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.)
CWE-647 Variante Incompleto
Use of Non-Canonical URL Paths for Authorization Decisions
This vulnerability occurs when an application's authorization logic relies on specific URL paths but fails to enforce a single, standardized format. Attackers can bypass access controls by using…
Definición
What is CWE-647?
This vulnerability occurs when an application's authorization logic relies on specific URL paths but fails to enforce a single, standardized format. Attackers can bypass access controls by using alternative, equivalent URL formats that the system doesn't recognize as the same protected resource.
Applications often define access rules for specific URLs, but many different URL formats can point to the same page. If the authorization check doesn't first convert URLs to a canonical (standardized) form, attackers can use variations like different character encodings, case changes, IP addresses instead of domain names, trailing slashes, or explicit port numbers to bypass security checks. Each variation appears different to the authorization system while loading the same protected content.
To prevent this, always normalize URLs to a single canonical format before checking permissions. Implement a default-deny approach that rejects any non-standard URL format. This involves stripping unnecessary elements like default ports, removing trailing slashes, converting to lowercase, decoding encoded characters, and resolving hostnames consistently before any authorization decision is made.
Impacto en el mundo real
Real-world CVEs caused by CWE-647
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
Identifica una ruta de código que maneje entrada no confiable sin validación.
- 2
Crea un payload que ejercite el comportamiento inseguro — inyección, traversal, overflow o abuso de lógica.
- 3
Envía el payload a través de una solicitud normal y observa la reacción de la aplicación.
- 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.
// 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
// 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-647
- Architecture and Design Make access control policy based on path information in canonical form. Use very restrictive regular expressions to validate that the path is in the expected form.
- Architecture and Design Reject all alternate path encodings that are not in the expected canonical form.
Señales de detección
How to detect CWE-647
CWE-647
Don't catalog this weakness. Prove it's reachable.
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Preguntas frecuentes ¿Qué es CWE-647?
¿Qué gravedad tiene CWE-647?
¿Qué lenguajes o plataformas se ven afectados por CWE-647?
¿Cómo puedo prevenir CWE-647?
¿Cómo detecta y corrige Plexicus CWE-647?
¿Dónde puedo aprender más sobre CWE-647?
Frequently asked questions
¿Qué es CWE-647?
This vulnerability occurs when an application's authorization logic relies on specific URL paths but fails to enforce a single, standardized format. Attackers can bypass access controls by using alternative, equivalent URL formats that the system doesn't recognize as the same protected resource.
¿Qué gravedad tiene CWE-647?
MITRE califica la probabilidad de explotación como Alta — esta debilidad se explota activamente en la práctica y debe priorizarse para su remediación.
¿Qué lenguajes o plataformas se ven afectados por CWE-647?
MITRE lists the following affected platforms: Web Server.
¿Cómo puedo prevenir CWE-647?
Make access control policy based on path information in canonical form. Use very restrictive regular expressions to validate that the path is in the expected form. Reject all alternate path encodings that are not in the expected canonical form.
¿Cómo detecta y corrige Plexicus CWE-647?
El motor SAST de Plexicus detecta la firma de flujo de datos para CWE-647 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-647?
MITRE publica la definición canónica en https://cwe.mitre.org/data/definitions/647.html. También puedes consultar la documentación de OWASP y NIST para guías relacionadas.
Debilidades relacionadas
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