How to find backdoors?

Yeah like others have explained backdoors can be anywhere, they can also be obfuscated too, making them harder to spot for the unexperienced, they can be hidden anywherere in a .lua file,
if you find anything access _G the global table and looks like a garbled mess, it's most likely a backdoor.

I'm gonna link my own thread. https://nulledbb.com/thread-Has-your-ser...Backdoored

I would suggest downloading a community made backdoor finder specifically made for addons but I recommend "https://gmodaddons.com/scanner" as it is a great way to find backdoors, I suggest you check it out yourself.

Oh, backdoor, very hard find, backdoor can break you server

Lakeey had solid post about it. Easiest way would be another addon to check it, or analyze it yourself as acoder.

backdoor can be pretty hard to find my friend said

I recommend "https://gmodaddons.com/scanner" as it is a great way to find backdoors

Use CPE to scan for backdoors, it tells you what file its in and what line its on so you can delete it.

use virustotal to scan addon for backdoors ! this is good think!

very good tread to be started just downloaded CPE and going to give this a look now