What is it?

CTF is a competitive hacking event, similar to IOI or ICPC, but in the domain of cybersecurity. Teams usually face a number of challenges about cryptography, binary reverse engineering and exploitation, web vulnerabilities, digital forensics, etc.

Each challenge has a relatively well-defined goal (e.g. exploiting an insecure cryptographic protocol), and reaching that goal allows the contestants to uncover (capture) a flag, which is some secret string like TBTL{Th15_15_4_Dummy_Fl4g}. The team then submits a flag in exchange for points. The team with the most points wins.

Basically, being successful at a CTF competition entails having a deep understanding of computer systems and security.

This particular CTF is organized by the employees of TBTL (The Blockhouse Technology Limited) Zagreb, with the main goal being connecting with talent in Croatia that has an interest in the field of cybersecurity.

When is it?

The event starts at midnight on May 11th 2024 CEST and lasts for 48 hours.

Registration will open at least 72 hours before the contest starts.

Competition Format

The competition consists of a bunch of challenges divided into the following five categories (standard Jeopardy format):

Rules and Fair Play


We will reward the best Croatian team and the best Croatian university team with a 200€ Amazon voucher.