WinVerifyTrust Signature Validation Vulnerability (CVE-2013-3900)
Published Last modified In CISA KEV since Sources: CVE.org
What is affected, what to do
Why is Microsoft republishing a CVE from 2013? We are republishing CVE-2013-3900 in the Security Update Guide to update the Security Updates table and to inform customers that the EnableCertPaddingCheck is available in all currently supported versions of Windows 10 and Windows 11. While the format is different from the original CVE published in 2013, except for clarifications about how to configure the EnableCertPaddingCheck registry value, the information herein remains unchanged from the original text published on December 10, 2013, Microsoft does not plan to enforce the stricter verification behavior as a default functionality on supported releases of Microsoft Windows. This behavior remains available as an opt-in feature via reg key setting, and is available on supported editions of Windows released since December 10, 2013. This includes all currently supported versions of Windows 10 and Windows 11. The supporting code for this reg key was incorporated at the time of release for Windows 10 and Windows 11, so no security update is required; however, the reg key must be set.
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
5.5
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: NVD, CVSS v3
5.5
CVSS v3
Severity Medium on the scale from 0 to 10.
Source: CVE.org
44.7 %
EPSS score
Elevated — model estimates 10-50% exploitation likelihood.
Source: FIRST EPSS, percentile 98.8
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- 205.54 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- 5.5 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- 5.5
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- 44.7 %
- 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- 98.8
- 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: partial
- 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-347
Response and mitigation
Why act now?
Prioritisation rationale
This flaw is on KEV because attackers take legitimately signed binaries, often Microsoft's own, and append malicious code that still passes Authenticode validation. That defeats the signature-based trust decisions made by users, AV and application control. It typically appears in phishing and malware loader chains aimed at broad user populations. On paper it is local, requires user interaction and carries only medium base severity, but its exploitation likelihood is very high. Because the fix is disabled by default and no regular patch cycle closes it, practically every unhardened Windows fleet is exposed. Given that remediation is a single registry setting, rate it high regardless of the base score and close it fleet-wide in the short term. CISA does not flag known ransomware use.
Runbook step 1
Immediate response (0-24 h)
- No patch to deploy, but you must set a registry value. Microsoft ships the stricter Authenticode verification as opt-in only. Enable
EnableCertPaddingCheckon every Windows client and server:reg add "HKLM\Software\Microsoft\Cryptography\Wintrust\Config" /v EnableCertPaddingCheck /t REG_SZ /d 1 /fOn 64-bit systems, also run:reg add "HKLM\Software\Wow6432Node\Microsoft\Cryptography\Wintrust\Config" /v EnableCertPaddingCheck /t REG_SZ /d 1 /fThe setting takes effect after a reboot. Microsoft documents the value as the string "1". - Deploy fleet-wide via GPO (Group Policy Preferences → Registry), Intune (remediation script or custom configuration) or SCCM. Pick a pilot ring today and target full coverage within 24-72 h.
- Baseline your exposure: Any Windows host without the key is vulnerable, which in most fleets means nearly all of them. Query via Defender Vulnerability Management, Qualys/Tenable checks, or a remoted
Get-ItemPropertyscript. Keep the result as evidence for NIS2 risk-management documentation. - Test compatibility: Some legitimate installers append configuration data inside the signature structure and will show as unsigned once the check is on. Validate software-distribution packages (MSI/EXE installers, third-party updaters) in the pilot ring.
- Harden high-risk hosts first: admin workstations, jump hosts, build servers, users with local admin rights, and endpoints with heavy email or download exposure.
- No patch to deploy, but you must set a registry value. Microsoft ships the stricter Authenticode verification as opt-in only. Enable
Runbook step 2
Mitigation layers
- Endpoint hardening / application control: For sensitive systems, use WDAC or AppLocker hash rules rather than publisher-only rules. Publisher rules trust exactly the signature this flaw lets attackers abuse. Also enable the Microsoft recommended block rules.
- Least privilege: Remove standing local admin rights (Windows LAPS, just-in-time admin). Impact scales with the privileges of the user who runs the file.
- Email and web gateway: Block or detonate executable attachments (
.exe,.dll,.msi,.scr) and archives containing PEs. Do not exempt validly signed files from sandbox analysis. - Defender ASR rules: Set "Block executable files from running unless they meet a prevalence, age, or trusted list criterion" and "Block executable content from email client and webmail" to block mode.
