CWE-66: Improper Handling of File Names that Identify Virtual Resources

BaseDraft

The product does not handle or incorrectly handles a file name that identifies a "virtual" resource that is not directly specified within the directory that is associated with the file name, causing the product to perform file-based operations on a resource that is not a file.

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Extended Description

Virtual file names are represented like normal file names, but they are effectively aliases for other resources that do not behave like normal files. Depending on their functionality, they could be alternate entities. They are not necessarily listed in directories.

Technical Details

Structure
Simple
Vulnerability Mapping
ALLOWED

Applicable To

Languages
Not Language-Specific
Platforms

Source-backed guidance

Additional facts reviewed against primary or authoritative security sources.

Detect Improper Handling of File Names that Identify Virtual Resources with Automated Static Analysis - Binary or Bytecode

Documented detection approaches include Automated Static Analysis - Binary or Bytecode, Manual Static Analysis - Binary or Bytecode, Dynamic Analysis with Automated Results Interpretation, and Dynamic Analysis with Manual Results Interpretation; recorded impacts include Other; observed examples include CVE-1999-0278, CVE-2004-1084, and CVE-2002-0106. Use these source-defined anchors to turn CWE-66 into implementation, review, and verification checks for the affected component.

CWE-66: Improper Handling of File Names that Identify Virtual Resources — MITRE CWE

Prevent CWE-66 through an SSDF control plan

Use NIST SSDF practices to make prevention of CWE-66, Improper Handling of File Names that Identify Virtual Resources, an explicit development outcome. Translate the CWE definition into security requirements and design constraints, choose safer implementation patterns and toolchain checks, and define acceptance evidence before release. Feed every confirmed occurrence back into the requirements, design review, and coding rules so the same root cause is removed across the product rather than patched in one location.

NIST SP 800-218 Secure Software Development Framework — National Institute of Standards and Technology

Triage CWE-66 against known exploitation evidence

Use CISA's Known Exploited Vulnerabilities catalog to test whether a vulnerability mapped to CWE-66, Improper Handling of File Names that Identify Virtual Resources, has evidence of exploitation in the wild. Confirm the CVE-to-CWE root-cause mapping independently before attaching the example, then capture the affected product, required action, and remediation deadline. A missing KEV match is not evidence that the weakness is unexploited, and a KEV entry must not be generalized to every occurrence of this CWE.

Known Exploited Vulnerabilities Catalog — Cybersecurity and Infrastructure Security Agency

Apply precise root-cause mapping to CWE-66

Apply MITRE's full root-cause mapping guidance when using CWE-66, Improper Handling of File Names that Identify Virtual Resources. Separate weakness language from attacker prerequisites and technical impact, check the entry's abstraction and vulnerability-mapping notes, and prefer the most specific Base or Variant supported by the evidence. Record the rejected alternatives and require an independent review before the mapping is used for remediation trends or program metrics.

CVE to CWE Root Cause Mapping Guidance — MITRE CWE

Validate CWE-66 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-66, Improper Handling of File Names that Identify Virtual Resources. Confirm the finding describes the causal weakness rather than an impact or attack pattern, compare the abstraction and mapping notes with plausible alternatives, and have a second reviewer challenge the selection. Preserve the evidence and reasoning so recurring defects can be measured against one consistent identifier.

CVE to CWE Root Cause Mapping Quick Tips — MITRE CWE

Frequently Asked Questions

What is CWE-66: Improper Handling of File Names that Identify Virtual Resources?+

CWE-66: Improper Handling of File Names that Identify Virtual Resources is a Common Weakness Enumeration (CWE) entry maintained by MITRE. The product does not handle or incorrectly handles a file name that identifies a "virtual" resource that is not directly specified within the directory that is associated with the file name, causing the product to perform file-based operations on a resource that is not a file. Virtual file names are represented like normal file names, but they are effectively aliases for other resources that do not behave like normal files. Depending on their functionality, they could be alternate entities. They are not necessarily listed in directories.

What are the security consequences of Improper Handling of File Names that Identify Virtual Resources?+

If exploited, CWE-66 (Improper Handling of File Names that Identify Virtual Resources) it can compromise Other, leading to outcomes such as Other.

How is Improper Handling of File Names that Identify Virtual Resources detected?+

CWE-66 can be detected using Automated Static Analysis - Binary or Bytecode, Manual Static Analysis - Binary or Bytecode, Dynamic Analysis with Automated Results Interpretation, Dynamic Analysis with Manual Results Interpretation, Manual Static Analysis - Source Code and Automated Static Analysis - Source Code. Combining automated tooling with manual review typically yields the best coverage.

Which programming languages are affected by Improper Handling of File Names that Identify Virtual Resources?+

CWE-66 commonly affects Not Language-Specific. Note that weaknesses are often language-agnostic patterns, so secure coding practices apply broadly.

What are real-world examples of Improper Handling of File Names that Identify Virtual Resources?+

MITRE documents real CVEs mapped to CWE-66, including CVE-1999-0278, CVE-2004-1084 and CVE-2002-0106. You can look up the full details of each CVE, including CVSS scores and remediation guidance, on our CVE Lookup tool.

What is the difference between a CWE and a CVE?+

A CWE (Common Weakness Enumeration) like CWE-66 describes a category of software weakness — the underlying flaw type. A CVE (Common Vulnerabilities and Exposures) identifies a specific, real-world vulnerability in a particular product. In short, a CWE is the kind of mistake, and a CVE is an instance of that mistake being found in software.

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