https://clswhre.github.io/ A technical blog documenting infrastructure experiments, networking security, and "Learn in Public" journey. 2026-08-21T22:32:37+03:00 Bohdan Kryzhov https://clswhre.github.io/ Jekyll © 2026 Bohdan Kryzhov /assets/img/favicons/favicon.ico /assets/img/favicons/favicon-96x96.png 2026-06-21T21:00:00+03:00 2026-08-21T22:32:06+03:00 https://clswhre.github.io/posts/June-Recap/ Bohdan Kryzhov

June turned out to be packed: from building my first homelab to attending a Summer Cyber School. Building a Vulnerable Machine Instead of deploying vulnerable machines directly on my home network, I designed an isolated architecture based on the Jump Box model. Network topology: Client / Attacker: laptop running Arch. Hypervisor: a Debian 13 server acting as a bridge. Isolation: insid...

2026-06-21T11:00:00+03:00 2026-08-21T22:32:06+03:00 https://clswhre.github.io/posts/Reverse-Engineering/ Bohdan Kryzhov

During the Summer School I wrote about earlier, we were told that it’s possible to join the university’s CTF team (OSINT, web, reverse, etc.). That caught my interest, so with some background in C and Assembly, I decided to dive into it. Case 1: Static Analysis & Writing a Keygen (Ghidra + C) The first task was to analyze a binary that required entering a valid license key based on a user...