CVE-2013-3900 in Windows
Summary
by MITRE
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
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Analysis
by VulDB Data Team • 04/22/2026
The WinVerifyTrust signature validation vulnerability represents a critical flaw in Microsoft's code signing verification mechanism that has persisted across multiple Windows operating system versions from 2003 through 2013. This vulnerability resides within the core Windows cryptographic verification functions that are responsible for validating the authenticity and integrity of digitally signed executables and dynamic link libraries. The flaw specifically affects the WinVerifyTrust API function which is widely used by Windows applications and system components to verify the digital signatures of files before execution. When a PE (Portable Executable) file is presented for verification, the system should validate the file's cryptographic digest against the signature embedded within the file's digital certificate. However, the vulnerability allows attackers to bypass this crucial validation step by manipulating the PE file structure in a way that causes the verification process to skip critical digest checks.
The technical implementation of this vulnerability stems from improper handling of PE file structures during signature validation. The flaw occurs when the WinVerifyTrust function encounters PE files with malformed or specially crafted digest information within the file's certificate section. This allows attackers to create malicious PE files that appear to have valid signatures while actually containing executable code that can bypass security controls. The vulnerability is particularly dangerous because it affects the fundamental security mechanism that protects against unsigned or tampered executables, essentially undermining the entire code signing infrastructure that Windows relies upon for application authenticity verification. This weakness enables attackers to exploit the trust model that operating systems establish when executing signed binaries, creating a pathway for privilege escalation and arbitrary code execution without requiring elevated privileges.
The operational impact of this vulnerability extends far beyond simple code execution, as it fundamentally compromises the security posture of affected systems. Attackers can leverage this flaw to execute malicious code with the privileges of the user who runs the compromised application, potentially leading to complete system compromise. The vulnerability affects a broad range of Windows platforms including legacy systems like Windows XP and Server 2003, as well as more recent versions such as Windows 8 and Windows Server 2012, making it a widespread concern across enterprise environments. Organizations that rely on code signing to protect against malicious software can have their security policies circumvented, as attackers can create signed malicious binaries that bypass traditional security controls. This vulnerability particularly impacts enterprise environments where code signing is used as a security control, potentially allowing attackers to execute malicious software that would normally be blocked by security policies that require valid signatures.
Microsoft addressed this vulnerability through security updates that corrected the PE file digest validation logic within the WinVerifyTrust function, ensuring that all digest information is properly verified before accepting a file as authentic. The fix required modifications to how the system processes PE file structures during signature validation, specifically ensuring that cryptographic digests are validated against the actual file content rather than allowing malformed structures to bypass verification. Organizations should prioritize applying these security updates immediately to protect against exploitation attempts, as the vulnerability has been actively exploited in the wild. Security practitioners should also implement additional monitoring for suspicious file execution patterns and consider deploying application whitelisting solutions as additional defense layers. The vulnerability aligns with CWE-220 which addresses improper handling of cryptographic operations and relates to ATT&CK technique T1553.002 which covers software signing manipulation. Given the long support lifecycle of affected operating systems, organizations should also consider implementing network-based protections and endpoint detection solutions to identify and block exploitation attempts targeting this vulnerability.