CWE-290 Base Incompleto

Authentication Bypass by Spoofing

This weakness occurs when an application's authentication system can be tricked into accepting forged or manipulated credentials, allowing unauthorized access without proper verification.

Definición

What is CWE-290?

This weakness occurs when an application's authentication system can be tricked into accepting forged or manipulated credentials, allowing unauthorized access without proper verification.
Authentication bypass by spoofing happens when an application fails to properly verify the source or integrity of authentication data. Instead of robustly checking credentials, the system might accept falsified information from network packets, certificates, session tokens, or identity claims. This allows attackers to impersonate legitimate users by crafting fake authentication artifacts that the flawed validation logic incorrectly approves. Common root causes include trusting easily forged data like IP addresses or HTTP headers for identity, using weak cryptographic signatures, or failing to validate the entire authentication chain. To prevent this, developers must implement complete credential verification using cryptographically secure methods, never rely on client-supplied data alone for identity, and ensure all authentication tokens are properly signed and validated on the server side.
Impacto en el mundo real

Real-world CVEs caused by CWE-290

  • CVE-2022-30319

    S-bus functionality in a home automation product performs access control using an IP allowlist, which can be bypassed by a forged IP address.

  • CVE-2009-1048

    VOIP product allows authentication bypass using 127.0.0.1 in the Host header.

Cómo lo explotan los atacantes

Ruta del atacante paso a paso

  1. 1

    The following code authenticates users.

  2. 2

    The authentication mechanism implemented relies on an IP address for source validation. If an attacker is able to spoof the IP, they may be able to bypass the authentication mechanism.

  3. 3

    Both of these examples check if a request is from a trusted address before responding to the request.

  4. 4

    The code only verifies the address as stored in the request packet. An attacker can spoof this address, thus impersonating a trusted client.

  5. 5

    The following code samples use a DNS lookup in order to decide whether or not an inbound request is from a trusted host. If an attacker can poison the DNS cache, they can gain trusted status.

Ejemplo de código vulnerable

Vulnerable Java

The following code authenticates users.

Vulnerable Java 
String sourceIP = request.getRemoteAddr();
  if (sourceIP != null && sourceIP.equals(APPROVED_IP)) {
  	authenticated = true;
  }
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-290

  • 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-290

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-290 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.

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Preguntas frecuentes

Frequently asked questions

¿Qué es CWE-290?

This weakness occurs when an application's authentication system can be tricked into accepting forged or manipulated credentials, allowing unauthorized access without proper verification.

¿Qué gravedad tiene CWE-290?

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-290?

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

¿Cómo puedo prevenir CWE-290?

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-290?

El motor SAST de Plexicus detecta la firma de flujo de datos para CWE-290 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-290?

MITRE publica la definición canónica en https://cwe.mitre.org/data/definitions/290.html. También puedes consultar la documentación de OWASP y NIST para guías relacionadas.

Debilidades relacionadas

Weaknesses related to CWE-290

CWE-1390 Padre

Weak Authentication

This vulnerability occurs when a system's login or identity verification process is too easy to bypass or fool. While it attempts to check…

CWE-1391 Hermano

Use of Weak Credentials

This vulnerability occurs when a system relies on weak authentication credentials—like default passwords, hard-coded keys, or easily…

CWE-262 Hermano

Not Using Password Aging

This vulnerability occurs when a system lacks password expiration policies, allowing users to keep the same password indefinitely.

CWE-263 Hermano

Password Aging with Long Expiration

The system enforces password changes, but the time allowed between changes is excessively long, weakening security.

CWE-289 Hermano

Authentication Bypass by Alternate Name

This vulnerability occurs when a system checks access based on a resource or user name, but fails to account for all the different names…

CWE-294 Hermano

Authentication Bypass by Capture-replay

This vulnerability occurs when an attacker can intercept and record legitimate authentication traffic, then replay it later to gain…

CWE-301 Hermano

Reflection Attack in an Authentication Protocol

A reflection attack is a flaw in mutual authentication protocols that allows an attacker to impersonate a legitimate user without knowing…

CWE-302 Hermano

Authentication Bypass by Assumed-Immutable Data

This vulnerability occurs when an authentication system incorrectly treats certain data as unchangeable, when in fact an attacker can…

CWE-303 Hermano

Incorrect Implementation of Authentication Algorithm

This weakness occurs when a developer implements a standard authentication algorithm, but makes critical mistakes in the code that cause…

Recursos

Further reading

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