Another one - http://gtm.steamproxy.vip/sharedfiles/filedetails/?id=1076978429

Found another
https://gtm.steamproxy.vip/sharedfiles/filedetails/?id=918339073

I remember this being posted on FacePunch so I doubt it would have a backdoor or anything and looking through the code it has nothing of the sort.

HTX backdoors:


RunString backdoors:


Promotion backdoors:


Malicious addons:
http://gtm.steamproxy.vip/sharedfiles/filedetails/?id=683840016
http://gtm.steamproxy.vip/sharedfiles/filedetails/?id=1076978429

That's still there, just this is faster as you don't have to subscribe to the addon, you can download and extract it with one button press.

Download the latest version for your OS - https://github.com/FPtje/gmosh/releases

When downloaded run "setup.exe" and once installed open the program.

Finally go to the "Workshop tools" tab and paste the id for the addon you want to download and click "Download"!

Now you can easily download the source for addons at will.

A http.Fetch/Post blocker? Derma html blocker or both?

Well you're in luck as I've released an addon to combat that!
http://gtm.steamproxy.vip/sharedfiles/filedetails/?id=845376492
It'll block connect from singleplayer and attempt to tell you which addon tried to redirect you!

VAC can't work on Garry's Mod because it wouldn't be able to tell whether you should be running that Lua script or not.
Garry made GAC but then that got removed/doesn't do anything. There are a few really old cheats like Seth hack which might get you banned though, but that's about it.

If VAC/GAC worked in Garry's Mod then there wouldn't be so many Lua anti-cheat addons.

You can't get VAC banned for any Lua in Gmod. Next!