Uploading a backdoored addon.

[AnAsianHacker]

How do we upload files to the server like I can download the server's addon if they are in the server addon but how do I upload stuff

[Renamon Toast Crunch]

How do we upload files to the server like I can download the server's addon if they are in the server addon but how do I upload stuff

What are you trying to upload? Are you the server owner or a server admin with appropriate permissions?
Also, are you trying to upload something that will be server sided or client sided?

[AnAsianHacker]

I basically want to upload a backdoored addon to a server.

[Jaos]

Why would he want to upload something client side when he can just run it from lua_openscript_cl.

[Renamon Toast Crunch]

If i understood his question correctly he wanted to "upload" a file to the server not just run it client side. That's why I asked if he was the server administrator/owner or not. If he was then I could show him where to find the information on uploading specific files to his/her server. But judging by his word choice "backdoored addon" then I'm sure he is just a normal user.

Anyway, look at the game tracker database for server that have either sv_allowcslua set to 1 or sv_cheats set to 1.
You can check the list here on servers with sv_allowcslua set to 1. As @Jaos stated you can run scripts and such using lua_openscript_cl in your console but if what you are trying to use needs server side access then you need an Rcon bypass to get into the servers inner workings.

[AnAsianHacker]

Oh okay./tooshort