> 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/fr/web/dom/xss-dom-via-web-messages.md). # XSS DOM via messages Web Notes sur le XSS DOM via messages Web pour les laboratoires PortSwigger Web Security Academy, y compris le flux de travail d’exploitation, les tests de charge utile, la validation avec Burp Suite et le contexte de remédiation. ### XSS DOM utilisant les messages Web Exploitez une vulnérabilité DOM basée sur XSS sur des messages Web (`postMessage`) pour provoquer le `print()` fonction soit appelée sur la page cible en envoyant une charge utile via le serveur d'exploitation. #### Comportement observé (code source) La page écoute les messages postés et injecte directement le contenu reçu dans `#ads` l'élément sans assainissement :

<script>
   window.addEventListener('message', function(e) {
   document.getElementById('ads').innerHTML = e.data;
   })
</script>

Cela signifie que tout `e.data` reçu sera rendu comme HTML dans `#ads`, ouvrant la porte à un XSS DOM si un attaquant peut publier un message contrôlé.

#### Tests interactifs (console) Exemples de messages envoyés depuis la console du parent / d * message texte simple ```javascript window.parent.postMessage('This is a test'); ```

* injection HTML ```javascript window.parent.postMessage('

hello

'); ```

* test d'alerte (XSS) ```jsx window.parent.postMessage("

"); ```

* provoquer `print()` ( lentille du labo) ```javascript window.parent.postMessage("

"); ```

#### Exploitation via iframe sur le serveur d'exploitation Exemple du HTML hébergé sur votre serveur qui charge la page cible dans une iframe, puis envoie la charge utile lors du chargement de l'iframe : ```mathml ```

Pour déclencher `print()` sur la page cible, envoyez la charge utile contenant `img` élément avec `onerror=print()`: ```html ```

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