Building a Modern C2 — Introduction to the series
I’m starting a series of technical posts about my Command-and-Control (C2) framework C2TeamServer (repo: https://github.com/maxDcb/C2TeamServer). Over the next articles I’ll walk through the project end-to-end: the teamserver architecture and listeners, the GUI and operator workflows, the implants channels and modules stealth strategies. This first post is a roadmap: what the project is, why I built it, and what I will present in upcoming posts.
Why write this series?
There’s already a lot of high-level C2 analysis and single-technique PoCs out there. My goal is different: to share an engineered, modular C2 implementation with practical, hands-on explanations and a clear look at the architecture decisions behind it. This series is aimed at practitioners who want to understand not just what works, but why it was built that way.
I started this project after taking the CRTO and experimenting with tools like Cobalt Strike. Coming from a C++ development background, I found it instructive to build a complete C2 stack to better understand the mechanics and tradeoffs. I’ve been developing this in my spare time for about two years; the project is now mature enough that it’s worth summarising my work and moving it to the next level — more structure, clearer docs, and tangible examples that others can learn from or contribute to.
What is C2TeamServer
C2TeamServer is my modular C2 framework. At a high level it consists of:
- TeamServer — the central controller that manages listeners, manages sessions, routes messages, and distribute task/output.
- Listeners — network endpoints (HTTP, HTTPS, DNS, SMB, etc.) that accept inbound connections from implants. Listeners easy to develop, pluggable and configurable.
- Implants — agents that connect back to listeners, handles modules to execute tasks (system operation, file transfer, process injection, etc.).
- GUI — a desktop interface to interact with the server, visualize active sessions, author tasks, manage droppers and more.
- Modules — small, testable components (e.g., file transfer, lateral movement, commands) that will be the action executed by an implant.
The repo is organized to favor modularity.
Audience & prerequisites
This series assumes:
- Intermediate knowledge of systems programming (principaly C/C++).
- Familiarity with Linux/Windows internals (processes, tokens, networking).
- Comfort reading code, running local labs.
Series roadmap (what to expect)
I’ll break the work into focused posts so each article is deep and thorough.
Part 1 — TeamServer & Architecture (next post)
- Build system
- Messagerie choices
- Handling of listeners
- Interaction with modules
Part 2 — Listeners & network design
- How listeners are implemented and why (HTTP/HTTPS, DNS, TCP raw, named pipes)
Part 3 — GUI & operator workflows
- GUI design goals
- Why I choose python with modularity in mind
Part 4 — Implant design, channels & steal strategies
- Implant architecture
- Channel implementations
- “Steal” strategies
Part 5 — Modules ?
- I don’t know yet
Want to follow along?
- Star and watch the repo: https://github.com/maxDcb/C2TeamServer
- I’ll publish each post to my blog (https://maxdcb.github.io/).
Wrap up
This series will be practical, code-centric. The next post (TeamServer internals and configuration) will dive into the codebase structure, key modules, and show the TeamServer boot flow.
If there’s a specific angle you want me to prioritize (deep dive on a particular transport, UI automation, or implant persistence mechanics), tell me which one and I’ll fold it into the schedule.
Ready? Here is Part 1 — TeamServer & Architecture.