How does the injecting things work?

Hey,

thanks, but thats not really what I ment. I ment: How is that done on the programming side of the .dll?
What is exactly happening when I inject something into a process?

depends on how you do it. there are quite a few techniques to achieve that goal. the most common way is to remotely create a thread in a process and load the library (dll) inside the target process with the given msdn(microsoft) functions.

if you want to read more about injections you might want to read about it on wikipedia or stackoverflow.

Theres no Such thing as Undetected dll injector lol there are all Undetected

ScriptHook is too an injected dll, the only difference is, it's using dxinput.dll.
This is a Library which will ussually Loaded from Windows\System32.
But every Programm look first in his own Folder if there is no explicit Path used.
So ScriptHook use a prepared dxinput.dll which is Hooking the DirectX Output and wrap to real dxinput.dll, which is injecting the ScriptHookV.dll for you.
The difference is, ScriptHook invokes Native Functions + the ScriptHandle Thread, because you can only call Functions from this.
The Last Thing (Hooking the ScriptThread) is what is detected, so other Hacks just don't use it, or avoid to write something there.

ScriptHook is Hooking the Functions and the rest dll Hacks use something like this:
which creates a Worker Thread for you, where you can do your shit.