> 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-vulnerabilities/api-attack/authentication-api-pentesting-web.md).

# Authentifizierungs-API

## API-Authentifizierung

Zum Einloggen:

```json
curl -s -X POST http://secret.htb:3000/api/user/login -H "Content-Type: application/json" -d '{
    "email": "jordan@htb.com",
    "password": "jordan"
}' ; echo

```

Dies gibt ein Authentifizierungs-Token zurück (`auth-token`). `eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJfaWQiOiI2NzIxZjE5ZmQ4YWMzZTA0NjMxZjc4NmQiLCJuYW1lIjoiam9yZGFuIiwiZW1haWwiOiJqb3JkYW5AaHRiLmNvbSIsImlhdCI6MTczMDI3ODEyM30.z6quBZ6bTMSrkl7NxIfLEL0gUw6Wjvm3HWdnlhZBUoQ`

<figure><img src="/files/61210032e19bed07e6c6265948586d381c69b20a" alt=""><figcaption></figcaption></figure>

### Standardmäßige Überprüfung des JSON-Body

<figure><img src="/files/c7c3b7bc9c63d86bba42555563a219991f637375" alt="" width="563"><figcaption></figcaption></figure>

`email: "root@dasith.works"` `password: "Kekc8swFgD6zU"`

<figure><img src="/files/1ae3a6128cf1a1fcf6d72595e00a2e84915def97" alt=""><figcaption></figcaption></figure>

### Überprüfungsschwachstelle [JSON-Web-Token](/de/web-vulnerabilities/json-web-token-jwt-attack.md)

Verwenden Sie eine Website, um das JWT zu dekodieren und seinen Inhalt zu lesen und zu manipulieren.

> **Hinweis**: Das JWT-Token sollte ungültig sein. Durch das Ändern der Felder "name" und "email" auf Administratorwerte:

{% embed url="<https://jwt.io/>" %}

<figure><img src="/files/adcc97e20c02708df43999e04bf2fdd25f7ba858" alt=""><figcaption></figcaption></figure>

`"name": "theadmin",` `"email": "root@dasith.works",` `eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJfaWQiOiI2NzIxZjE5ZmQ4YWMzZTA0NjMxZjc4NmQiLCJuYW1lIjoidGhlYWRtaW4iLCJlbWFpbCI6InJvb3RAZGFzaXRoLndvcmtzIiwiaWF0IjoxNzMwMjc4MTIzfQ.yn6hXmpBxrfb5TMDY4_6zirckzlhnQP_L_YWb4wL2Ug`

<figure><img src="/files/db0182eb52faf509bfa4efe9f30b539c2d375ce5" alt=""><figcaption></figcaption></figure>

### Zugriffsversuch auf eine private API:

Versuch, mit dem modifizierten JWT auf eine private API zuzugreifen:

{% code overflow="wrap" %}

```bash
curl -s -X GET "http://secret.htb:3000/api/priv" -H "auth-token: eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJfaWQiOiI2NzIxZjE5ZmQ4YWMzZTA0NjMxZjc4NmQiLCJuYW1lIjoidGhlYWRtaW4iLCJlbWFpbCI6InJvb3RAZGFzaXRoLndvcmtzIiwiaWF0IjoxNzMwMjc4MTIzfQ.yn6hXmpBxrfb5TMDY4_6zirckzlhnQP_L_YWb4wL2Ug" | jq

```

{% endcode %}

Wir erhalten die Meldung "invalid token".

<figure><img src="/files/400011e0e5401c96a3a5bf45df0c3becf888c210" alt="" width="563"><figcaption></figcaption></figure>

Mit unserem eigenen JWT haben wir als normaler Benutzer Zugriff:

{% code overflow="wrap" %}

```bash
curl -s -X GET "http://secret.htb:3000/api/priv" -H "auth-token: eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJfaWQiOiI2NzIxZjE5ZmQ4YWMzZTA0NjMxZjc4NmQiLCJuYW1lIjoiam9yZGFuIiwiZW1haWwiOiJqb3JkYW5AaHRiLmNvbSIsImlhdCI6MTczMDI3ODEyM30.z6quBZ6bTMSrkl7NxIfLEL0gUw6Wjvm3HWdnlhZBUoQ" | jq

```

{% endcode %}

Wir erhalten die Meldung "You are normal user".

<figure><img src="/files/d72b59a30f314c4d4c996e1486037392f2415679" alt=""><figcaption></figcaption></figure>


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