CWE-66 Base Rascunho

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…

Definição

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.
Impacto no mundo real

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.

Como os atacantes a exploram

Trajeto do atacante passo a passo

  1. 1

    Identificar um caminho de código que trata input não confiável sem validação.

  2. 2

    Criar um payload que explora o comportamento inseguro — injeção, traversal, overflow ou abuso de lógica.

  3. 3

    Entregar o payload através de um pedido normal e observar a reação da aplicação.

  4. 4

    Iterar até que a resposta exponha dados, execute código do atacante ou escale privilégios.

Exemplo de código vulnerável

Vulnerable pseudo

A MITRE não publicou um exemplo de código para este CWE. O padrão abaixo é ilustrativo — consulte os Recursos para referências canónicas.

Vulnerável pseudo 
// Example pattern — see MITRE for the canonical references.
function handleRequest(input) {
  // Untrusted input flows directly into the sensitive sink.
  return executeUnsafe(input);
}
Exemplo de código seguro

Secure pseudo

Seguro 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.
Lista de verificação de prevenção

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.
Sinais de deteção

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

Correção automática do Plexicus

O Plexicus deteta automaticamente o CWE-66 e abre um PR de correção em menos de 60 segundos.

O Codex Remedium analisa cada commit, identifica esta fraqueza exata e entrega um pull request pronto para revisão com o patch. Sem tickets. Sem transferências.

Obter uma demonstração Experimente o Plexicus gratuitamente
Perguntas frequentes

Frequently asked questions

O que é o 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.

Qual a gravidade do CWE-66?

A MITRE não publicou uma classificação de probabilidade de exploração para esta fraqueza. Trate-a como impacto médio até o seu modelo de ameaças provar o contrário.

Que linguagens ou plataformas são afetadas pelo CWE-66?

A MITRE não especificou as plataformas afetadas por este CWE — pode aplicar-se à maioria das stacks de aplicações.

Como posso prevenir o 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.

Como é que o Plexicus deteta e corrige o CWE-66?

O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-66 em cada commit. Quando é encontrada uma correspondência, o nosso agente Codex Remedium abre um PR de correção com o código corrigido, testes e um resumo de uma linha para o revisor.

Onde posso saber mais sobre o CWE-66?

A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/66.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.

Fraquezas relacionadas

Weaknesses related to CWE-66

CWE-706 Pai

Use of Incorrectly-Resolved Name or Reference

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CWE-22 Irmão

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CWE-59 Irmão

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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 Irmão

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CWE-98 Irmão

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

CWE-67 Filho

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…

Recursos

Further reading

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