How do you find backdoor's in addons

1. Try running nomalua (Link: https://github.com/THABBuzzkill/nomalua) just keep in mind there are always many false positives.
2. Look through suspicious addons (and always check any new ones you get) particularly go to \lua\autorun and check the autorun file, that's where most people put backdoors. Something like a link is a dead giveaway.
3. Keep in mind you are never fully safe from backdoors unless you thoroughly check every file and know a bit about coding. The easiest way to find a backdoor is never get an addon with one in the first place. So buying your own addons for guaranteed safety or at the least if you download leaks, make sure they are from a respected user of the forums (usually this means the link will require credits but its a rightful tradeoff)