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
CWE-66 Base Borrador
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…
Definición
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 en el mundo real
Real-world CVEs caused by CWE-66
-
In IIS, remote attackers can obtain source code for ASP files by appending "::$DATA" to the URL.
-
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+.
-
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.
Cómo lo explotan los atacantes
Ruta del atacante paso a paso
- 1
Identifica una ruta de código que maneje entrada no confiable sin validación.
- 2
Crea un payload que ejercite el comportamiento inseguro — inyección, traversal, overflow o abuso de lógica.
- 3
Envía el payload a través de una solicitud normal y observa la reacción de la aplicación.
- 4
Itera hasta que la respuesta filtre datos, ejecute código del atacante o escale privilegios.
Ejemplo de código vulnerable
Vulnerable pseudo
MITRE no ha publicado un ejemplo de código para esta CWE. El patrón siguiente es ilustrativo — consulta Recursos para referencias canónicas.
// Example pattern — see MITRE for the canonical references.
function handleRequest(input) {
// Untrusted input flows directly into the sensitive sink.
return executeUnsafe(input);
} Ejemplo de código seguro
Secure 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 prevención
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.
Señales de detección
How to detect CWE-66
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
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
According to SOAR [REF-1479], the following detection techniques may be useful: ``` Cost effective for partial coverage: ``` Fuzz Tester Framework-based Fuzzer
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)
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
Plexicus detecta automáticamente CWE-66 y abre un PR de corrección en menos de 60 segundos.
Codex Remedium escanea cada commit, identifica esta debilidad concreta y entrega un pull request listo para revisión con el parche. Sin tickets. Sin traspasos.
Preguntas frecuentes ¿Qué es CWE-66?
¿Qué gravedad tiene CWE-66?
¿Qué lenguajes o plataformas se ven afectados por CWE-66?
¿Cómo puedo prevenir CWE-66?
¿Cómo detecta y corrige Plexicus CWE-66?
¿Dónde puedo aprender más sobre CWE-66?
Frequently asked questions
¿Qué es 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.
¿Qué gravedad tiene CWE-66?
MITRE no ha publicado una calificación de probabilidad de explotación para esta debilidad. Trátala como de impacto medio hasta que tu modelo de amenazas demuestre lo contrario.
¿Qué lenguajes o plataformas se ven afectados por CWE-66?
MITRE no ha especificado plataformas afectadas para esta CWE — puede aplicar a la mayoría de los stacks de aplicaciones.
¿Cómo puedo prevenir 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.
¿Cómo detecta y corrige Plexicus CWE-66?
El motor SAST de Plexicus detecta la firma de flujo de datos para CWE-66 en cada commit. Cuando hay coincidencia, nuestro agente Codex Remedium abre un PR de corrección con el código corregido, las pruebas y un resumen de una línea para el revisor.
¿Dónde puedo aprender más sobre CWE-66?
MITRE publica la definición canónica en https://cwe.mitre.org/data/definitions/66.html. También puedes consultar la documentación de OWASP y NIST para guías relacionadas.
Debilidades relacionadas
Weaknesses related to CWE-66
CWE-706 Padre
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 Hermano
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 Hermano
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 Hermano
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 Hermano
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 Hermano
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 Hermano
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 Hermano
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 Hijo
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
- MITRE — CWE-66 oficial https://cwe.mitre.org/data/definitions/66.html
- State-of-the-Art Resources (SOAR) for Software Vulnerability Detection, Test, and Evaluation https://www.ida.org/-/media/feature/publications/s/st/stateoftheart-resources-soar-for-software-vulnerability-detection-test-and-evaluation/p-5061.ashx
Listo cuando tú lo estés
Deja de pagar por desarrollador.
Empieza a cerrar el bucle.
Plexicus es el ASPM nativo de IA que escanea, filtra, corrige, pentestea y explica — de forma autónoma. Desarrolladores ilimitados, repos ilimitados, acciones de IA de uso justo. Nivel gratuito real, €269/mo anual cuando estés listo.