CWE-66 Base Brouillon

Improper Handling of File Names that Identify Virtual Resources

This vulnerability occurs when software incorrectly processes a filename that points to a 'virtual' resource—like a device, pipe, or internal system object—instead of a regular file. The application…

Définition

What is CWE-66?

This vulnerability occurs when software incorrectly processes a filename that points to a 'virtual' resource—like a device, pipe, or internal system object—instead of a regular file. The application mistakenly performs file operations (like read, write, or copy) on this non-file resource, which can lead to crashes, data exposure, or unexpected system behavior.
Virtual resources, such as `/dev/random` on Linux or `\\.\COM1` on Windows, use file-like naming conventions but represent system interfaces, devices, or in-memory objects. When an application treats these paths as ordinary files—for example, by blindly passing user-supplied input to file APIs—it can trigger actions the system never intended for file handling, like reading from a hardware port or writing to a system pipe. Developers can prevent this by validating and sanitizing all file path inputs, explicitly checking for and blocking known virtual resource patterns or namespace prefixes (like `\\.\` or `/proc/`). Using safe API functions that restrict operations to regular filesystem objects, rather than low-level system calls, also adds a critical layer of defense against this confusion.
Impact réel

Real-world CVEs caused by CWE-66

  • CVE-1999-0278

    In IIS, remote attackers can obtain source code for ASP files by appending "::$DATA" to the URL.

  • CVE-2004-1084

    Server allows remote attackers to read files and resource fork content via HTTP requests to certain special file names related to multiple data streams in HFS+.

  • CVE-2002-0106

    Server allows remote attackers to cause a denial of service via a series of requests to .JSP files that contain an MS-DOS device name.

Comment les attaquants l'exploitent

Parcours de l'attaquant étape par étape

  1. 1

    Identifier un chemin de code qui traite des entrées non fiables sans validation.

  2. 2

    Élaborer une charge utile qui exploite le comportement non sécurisé — injection, traversal, débordement ou abus de logique.

  3. 3

    Délivrer la charge utile via une requête normale et observer la réaction de l'application.

  4. 4

    Itérer jusqu'à ce que la réponse divulgue des données, exécute le code de l'attaquant ou élève les privilèges.

Exemple de code vulnérable

Vulnerable pseudo

MITRE n'a pas publié d'exemple de code pour ce CWE. Le motif ci-dessous est illustratif — voir Ressources pour les références canoniques.

Vulnérable pseudo 
// Example pattern — see MITRE for the canonical references.
function handleRequest(input) {
  // Untrusted input flows directly into the sensitive sink.
  return executeUnsafe(input);
}
Exemple de code sécurisé

Secure pseudo

Sécurisé pseudo 
// Validate, sanitize, or use a safe API before reaching the sink.
function handleRequest(input) {
  const safe = validateAndEscape(input);
  return executeWithGuards(safe);
}
What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.
Liste de contrôle de prévention

How to prevent CWE-66

  • Architecture Use safe-by-default frameworks and APIs that prevent the unsafe pattern from being expressible.
  • Implementation Validate input at trust boundaries; use allowlists, not denylists.
  • Implementation Apply the principle of least privilege to credentials, file paths, and runtime permissions.
  • Testing Cover this weakness in CI: SAST rules + targeted unit tests for the data flow.
  • Operation Monitor logs for the runtime signals listed in the next section.
Signaux de détection

How to detect CWE-66

Automated Static Analysis - Binary or Bytecode SOAR Partial

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Bytecode Weakness Analysis - including disassembler + source code weakness analysis

Manual Static Analysis - Binary or Bytecode SOAR Partial

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomalies

Dynamic Analysis with Automated Results Interpretation SOAR Partial

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Web Application Scanner Web Services Scanner Database Scanners

Dynamic Analysis with Manual Results Interpretation SOAR Partial

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Fuzz Tester Framework-based Fuzzer

Manual Static Analysis - Source Code High

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Highly cost effective: ``` Focused Manual Spotcheck - Focused manual analysis of source Manual Source Code Review (not inspections)

Automated Static Analysis - Source Code SOAR Partial

According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Source code Weakness Analyzer Context-configured Source Code Weakness Analyzer

Correction automatique Plexicus

Plexicus détecte automatiquement CWE-66 et ouvre une PR de correction en moins de 60 secondes.

