RATel

RAT-el is an open source penetration test tool that allows you to take control of a windows machine. It works on the client-server model, the server sends commands and the client executes the commands and sends the result back to the server. The client is completely undetectable by anti-virus software. Maintained by FrenchCisco on GitHub, where it has earned 277 stars from the community.

It's actively developed around bypass-av, cybersecurity, hacking, and is a solid reference for anyone building with these tools.