CTF on THALIUM

ECW 2023: Centralized Memory (write-up)

Tue, 07 Nov 2023 12:00:00 +0100

Centralized Memory was a hard Linux pwn challenge created for the European Cyber Week CTF 2023 qualifiers. This write-up covers the intended method of exploitation through a race condition, an AES padding bug and a stack overflow.

ECW 2023: kaleidoscope (write-up)

Tue, 07 Nov 2023 12:00:00 +0100

kaleidoscope was a hard reverse engineering challenge created for the European Cyber Week CTF 2023 qualifiers, with a focus on Windows-specific mechanisms and VM-based obfuscation.

ECW 2023: The Calculator in Shadow (write-up)

Tue, 07 Nov 2023 12:00:00 +0100

The Calculator in Shadow was a hard pwn challenge created for the European Cyber Week CTF 2023 qualifiers. It included exploiting a RISC-V calculator running on top of a customized QEMU that featured a poorly implemented shadow stack.

ECW 2021 - WriteUp

Mon, 25 Oct 2021 12:00:01 +0100

For the European Cyber Week CTF 2021 Thalium created some challenges in our core competencies: reverse and exploitation. This blog post presents some of the write-ups:

Chest (36 solve) - reverse
FSB as a service (3 solve) - exploitation
WYSIWYG (3 solve) - reverse
Pipe Dream (1 solve) - reverse
- the author posted his solution on his personal blog

Thalium’s challenges have been less resolved than others. They were not that difficult, but probably a bit more unexpected. A few additional challenges designed by Thalium are:

Cyber Apocalypse 2021 5/5 - Artillery

Wed, 28 Apr 2021 12:00:04 +0100

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.

Cyber Apocalypse 2021 4/5 - Discovery

Wed, 28 Apr 2021 12:00:03 +0100

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

Cyber Apocalypse 2021 3/5 - Off the grid

Wed, 28 Apr 2021 12:00:02 +0100

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.

Cyber Apocalypse 2021 2/5 - Wii-Phit

Wed, 28 Apr 2021 12:00:01 +0100

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.

Cyber Apocalypse 2021 1/5 - PWN challenges

Wed, 28 Apr 2021 12:00:00 +0100

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: