CWE-472 Base Borrador

External Control of Assumed-Immutable Web Parameter

This vulnerability occurs when a web application incorrectly trusts data that appears to be fixed or hidden from the user, such as values in hidden form fields, cookies, or URL parameters. Because…

Definición

What is CWE-472?

This vulnerability occurs when a web application incorrectly trusts data that appears to be fixed or hidden from the user, such as values in hidden form fields, cookies, or URL parameters. Because this data is actually controllable by the client, attackers can modify it to bypass security checks or corrupt application logic.
Web applications often make a critical mistake: they assume that data sent to the client in hidden fields, cookies, or parameters will be returned unchanged. Since all client-side data can be tampered with, this false sense of security leads to improper validation. Attackers exploit this by modifying these assumed-immutable values to escalate privileges, manipulate prices, alter user sessions, or corrupt backend data flows. The core issue is the server's over-reliance on client-provided data for making security decisions. To prevent this, always validate and authorize all user input on the server, regardless of its perceived source or immutability. Treat hidden fields and cookies as untrusted input, just like any other form field. Implementing proper server-side session management and using cryptographic signatures for critical data can help enforce integrity. Managing these validation rules across a complex application is challenging; an ASPM platform like Plexicus can automatically detect these trust violations via DAST and SAST, and its AI can suggest precise code fixes to enforce server-side validation, streamlining remediation.
Impacto en el mundo real

Real-world CVEs caused by CWE-472

  • CVE-2002-0108

    Forum product allows spoofed messages of other users via hidden form fields for name and e-mail address.

  • CVE-2000-0253

    Shopping cart allows price modification via hidden form field.

  • CVE-2000-0254

    Shopping cart allows price modification via hidden form field.

  • CVE-2000-0926

    Shopping cart allows price modification via hidden form field.

  • CVE-2000-0101

    Shopping cart allows price modification via hidden form field.

  • CVE-2000-0102

    Shopping cart allows price modification via hidden form field.

  • CVE-2000-0758

    Allows admin access by modifying value of form field.

  • CVE-2002-1880

    Read messages by modifying message ID parameter.

Cómo lo explotan los atacantes

Ruta del atacante paso a paso

  1. 1

    In this example, a web application uses the value of a hidden form field (accountID) without having done any input validation because it was assumed to be immutable.

  2. 2

    Hidden fields should not be trusted as secure parameters.

  3. 3

    An attacker can intercept and alter hidden fields in a post to the server as easily as user input fields. An attacker can simply parse the HTML for the substring:

  4. 4

    or even just "hidden". Hidden field values displayed later in the session, such as on the following page, can open a site up to cross-site scripting attacks.

Ejemplo de código vulnerable

Vulnerable Java

In this example, a web application uses the value of a hidden form field (accountID) without having done any input validation because it was assumed to be immutable.

Vulnerable Java 
String accountID = request.getParameter("accountID");
  User user = getUserFromID(Long.parseLong(accountID));
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-472

  • Implementation Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
  • Implementation Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.
Señales de detección

How to detect CWE-472

Automated Static Analysis High

Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)

Auto-corrección de Plexicus

Plexicus detecta automáticamente CWE-472 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-472?

This vulnerability occurs when a web application incorrectly trusts data that appears to be fixed or hidden from the user, such as values in hidden form fields, cookies, or URL parameters. Because this data is actually controllable by the client, attackers can modify it to bypass security checks or corrupt application logic.

¿Qué gravedad tiene CWE-472?

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-472?

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

¿Cómo puedo prevenir CWE-472?

Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and…

¿Cómo detecta y corrige Plexicus CWE-472?

El motor SAST de Plexicus detecta la firma de flujo de datos para CWE-472 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-472?

MITRE publica la definición canónica en https://cwe.mitre.org/data/definitions/472.html. También puedes consultar la documentación de OWASP y NIST para guías relacionadas.

Debilidades relacionadas

Weaknesses related to CWE-472

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External Control of File Name or Path

This vulnerability occurs when an application uses unvalidated user input to construct file or directory paths for filesystem operations.

Recursos

Further reading

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