CWE-1386 Base Incompleto

Insecure Operation on Windows Junction / Mount Point

This vulnerability occurs when a Windows application opens a file or directory without properly validating that the path is not a symbolic link (junction or mount point) pointing to a location…

Definición

What is CWE-1386?

This vulnerability occurs when a Windows application opens a file or directory without properly validating that the path is not a symbolic link (junction or mount point) pointing to a location outside the application's intended security boundary.
On Windows NTFS file systems, junction points and mount points are types of symbolic links (reparse points) that can redirect file operations from one directory to another, potentially to a completely different drive or privileged location. If an application with elevated privileges opens a file without checking for these links, an attacker can replace the expected file with a link to a sensitive system file, registry key, or named object, tricking the application into performing unauthorized read, write, or delete operations. This allows privilege escalation or data manipulation because the privileged process unknowingly operates on the attacker's target. For example, an attacker could redirect a file operation to AUTOEXEC.BAT, critical configuration files, or security databases, causing the application to corrupt, expose, or modify sensitive data with its own high-level permissions. Developers must explicitly validate paths and handle reparse points to confine operations within the intended directory scope.
Impacto en el mundo real

Real-world CVEs caused by CWE-1386

  • CVE-2021-26426

    Privileged service allows attackers to delete unauthorized files using a directory junction, leading to arbitrary code execution as SYSTEM.

  • CVE-2020-0863

    By creating a mount point and hard links, an attacker can abuse a service to allow users arbitrary file read permissions.

  • CVE-2019-1161

    Chain: race condition (CWE-362) in anti-malware product allows deletion of files by creating a junction (CWE-1386) and using hard links during the time window in which a temporary file is created and deleted.

  • CVE-2014-0568

    Escape from sandbox for document reader by using a mountpoint [REF-1264]

Cómo lo explotan los atacantes

Ruta del atacante paso a paso

  1. 1

    Identifica una ruta de código que maneje entrada no confiable sin validación.

  2. 2

    Crea un payload que ejercite el comportamiento inseguro — inyección, traversal, overflow o abuso de lógica.

  3. 3

    Envía el payload a través de una solicitud normal y observa la reacción de la aplicación.

  4. 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.

Vulnerable pseudo 
// 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

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 prevención

How to prevent CWE-1386

  • Architecture and Design When designing software that will have different rights than the executer, the software should check that files that it is interacting with are not improper hard links or mount points. One way to do this in Windows is to use the functionality embedded in the following command: "dir /al /s /b" or, in PowerShell, use LinkType as a filter. In addition, some software uses authentication via signing to ensure that the file is the correct one to use. Make checks atomic with the file action, otherwise a TOCTOU weakness (CWE-367) can be introduced.
Señales de detección

How to detect CWE-1386

SAST High

Ejecuta análisis estático (SAST) sobre el código buscando el patrón inseguro en el flujo de datos.

DAST Moderate

Ejecuta pruebas dinámicas de seguridad de aplicaciones (DAST) contra el endpoint en vivo.

Runtime Moderate

Vigila los logs en tiempo de ejecución para detectar trazas de excepción inusuales, entradas malformadas o intentos de bypass de autorización.

Code review Moderate

Revisión de código: marca cualquier código nuevo que maneje entrada desde esta superficie sin usar los helpers validados del framework.

Auto-corrección de Plexicus

Plexicus detecta automáticamente CWE-1386 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.

Solicitar demo Probar Plexicus gratis
Preguntas frecuentes

Frequently asked questions

¿Qué es CWE-1386?

This vulnerability occurs when a Windows application opens a file or directory without properly validating that the path is not a symbolic link (junction or mount point) pointing to a location outside the application's intended security boundary.

¿Qué gravedad tiene CWE-1386?

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-1386?

MITRE lists the following affected platforms: Windows.

¿Cómo puedo prevenir CWE-1386?

When designing software that will have different rights than the executer, the software should check that files that it is interacting with are not improper hard links or mount points. One way to do this in Windows is to use the functionality embedded in the following command: "dir /al /s /b" or, in PowerShell, use LinkType as a filter. In addition, some software uses authentication via signing to ensure that the file is the correct one to use. Make checks atomic with the file action,…

¿Cómo detecta y corrige Plexicus CWE-1386?

El motor SAST de Plexicus detecta la firma de flujo de datos para CWE-1386 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-1386?

MITRE publica la definición canónica en https://cwe.mitre.org/data/definitions/1386.html. También puedes consultar la documentación de OWASP y NIST para guías relacionadas.

Debilidades relacionadas

Weaknesses related to CWE-1386

CWE-59 Padre

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-61 Hermano

UNIX Symbolic Link (Symlink) Following

This vulnerability occurs when a software application opens files or directories without properly checking if they are symbolic links…

CWE-62 Hermano

UNIX Hard Link

This vulnerability occurs when an application opens a file or directory without verifying if the name points to a hard link that leads…

CWE-64 Hermano

Windows Shortcut Following (.LNK)

This vulnerability occurs when an application opens a file or directory without properly validating that it is a Windows shortcut (.LNK).…

CWE-65 Hermano

Windows Hard Link

This vulnerability occurs when a Windows application opens a file or directory without properly verifying if the path points to a hard…

Recursos

Further reading

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