I read The Rootkit Arsenal[0] while I was taking my first assembly language course and operating systems class. The author did an amazing job of making the material interesting, approachable, and as clear as machine code hex can ever really be. Highly recommend if you have any interest in the guts of operating systems and how to tear them apart.

[0] https://www.amazon.com/Rootkit-Arsenal-Escape-Evasion-Corner...