CWE-105 Variante Borrador

Struts: Form Field Without Validator

This vulnerability occurs when a Struts application form contains an input field that lacks a corresponding validator, leaving it open to unverified user input.

Definición

What is CWE-105?

This vulnerability occurs when a Struts application form contains an input field that lacks a corresponding validator, leaving it open to unverified user input.
Leaving even one form field without validation creates a direct opening for attackers. They can exploit this oversight to inject malicious data, bypass security checks, or manipulate application logic, potentially leading to data breaches, unauthorized access, or system compromise. While Java applications themselves are often protected from low-level memory issues, the risk escalates if the application interacts with native code or external systems. An attacker could use this unvalidated input as an entry point to trigger buffer overflows or other critical vulnerabilities in those connected components, turning a simple input oversight into a severe chained attack.
Impacto en el mundo real

Real-world CVEs caused by CWE-105

Todavía no hay CVEs públicos enlazados a esta CWE en el catálogo de MITRE.

Cómo lo explotan los atacantes

Ruta del atacante paso a paso

  1. 1

    In the following example the Java class RegistrationForm is a Struts framework ActionForm Bean that will maintain user input data from a registration webpage for an online business site. The user will enter registration data and, through the Struts framework, the RegistrationForm bean will maintain the user data in the form fields using the private member variables. The RegistrationForm class uses the Struts validation capability by extending the ValidatorForm class and including the validation for the form fields within the validator XML file, validator.xml.

  2. 2

    The validator XML file, validator.xml, provides the validation for the form fields of the RegistrationForm.

  3. 3

    However, in the previous example the validator XML file, validator.xml, does not provide validators for all of the form fields in the RegistrationForm. Validator forms are only provided for the first five of the seven form fields. The validator XML file should contain validator forms for all of the form fields for a Struts ActionForm bean. The following validator.xml file for the RegistrationForm class contains validator forms for all of the form fields.

Ejemplo de código vulnerable

Vulnerable XML

The validator XML file, validator.xml, provides the validation for the form fields of the RegistrationForm.

Vulnerable XML 
<form-validation>
  	<formset>
  		<form name="RegistrationForm">
  			<field property="name" depends="required">
  				<arg position="0" key="prompt.name"/>
  			</field>
  			<field property="address" depends="required">
  				<arg position="0" key="prompt.address"/>
  			</field>
  			<field property="city" depends="required">
  				<arg position="0" key="prompt.city"/>
  			</field>
  			<field property="state" depends="required,mask">
  				<arg position="0" key="prompt.state"/>
  				<var>
  					<var-name>mask</var-name>
  					<var-value>[a-zA-Z]{2}</var-value>
  				</var>
  			</field>
  			<field property="zipcode" depends="required,mask">
  				<arg position="0" key="prompt.zipcode"/>
  				<var>
  					<var-name>mask</var-name>
  					<var-value>\d{5}</var-value>
  				</var>
  			</field>
  		</form>
  	</formset>
  </form-validation>
Ejemplo de código seguro

Secure XML

However, in the previous example the validator XML file, validator.xml, does not provide validators for all of the form fields in the RegistrationForm. Validator forms are only provided for the first five of the seven form fields. The validator XML file should contain validator forms for all of the form fields for a Struts ActionForm bean. The following validator.xml file for the RegistrationForm class contains validator forms for all of the form fields.

Seguro XML 
<form-validation>
  	<formset>
  		<form name="RegistrationForm">
  			<field property="name" depends="required">
  				<arg position="0" key="prompt.name"/>
  			</field>
  			<field property="address" depends="required">
  				<arg position="0" key="prompt.address"/>
  			</field>
  			<field property="city" depends="required">
  				<arg position="0" key="prompt.city"/>
  			</field>
  			<field property="state" depends="required,mask">
  				<arg position="0" key="prompt.state"/>
  				<var>
  					<var-name>mask</var-name>
  					<var-value>[a-zA-Z]{2}</var-value>
  				</var>
  			</field>
  			<field property="zipcode" depends="required,mask">
  				<arg position="0" key="prompt.zipcode"/>
  				<var>
  					<var-name>mask</var-name>
  					<var-value>\d{5}</var-value>
  				</var>
  			</field>
  			<field property="phone" depends="required,mask">
  				<arg position="0" key="prompt.phone"/>
  				<var>
  					<var-name>mask</var-name>
  					<var-value>^([0-9]{3})(-)([0-9]{4}|[0-9]{4})$</var-value>
  				</var>
  			</field>
  			<field property="email" depends="required,email">
  				<arg position="0" key="prompt.email"/>
  			</field>
  		</form>
  	</formset>
  </form-validation>
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-105

  • Implementation Validate all form fields. If a field is unused, it is still important to constrain it so that it is empty or undefined.
Señales de detección

How to detect CWE-105

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-105 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-105?

This vulnerability occurs when a Struts application form contains an input field that lacks a corresponding validator, leaving it open to unverified user input.

¿Qué gravedad tiene CWE-105?

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-105?

MITRE lists the following affected platforms: Java.

¿Cómo puedo prevenir CWE-105?

Validate all form fields. If a field is unused, it is still important to constrain it so that it is empty or undefined.

¿Cómo detecta y corrige Plexicus CWE-105?

El motor SAST de Plexicus detecta la firma de flujo de datos para CWE-105 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-105?

MITRE publica la definición canónica en https://cwe.mitre.org/data/definitions/105.html. También puedes consultar la documentación de OWASP y NIST para guías relacionadas.

Debilidades relacionadas

Weaknesses related to CWE-105

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CWE-108 Hermano

Struts: Unvalidated Action Form

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CWE-1174 Hermano

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This vulnerability occurs when an ASP.NET application either completely bypasses the built-in model validation system or implements it…

CWE-554 Hermano

ASP.NET Misconfiguration: Not Using Input Validation Framework

This vulnerability occurs when an ASP.NET application fails to implement a structured input validation framework, relying instead on…

Recursos

Further reading

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