[Crypt]

Say you got one of your "friends" to run a reverse shell script on their PC that connects to your server, giving you a shell on their PC. How would you backdoor their computer in a way that you could just connect to their PC or whatever and get a shell?

The only thing I could really think of is making some sort of script run at start up of the machine, but that would mean you'd have to be listening at the right time to get the shell.