This post starts a series of a few dedicated to my work on exploiting the Source Engine 1 - back in 2022-2023. At the time, CS2 was not out yet, hence, the primary target was still CS:GO. In the course of these posts, I’ll talk about the few bugs that I found and how I exploited them to get remote code execution - particularly targeting CS:GO. Especially, I’ll be focusing on the network protocol of the engine, and dwelve into its internals.