So, I may have figured out a way to make cheats undetected. (Internal + maybe External)

Step 1. download a file pumper
Step 2. Get an unpopular injector. (you may also pump up a public injector with a file pumper but idk if it's ud too)
Step 3. Get a good leaked/public cheat.
Step 4. Pump Them up.
Step 5. PLAY!!!

This has NOT been tested.
Try only at your own risk.
I've been playing with that method on leaked Intrusi0n.com and, well i've not been banned yet.
i did this for 3 months now.
USE ONLY AT YOUR OWN RISK.

For External cheats:

Step 1. Do steps shown above upto 4.
Step 2. Download a file protector.
Step 3. Launch csgo.
Step 4. Launch the external cheat through the file protector.
Step 5. don't be obvious and play.