hc0n Christmas CTF - 2019

Enumeration
I started enumerating the machine using my tool Legion:

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:


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

With this information and reading the padding oracle vulnerability I was able to exploit it:


Set user admin:

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