- Configuration drift control: Add
Wintrust\Config\EnableCertPaddingCheckto your hardening baseline and alert on deviations through Intune compliance or SCCM configuration baselines.
Runbook step 3
Detection rules
- Tampering with the mitigation (Sysmon EID 12/13/14, MDE): If the value is deleted or changed, treat it as a possible deliberate rollback. KQL:
DeviceRegistryEvents | where RegistryKey has @"Cryptography\Wintrust\Config" and RegistryValueName == "EnableCertPaddingCheck" and (ActionType == "RegistryValueDeleted" or RegistryValueData != "1") - Signed binary with an unexpected hash (Sysmon EID 1 / EID 7): Look for processes or DLLs signed by Microsoft or another trusted vendor whose SHA256 does not match known-good builds or is unknown to VirusTotal/NSRL. Sigma shape:
Signed: true AND Signature contains 'Microsoft' AND Image|contains '\AppData\' OR '\Temp\' OR '\Downloads\' - Oversized certificate table / data appended in the security directory (YARA, file scanning): Look for content after the PKCS#7 blob, such as script or shellcode fragments. Rule idea:
pe.number_of_signatures > 0plus strings like<script,powershell,mshtaor long Base64 runs within the signature region. - Suspicious process ancestry (EDR): Watch for signed Microsoft utilities, e.g. installer components, that launch from user-writable paths and then spawn
mshta.exe,rundll32.exe,regsvr32.exeorpowershell.exe. SPL:index=sysmon EventCode=1 ParentImage IN ("*\\AppData\\*","*\\Temp\\*") Image IN ("*\\mshta.exe","*\\rundll32.exe","*\\powershell.exe") - Proactive hunt: Enumerate Microsoft-signed files outside
C:\WindowsandC:\Program Filesacross the fleet and compare their hashes against reference values.
- Tampering with the mitigation (Sysmon EID 12/13/14, MDE): If the value is deleted or changed, treat it as a possible deliberate rollback. KQL:
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
Why is Microsoft republishing a CVE from 2013? We are republishing CVE-2013-3900 in the Security Update Guide to update the Security Updates table and to inform customers that the EnableCertPaddingCheck is available in all currently supported versions of Windows 10 and Windows 11. While the format is different from the original CVE published in 2013, except for clarifications about how to configure the EnableCertPaddingCheck registry value, the information herein remains unchanged from the original text published on December 10, 2013, Microsoft does not plan to enforce the stricter verification behavior as a default functionality on supported releases of Microsoft Windows. This behavior remains available as an opt-in feature via reg key setting, and is available on supported editions of Windows released since December 10, 2013. This includes all currently supported versions of Windows 10 and Windows 11. The supporting code for this reg key was incorporated at the time of release for Windows 10 and Windows 11, so no security update is required; however, the reg key must be set. See the Security Updates table for the list of affected software. Vulnerability Description A remote code execution vulnerability exists in the way that the WinVerifyTrust function handles Windows Authenticode signature verification for portable executable (PE) files. An anonymous attacker could exploit the vulnerability by modifying an existing signed executable file to leverage unverified portions of the file in such a way as to add malicious code to the file without invalidating the signature. An attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. If a user is logged on with administrative user rights, an attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights. Exploitation of this vulnerability requires that a user or application run or install a specially crafted, signed PE file. An attacker could modify an... See more at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2013-3900
Source: cvelistv5, NVD (NIST), CISA KEV Catalog, CVE.org (MITRE)
Vendors and products
- Microsoft Windows 10 1507
- Microsoft Microsoft Windows 10 1607
- Microsoft Microsoft Windows 10 1809
- Microsoft Windows 10 1909
- Microsoft Windows 10 20h2
- Microsoft Windows 10 21h1
- Microsoft Microsoft Windows 10 21H2
- Microsoft Microsoft Windows 10 22h2
- Microsoft Windows 11 21h2
- Microsoft Microsoft Windows 11 22H2
- Microsoft Microsoft Windows 11 23H2
- Microsoft Microsoft Windows 11 24H2
Affected operating systems
| Windows | microsoft | windows_10_1507 | — |
| Windows | microsoft | windows_10_1607 | — |
| Windows | microsoft | windows_10_1809 | — |
| Windows | microsoft | windows_10_1909 | — |
| Windows | microsoft | windows_10_20h2 | — |
| Windows | microsoft | windows_10_21h1 | — |
| Windows | microsoft | windows_10_21h2 | — |
| Windows | microsoft | windows_10_22h2 | — |
| Windows | microsoft | windows_11_21h2 | — |
| Windows | microsoft | windows_11_22h2 | — |
| Windows | microsoft | windows_11_23h2 | — |
| Windows | microsoft | windows_11_24h2 | — |
| 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_server_2016 | — |
| Windows | microsoft | windows_server_2019 | — |
| Windows | microsoft | windows_server_2022 | — |
| Windows | microsoft | windows_server_2022_23h2 | — |
| Windows | microsoft | windows_server_2025 | — |
Weakness classes (CWE)
CWE-347Improper Verification of Cryptographic Signature
Base
The product does not verify, or incorrectly verifies, the cryptographic signature for data.
