Backdoor LUA ?

Should be possible, but do remember that this may also affect your server, and if the plugin is decompiled (or a plain lua file) they can edit that part out (unless you use a good obvuscator)

I assumed your addons are private.

Hello,

Thanks you for the Reply, yes that is the big probleme, if i backdoor my addon, i will infect my client i think.
Today i have user a script that can steal LUA on a server just to understand how that can be possible.

And i got rekt in the Addon folder i have only the vcmod and the ulx but the server have like 60 Addons, so this guyz find a way to protect the server from steal lua, i try to understand how but, that is very strange for me if you have any information, your welcome

have you reversed-engineered the plugin ?
maybe the plugin only check for a sertain folder (simply putting plugins in a different folder would fix this)
I'm not familliair with gmod plugins, but I suggest you check out how the plugin stealer works.