I doubt that roblox would remove this. For one, the corescripts folder is still in the versions, and if they removed corescripts, why would it be there? Also roblox has recently had a hack week showcase and I am fairly certain that people who entered in it used corescripts to achieve/make what they did unless they are all roblox employees who have access/more knowledge about how to change stuff studio.
that was kinda vague, but I hope you get my point
I would try to modify the StarterScript and add your CoreScript there.
Doesn’t work in Studio anymore… I removed the CoreScripts folder in the Studio folder client, and the scripts still load
Oh, so if I wanted to change roblox studio, I would just change the default scripts that are found in that version. Before I though you meant modify a starter script inside the core script folder but I guess you meant in a default script folder. I will try this out when I get the chance to 
. Also thanks for pointing that out @Danny73244
You’re probably using the wrong version
(Sorry im late)
Is there a currently known way to do this as of 2022? I want to test some of Roblox’s private services.
Most likely not, and those services are only meant to be used by Roblox not normal users.
Wow, I found it. I wonder if I can change the code in the CoreScripts without getting banned.
Edit: I found how to register a string for StarterGui:SetCore().
Edit 2: Could you use custom CoreScripts to defend against exploiters?
Core scripts are client side only, so no.
Really? I found a folder called “ServerCoreScripts”.
By client sided I mean only to your client. That’s why it’s considered exploiting.
How, can you share how you achieved this?
Sure. The method is StarterGui:RegisterSetCore().
The parameters are the string and a function.
This is only accessible to CoreScripts
patched??? dosent work bruhhhhhhhhhhhhhhhhhhhhhhhhhhhh
I mean a CoreScript is supposed to be used only by Roblox and also this topic was created almost 4 years ago.
maybe because CoreScripts now load from DataModelPatch.rbxm instead of ExtraContent/scripts
Just compile some luau and inject the compile result into there via a hex editor.
It has to be raw byte codes, not luau asm.
messing it up will result in the RAM-eating WSOD