Entry at MITRE CWE-347
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 | |
| PoC-in-GitHub (nomi-sec) | nessus-vulnerability-scanning-lab (opens in a new tab)github.com | PoC (publicly reported)reported, not verified |
References & sources
- Microsoft Security Update GuideWinVerifyTrust Signature Validation VulnerabilityVendor advisory
- docs.microsoft.comMS13-098Vendor advisory, x_refsource_MS, x_transferred
- blogs.technet.comb/srd/archive/2013/12/10/ms13-098-update-to-enhance-the-securit…x_refsource_CONFIRM, x_transferred
- cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2013-3900government-resource
Changes to this CVE
Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).
NVD analysis modifiedNVD
Record modifiedMicrosoft
Show 3 original changes
Individual changes of this event as published by NVD Type Action Before After Reference added —https://msrc.microsoft.com/update-guide/vulnerability/CVE-2013-3900Reference removed https://msrc.microsoft.com/update-guide/vulnerability/CVE-2013-3900—Reference type removed https://msrc.microsoft.com/update-guide/vulnerability/CVE-2013-3900 Types: Patch, Vendor Advisory—Source identifier: secure@microsoft.com
Record modifiedCISA ADP
CVSS V3.1: before AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H, after —
Show 5 original changes
Individual changes of this event as published by NVD Type Action Before After CVSS removed AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H—Weakness type (CWE) removed CWE-347—Reference added —https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2013-3900Reference removed https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2013-3900—Reference type removed https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2013-3900 Types: US Government Resource—Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0
Record modifiedCVE Program
Show 9 original changes
Individual changes of this event as published by NVD Type Action Before After Reference added —http://blogs.technet.com/b/srd/archive/2013/12/10/ms13-098-update-to-enhance-the-security-of-authenticode.aspxReference added —https://docs.microsoft.com/en-us/security-updates/securitybulletins/2013/ms13-098Reference added —https://msrc.microsoft.com/update-guide/vulnerability/CVE-2013-3900Reference removed http://blogs.technet.com/b/srd/archive/2013/12/10/ms13-098-update-to-enhance-the-security-of-authenticode.aspx—Reference removed https://docs.microsoft.com/en-us/security-updates/securitybulletins/2013/ms13-098—Reference removed https://msrc.microsoft.com/update-guide/vulnerability/CVE-2013-3900—Reference type removed http://blogs.technet.com/b/srd/archive/2013/12/10/ms13-098-update-to-enhance-the-security-of-authenticode.aspx Types: Broken Link—Reference type removed https://docs.microsoft.com/en-us/security-updates/securitybulletins/2013/ms13-098 Types: Vendor Advisory—Reference type removed https://msrc.microsoft.com/update-guide/vulnerability/CVE-2013-3900 Types: Patch, Vendor Advisory—Source identifier: af854a3a-2127-422b-91ae-364da2661108
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<a href="https://intel.neosec.eu/en/cve/CVE-2013-3900"><img src="https://intel.neosec.eu/badge/cve/CVE-2013-3900.svg?lang=en" alt="CVE-2013-3900 – NEOSEC Intel" height="20"></a>