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CVE-2013-3900
Authenticode Signature Verification Flaw in Microsoft WinVerifyTrust (RCE)
CISA: Microsoft WinVerifyTrust function Remote Code Execution
- CVSS 3.1
- 5.5 medium
- EPSS
- 45%p99
- Published
- ·
- Added to KEV
AI analysisSummaries by Vani AI
Microsoft's WinVerifyTrust function improperly validates Windows Authenticode signatures on portable executable (PE) files, allowing crafted modifications to a signed binary — such as altered sections or checksum-table manipulation — to still pass signature verification. An attacker who tampers with a legitimately signed executable can distribute modified files that Windows and dependent security controls treat as authentic, gaining the trust of a valid digital signature and, ultimately, remote code execution in contexts that rely on signature checks. Any Microsoft Windows platform performing Authenticode verification through WinVerifyTrust is affected; the source data does not list specific Windows version ranges, but because WinVerifyTrust is core Windows functionality the exposure is very broad. The flaw was added to CISA's Known Exploited Vulnerabilities catalog on 2022-01-10, indicating confirmed in-the-wild exploitation, and EPSS puts its 30-day exploitation probability at about 44.6% (99th percentile), though no public PoC is known.
What to do: Apply Microsoft's updates for CVE-2013-3900 across all Windows systems per vendor instructions, as required for CISA KEV entries. Where supported, enable Microsoft's stricter certificate padding check (EnableCertPaddingCheck) per Microsoft guidance to harden signature verification against this bypass. Prioritize patching endpoints and servers that execute or validate downloaded, emailed, or otherwise externally sourced signed binaries, given confirmed exploitation and high EPSS.
| Product | Affected |
|---|---|
| Microsoft WinVerifyTrust function (Windows Authenticode signature verification for PE files) | — |
Estimated exposure
masshundreds of millions of Windows devices (near-universal across the Windows installed base) — WinVerifyTrust is part of the Authenticode infrastructure built into essentially all Windows desktops and servers, so exposure scales with the global Windows installed base rather than with a discrete product count.
Order-of-magnitude estimate by the model from install counts, market share and public scan data it knows; verify before quoting.
Description · NVD
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
KEVCISA Known Exploited Vulnerability
- Affected
- Microsoft WinVerifyTrust function
- Required action
- Apply updates per vendor instructions.
- Due date
- Ransomware use
- Unknown
- Vendors
- microsoft
- Products
- windows 10 1507, windows 10 1607, windows 10 1809, windows 10 1909, windows 10 20h2, windows 10 21h1, windows 10 21h2, windows 10 22h2, windows 11 21h2, windows 11 22h2, windows 11 23h2, windows 11 24h2
- Weakness
- CWE-347
- Vector
- CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
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