CVE-2013-3900: Microsoft WinVerifyTrust function Remote Code Execution

CVE-2013-3900 is a remote code execution vulnerability in Microsoft’s WinVerifyTrust function, which performs Windows Authenticode signature verification for PE files. Because signature checks are a common trust boundary on Windows systems, a flaw here can let an attacker run code in the context of a process that validates a maliciously crafted file. IT and security teams should treat it as a high-priority Windows component issue and confirm exact impact and fixes against the vendor advisory.

CISA summarizes the issue as improper handling of Authenticode signature verification for PE files. The associated weakness is CWE-20 (Improper Input Validation). Ransomware use is not documented for this CVE. The required action is to apply updates per vendor instructions.

How it works

WinVerifyTrust is used by Windows and many applications to decide whether a PE file’s Authenticode signature is valid and trustworthy. CWE-20 means the function does not adequately validate certain inputs during that verification process. An attacker who can present a specially crafted PE file to a component that calls WinVerifyTrust may cause the verification logic to behave incorrectly, leading to remote code execution in the verifying process.

Exact exploit mechanics, file formats, or call paths are not detailed in the provided facts. Defenders should assume that any workflow that automatically or interactively verifies PE signatures—installers, update clients, security tools, or user-driven “run this file” paths—could be in scope until the vendor advisory is reviewed. Do not invent or rely on unconfirmed exploit details; treat the class as improper validation during Authenticode checks on PE files.

Am I affected? How to find it in your systems

The vulnerability affects the Microsoft WinVerifyTrust function on Windows systems that perform Authenticode verification of PE files. That capability is widespread: it appears on endpoints, servers, and any environment where signed binaries are checked before execution or installation.

Practical inventory steps:

• Identify Windows hosts (workstations, servers, jump boxes, build systems) that load or verify PE files, including software distribution and security scanning pipelines.
• Confirm whether applications or OS components on those hosts call WinVerifyTrust or equivalent Authenticode APIs when handling untrusted or user-supplied binaries.
• Check installed updates and security baselines against the Microsoft advisory for CVE-2013-3900 to determine which builds are patched; do not assume version ranges without vendor confirmation.
• Review configuration that enables or forces signature verification for downloaded or removable-media PE files.

Telemetry and log signs of exploitation are not specified in the facts. In general for this class, watch for unexpected crashes or anomalies in processes that verify signatures, unusual PE files introduced into trust paths, and execution of binaries shortly after failed or anomalous verification events. Correlate with EDR/AV alerts on suspicious PE handling. Confirm any IOCs or detection guidance in the vendor advisory and your own threat intel.

How to remediate

Patch first. Apply the Microsoft updates that address CVE-2013-3900 exactly as directed in the vendor advisory. CISA’s required action is to apply updates per vendor instructions. Validate deployment across all Windows images, including offline and golden images, VDI templates, and long-lived servers.

After patching:

• Re-verify that Authenticode-related components are at the fixed level on a sample of systems.
• Harden PE trust paths: prefer execution only from trusted locations, enforce application allowlisting where feasible, and limit which accounts and services can introduce or verify untrusted PE files.
• Ensure security tools that themselves verify signatures are updated and configured to fail closed on verification errors where operationally acceptable.
• Document residual risk for any systems that cannot yet be patched and track them under change control.

If you can't patch immediately

Use compensating controls until the vendor update can be applied:

• Segment high-risk Windows hosts and restrict inbound paths that deliver PE files (email gateways, web downloads, file shares, removable media).
• Where available, use virtual patching or WAF/IPS rules that target known exploitation patterns for this issue—only after confirming rule coverage against the vendor advisory and your traffic profile.
• Disable or constrain automatic signature verification and auto-execution of untrusted PE files if the business can tolerate the operational impact; prefer manual, isolated verification in a sandbox.
• Tighten application control policies so only known-good signed binaries run, and alert on verification failures or execution from user-writable paths.
• Increase monitoring on processes that call WinVerifyTrust-equivalent APIs: log verification outcomes, parent/child process chains, and network activity following PE introduction.

These measures reduce exposure but do not replace the official update. Schedule patching as soon as possible.

If your data may have been exposed

Actively exploited remote code execution flaws can lead to full host compromise and follow-on data access or ransomware, though ransomware use is not documented for this CVE. If you suspect exploitation, isolate affected systems, preserve forensic evidence, rotate credentials that may have been present on the host, and follow your incident response plan. As a routine check, you can run a free exposure scan of your email addresses against known breach datasets to see whether associated accounts appear in prior public breaches and then prioritize password resets and MFA.