About

Hey there! I’m Šimon Šustek, AKA Sijisu.

I study Computer Science at the Faculty of Mathematics and Physics, Charles University in Prague.

I currently also work as an independent security researcher, with focus on web, AI and binary security and their interactions. I’m interested in both AI for Security (hackbots, etc.) and Security for AI (jailbreaks, etc.).

I’ve pretty much retired from CTFs just as the Opus 4.6 and GPT o3 AI wave hit, but I still think CTFs are a good way to get into security and computer science in general even now. Over the years, I’ve enjoyed playing CTFs with WreckTheLine, the Czech National ECSC Team (2019, 2022, 2023 and 2024, 2025 as captain) and ENISA Team Europe (2022, 2023). I’ve also created challenges for the ECSC 2021 in Prague. I’m very grateful for all these experiences and connections I’ve had the chance to make through CTFs.

I’ve co-created the Pitfalls of Computer Security course at my university together with Honza and Martin, where we try to teach student how to think like hackers.

If you want to get in touch about anything, or see my CV (with other achievements and experience), just write me an email at the address below.

Contact me

Email: mail@sijisu.eu

Gitlab: @sijisu