      • POSIX subsystem process launch: Enable process tracking on Windows 2000/NT. Treat Security Event ID 592 (process created) for psxss.exe or posix.exe with an unusual parent or user as high severity. Example SIEM query: EventID=592 AND Image IN ("*\\psxss.exe","*\\posix.exe").
      • Post-logon privilege escalation: Correlate Event 528/540 (standard user logon) followed shortly by Event 592 spawning a SYSTEM-context process. Also flag Event 624/636 (account created or added to Administrators) in the same window.
      • Integrity monitoring: Use file and registry integrity monitoring (Tripwire or similar) on Session Manager\SubSystems, psxss.exe and psxdll.dll. Alert on unexpected changes or new binaries in user-profile and temp directories.
      • Network telemetry (Zeek/Suricata): Passively surface legacy hosts via the SMB dialect NT LM 0.12 (smb_mapping.log/smb1) and OS fingerprinting (p0f). Alert on RDP sessions to these hosts outside defined maintenance windows.

    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 POSIX component of Microsoft Windows NT and Windows 2000 allows local users to execute arbitrary code via certain parameters, possibly by modifying message length values and causing a buffer overflow.

    Source: CISA KEV Catalog, NVD (NIST), cvelistv5

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    microsoftinterix
    • 2.2
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Windowsmicrosoftwindows_2000—
    Windowsmicrosoftwindows_nt4.0

    Weakness classes (CWE)

    • CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

      Base

      The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.

      Entry at MITRE CWE-120

    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.

    Public exploit references
    CISA KEV CatalogCISA Known Exploited Vulnerability (opens in a new tab)cisa.govactively exploited

    References & sources

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