CWE-221 Clase Incompleto

Information Loss or Omission

This weakness occurs when an application fails to log critical security events or records them inaccurately, which can misguide security decisions and hinder incident investigation.

Definición

What is CWE-221?

This weakness occurs when an application fails to log critical security events or records them inaccurately, which can misguide security decisions and hinder incident investigation.
When a system doesn't capture key details like authentication failures, access violations, or input errors, security teams lose the visibility needed to detect and respond to attacks. This omission creates blind spots, making it difficult to understand an attack's origin, method, and impact, ultimately weakening your security posture. This problem can also be a side effect of another vulnerability. For instance, a severe issue like a buffer overflow might cause a program to crash abruptly before it has a chance to write any log entry about the anomalous event. This means the root cause remains hidden, complicating forensic analysis and delaying the fix for the underlying flaw.
Impacto en el mundo real

Real-world CVEs caused by CWE-221

  • CVE-2004-2227

    Web browser's filename selection dialog only shows the beginning portion of long filenames, which can trick users into launching executables with dangerous extensions.

  • CVE-2003-0412

    application server does not log complete URI of a long request (truncation).

  • CVE-1999-1029

    Login attempts are not recorded if the user disconnects before the maximum number of tries.

  • CVE-2002-0725

    Attacker performs malicious actions on a hard link to a file, obscuring the real target file.

  • CVE-1999-1055

    Product does not warn user when document contains certain dangerous functions or macros.

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 PHP

This code logs suspicious multiple login attempts.

Vulnerable PHP 
function login($userName,$password){
  		if(authenticate($userName,$password)){
  			return True;
  		}
  		else{
  			incrementLoginAttempts($userName);
  			if(recentLoginAttempts($userName) > 5){
  				writeLog("Failed login attempt by User: " . $userName . " at " + date('r') );
  			}
  		}
  }
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-221

  • 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-221

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-221 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-221?

This weakness occurs when an application fails to log critical security events or records them inaccurately, which can misguide security decisions and hinder incident investigation.

¿Qué gravedad tiene CWE-221?

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-221?

MITRE no ha especificado plataformas afectadas para esta CWE — puede aplicar a la mayoría de los stacks de aplicaciones.

¿Cómo puedo prevenir CWE-221?

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-221?

El motor SAST de Plexicus detecta la firma de flujo de datos para CWE-221 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-221?

MITRE publica la definición canónica en https://cwe.mitre.org/data/definitions/221.html. También puedes consultar la documentación de OWASP y NIST para guías relacionadas.

Debilidades relacionadas

Weaknesses related to CWE-221

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CWE-404 Hermano

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Recursos

Further reading

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