Artillery was a web challenge of the Cyber Apocalypse 2021 CTF organized by HackTheBox. We were given the source code of the server to help us solve the challenge. This challenge was a nice opportunity to learn more about XXE vulnerabilities.

One of the least solved challenges, yet probably not the most difficult one. It is a Hardware challenge, though it is significantly different from the other challenges of this category. The first thing to spot is that when starting the challenge machine, we have access to two network services:

• an HTTP server, requesting an authentication
• an AMQP broker, rabbitmq

Off-the-grid was the 4th hardware challenge of the Cyber Apocalypse 2021 CTF organized by HackTheBox. We were given an Saleae trace and schematics to analyse. Thalium was one of the very first of 99 players to complete it.

Wii-Phit was the only Hard crypto challenge designed by CryptoHack for the Cyber Apocalypse 2021 CTF (there were also 4 challenges categorized as Insane though).

There is already an excellent writeup by the challenge organizers: one could recognize a well known equation related to the Erdős–Straus conjecture, some participants used Z3. We took a different approach.

Thalium participated in the Cyber Apocalypse 2021 CTF organized last week by HackTheBox. It was a great success with 4,740 teams composed of around 10,000 hackers from all over the world. Our team finished in fifth place and solved sixty out of the sixty-two challenges:

This article explains how we solved each pwn challenge and what tools we used, it is written to be accessible to beginners: