Show HN: Il2cpp-modder – Generate DLL injection projects for hacking Unity games

https://github.com/juanmjacobs/il2cpp-modder

by juanmjacobs • 6 years ago

69 22 6 years ago

github.com

jareklupinski• 6 years ago

reminds me of my GameShark, maybe it's time to add Moon Jump to a few Unity games?

juanmjacobs4• 6 years ago

definitely!

terramex• 6 years ago

Do many desktop Unity games use IL2Cpp nowadays?

I've hacked and modded a few in the past, but they were all using Mono, so dnSpy could easily decompile them back into source code.

juanmjacobs4• 6 years ago

Hi! I've looked around a few games and more often than not they are using il2cpp. I've also noticed that newer versions of games that used to run mono are now using il2cpp.

gabereiser• 6 years ago

When building a project using IL2CPP, Unity converts IL code from scripts and assemblies to C++, before creating a native binary file (.exe, apk, .xap, for example) for your chosen platform. Some of the uses for IL2CPP include increasing the performance, security, and platform compatibility of your Unity projects.

Mono runtime will load your assembly and bind it with all the pinvoke stuff and JIT.

IL2cpp will take the IL code from your assemblies and convert it to C++ when making the binary, AOT.

IL2cpp is the preferred way to make sure your game supports the most platforms.

pastrami_panda• 6 years ago

IL2cpp is the preferred way to make sure your game supports the most platforms.

Yup, using Mono for iterating due to better build times is pretty common while using il2cpp for production releases.

ARM 64 bit can't even be targeted by Mono so unless you're keen to exhaust the address space il2cpp is the way to go.

BorisTheBrave• 6 years ago

+1 datapoint: I've decompiled several to find out how they work, and found most use mono. Maybe it depends how indie your game is?

My dcompilation writeups can be found here: https://www.boristhebrave.com/category/level-generation/

juanmjacobs4• 6 years ago

Hi, how are you doing? I've recently started diving into reverse engineering stuff. And with all the fuss around Among Us lately, it seemed like a fun thing to hack.

I've noticed that a lot of basic hacks are based on replacing some method implementation to return a fixed value, or do nothing, or writing to some memory position to change the normal game behavior to your advantage. So maybe something like that could be done for Among us.

First I learnt that it was a Unity il2cpp based game and found Il2CppDumper, a great tool for getting class names and method/field offsets in the game. That was great for understanding what I needed to modify. But then I didn't know how to modify it.

So I read a lot of great tutorials here and there and noticed that there were a lot of beginner hackers (like me) struggling with this part. There is quite a bit of low level programming stuff like assembly for function hooking, pointer arithmetics and that sort of thing.

After kinda figuring it out, I've managed to make a simple mod that allowed you to change the speed of the little guy you control by hooking some functions and changing some fields in the player object.

Then it hit me: the process to write the code to perform that sort of mods in any il2cpp based game would be exactly the same. Get your Il2CppDumper output => hook functions => do your modded stuff. So as a personal fun weekend challenge, I decided to make a tool that would be simple to use and would allow anyone to make basic mods without programming at all. And thus, il2cpp-modder was born.

Given the output from Il2CppDumper and some rules telling il2cpp-modder what you'd like to mod, it will generate C++ code to perform DLL injection in your game and run your mods. There are 4 built in mod types: - Make a function return a fixed value (eg, always return true, false, 0, 1, 99999, etc) - Set an object field to any value you want (eg, keep your player health at 100) - Replace a function call arguments (eg, always call your coins setter with 99999) - Replace a function implementation (eg, just rewrite the whole thing. Programming required!)

Maybe this can encourage less experienced hackers to try and make their first successful mods! I really hope this project can help someone. I had a lot of fun building it and I've learned a lot for doing it.

If you have a chance to try it, let me know if you found it useful! Or if you had any trouble I'll try my best to help you.

pfisch4• 6 years ago

Please stop. Your fun little project is going to be used primarily to ruin other people's fun, and make life hard for game devs.

Do you even think about what you are making and what it will be used for?

c-c-c-c-c• 6 years ago

Why would it make life hard for game devs. If you buy a game you own it and can do whatever you like. If you create a mmo game then you cant blindly trust client data and no malice is implied in this post. This is really a non issue and a great way for people to get into programming and hacking.

juanmjacobs4• 6 years ago

Hi there! That's a great point you are making. Of course I can agree that it sucks if a cheater ruins the fun for anyone else.

I'm really not a gamer myself, I just like messing around with code and learning how it all works. There is really a lot to learn from this kind of projects. The content out there on low level programming tends to be a little daunting, arid and hard to understand. So I thought game modding could be a nice package for people to get interested in that kind of skills. The tool generates legible, explained source code and it helps you with the steps for compiling and what not. I think it could be great to motivate beginners to start getting their hands dirty and grasping some of the concepts out there.

I guess most client side hacks (the ones you can make with this tool) are not so great with any modern multiplayer game anyway, as real core domain logic and syncing is often executed server side. And on top of that there is all the basic extra stuff like validations, kicks, bans, anti cheats, etc. For local or single player games, they could work a little better. But what's the harm in that, right? it's just you in there.

Again, even with all that said, I can really see your point, I totally get it! I hope this reply sheds a more positive light on all of this. Have a great day!

syspec• 6 years ago

Would this work for Unity games which are running in WebGL?

mcraiha• 6 years ago

Current Unity browser games generate webassembly as final step.

therein• 6 years ago

Sounds perfect for Rust. :)

Show HN: Il2cpp-modder – Generate DLL injection projects for hacking Unity games

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