A simple backdoor using Golang as a REST API (for educational purposes):

• /run?command=: Run any shell command. (Windows: PowerShell, Linux: )
• /screenshot: Return a desktop screenshot.
• /stream: Almost realtime screenshot stream
• /system: Provide machine status (RAM, CPU, etc.).
• /procs: Display a list of processes.
• /(index): Serve files.

Notice: I will not be responsible for any risks or illegal usage purposes.