Codex Remedium analyse chaque commit, identifie cette faiblesse précise et livre une pull request prête à être relue avec le correctif. Pas de tickets. Pas de transferts.

Obtenir une démo Essayer Plexicus gratuitement
Questions fréquentes

Frequently asked questions

Qu'est-ce que CWE-66 ?

This vulnerability occurs when software incorrectly processes a filename that points to a 'virtual' resource—like a device, pipe, or internal system object—instead of a regular file. The application mistakenly performs file operations (like read, write, or copy) on this non-file resource, which can lead to crashes, data exposure, or unexpected system behavior.

Quelle est la gravité de CWE-66 ?

MITRE n'a pas publié de note de probabilité d'exploitation pour cette faiblesse. Traitez-la comme un impact moyen jusqu'à ce que votre modèle de menace prouve le contraire.

Quels langages ou plateformes sont affectés par CWE-66 ?

MITRE n'a pas spécifié les plateformes affectées pour ce CWE — il peut s'appliquer à la plupart des stacks applicatives.

Comment puis-je prévenir CWE-66 ?

Use safe-by-default frameworks, validate untrusted input at trust boundaries, and apply the principle of least privilege. Cover the data-flow signature in CI with SAST.

Comment Plexicus détecte et corrige CWE-66 ?

Le moteur SAST de Plexicus reconnaît la signature de flux de données de CWE-66 à chaque commit. Lorsqu'une correspondance est trouvée, notre agent Codex Remedium ouvre une PR de correction avec le code corrigé, les tests et un résumé d'une ligne pour le relecteur.

Où puis-je en savoir plus sur CWE-66 ?

MITRE publie la définition canonique à https://cwe.mitre.org/data/definitions/66.html. Vous pouvez également consulter la documentation OWASP et NIST pour des conseils adjacents.

Faiblesses associées

Weaknesses related to CWE-66

CWE-706 Parent

Use of Incorrectly-Resolved Name or Reference

This vulnerability occurs when software uses a name, path, or reference to access a resource, but that identifier points to something…

CWE-178 Frère

Improper Handling of Case Sensitivity

This vulnerability occurs when software fails to consistently handle uppercase and lowercase letters when checking or accessing resources,…

CWE-22 Frère

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

This vulnerability occurs when an application builds a file path using user input but fails to properly validate it, allowing an attacker…

CWE-386 Frère

Symbolic Name not Mapping to Correct Object

This vulnerability occurs when a program uses a fixed symbolic name (like a constant or identifier) to refer to an object, but that name…

CWE-41 Frère

Improper Resolution of Path Equivalence

This vulnerability occurs when an application fails to properly handle different text representations that refer to the same file or…

CWE-59 Frère

Improper Link Resolution Before File Access ('Link Following')

This vulnerability occurs when an application uses a filename to access a file but fails to properly check if that name points to a…

CWE-827 Frère

Improper Control of Document Type Definition

This vulnerability occurs when an application fails to properly restrict which Document Type Definitions (DTDs) can be referenced during…

CWE-98 Frère

Improper Control of Filename for Include/Require Statement in PHP Program ('PHP Remote File Inclusion')

This vulnerability occurs when a PHP application uses unvalidated or insufficiently restricted user input directly within file inclusion…

CWE-67 Enfant

Improper Handling of Windows Device Names

This vulnerability occurs when an application builds file paths from user input but fails to properly recognize or handle Windows reserved…

Ressources

Further reading

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