Defense in the Age of Agents

Agents compress reasoning. Attackers already use it.

Human attention doesn’t scale with compute. The only way to keep up is the same density of reasoning on defense: defenders directing agents of their own.

Source · GreyNoise, 9 September 2026

This guide is where to start.

1. 1

   Part 1:The field is changing

   Agents pack years of thinking into days, and attackers already use them. What that changes about your job, and why to start now.

2. 2

   Part 2:What you’ll learn

   The nine systems every defensive agent is built from, so you know what you’re building toward.

3. 3

   Part 3:Five first ideas

   Five ideas to start building with, one page each, each with a free article and video.

4. 4

   Part 4:Where to start

   Six steps from a job you already do to a first agent you can check.

Who’s writing

Faan Rossouw

Security researcher and instructor

I’m a security researcher and instructor. I’ve taught thousands of defenders to find adversaries in network and endpoint telemetry, and earlier in my career I developed offensive security tooling and taught courses on that too.

When agents arrived, I went looking for a course that taught how to build with them from the foundations up. It didn’t exist, so I built my own agentic defense system and turned what I learned into AionSec: the course I couldn’t find.

Speaker & trainer at

• “

  One of the best training classes I've taken in years.

  Jack A. · Security Analyst

• “

  The course is clear, well-structured, and presented with a strong, confident grasp of the material.

  Marc-Andre L. · Cybersecurity Advisor

• “

  Faan's in-depth knowledge and his amazing way of explaining things in the KISS format makes complex topics genuinely accessible.

  Amarjit L. · Threat Emulation Lead