HtB - CA2023 - Hijack

HackTheBox Cyber Apocalypse 2023

The security of the alien spacecrafts did not prove very robust, and you have gained access to an interface allowing you to upload a new configuration to their ship’s Thermal Control System. Can you take advantage of the situation without raising any suspicion?

Solution

We are given a small text-based UI upon connecting to the code via netcat. Enumeration of the code reveals the ability to upload PyYaml scripts encoded in base64.

To exploit this, we’ll simply create a PyYaml payload to cat flag.txt, base64 encode it, and upload that to the server;

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And just like that we receive our flag;

Flag HTB{1s_1t_ju5t_m3_0r_iS_1t_g3tTing_h0t_1n_h3r3?}