Discussion Coding bases | Lua | Unity | Frida | Java

[RedMundo]

Hello,

I've been experimenting with hacking and have gotten some results (yes, I got banned! ). What initially drew me to this was modding and creating QoL (Quality of Life) features that developers wouldn't implement for us. After addressing enough QoL improvements, I became curious about hacking, and here I am.

Let me go straight to the point with my questions. However, feel free to share your experiences or the methods you used to "fix" similar issues.

---

1. Game A​

I believe this game uses Lua 5.1, but it might also involve LuaJIT. This is where I feel my lack of fundamental coding knowledge. I don’t think LuaJIT is a type of encryption, but I’m unsure about the correct terms. After dumping code from luaL_loadbuffer, I had to convert the output into Lua-readable files.

Code to Intercept and Modify Code (Frida):​

Using Frida, I intercept libslua’s luaL_loadbuffer function to extract the game logic (classes and methods). Once the target function is found, I inject or replace the code.

• Example of a Game Function: (side note: 2 files)
  

  -- root/../../ArtifactCat.lua
  ArtifactCat = class(BaseCat)
  
  function ArtifactCat:ctor()
  
      self._init_Cat_Pos = Vector3(0, 0, 0)
      self._Cat_Pos = nil
  end
  function ArtifactCat:GetArtSide()
      local artInfo = zzArtMgr:GetArtInfo()
  
      if not artInfo then
          return
      end
  
      local artConf = artConfigs:GetConfig(artInfo.artId)
  
      return artonf.artSide or 0
  end
  
  
  -- @MainGame.lua
  function MainGame:InitGlobal()
      -- (...)
      zzArtMgr = ArtifactCat()
      -- (...)
  end

  
  
  
• Example of Function Modded: (THIS works)
  

  -- root/../../ArtifactCat.lua
  function ArtifactCat.GetArtSide(self)
      local artInfo = zzArtMgr:GetArtInfo()
  
      if not artInfo then
          return
      end
  
      local artConf = artConfigs:GetConfig(artInfo.artId)
  
      return 1 --8686: artonf.artSide or 0
  end

  
  
• Attempted Alternative: (This Doesn’t Work)
  

  -- root/../../ArtifactCat.lua
  function ArtifactCat:GetArtSide(self)
      local artInfo = zzArtMgr:GetArtInfo()
  
      if not artInfo then
          return
      end
  
      local artConf = artConfigs:GetConfig(artInfo.artId)
  
      return 1 --8686: artonf.artSide or 0
  end

Key Point: Colon (:) vs. Dot (.):​

I want to better understand why using a colon (:) works, but a dot (.) doesn’t. Is it related to how the function is defined during MainGame:InitGlobal()? I’m curious about this difference and would like guidance on where to look to deepen my understanding.

---

2. Game B​

In this game, dumped files are already Lua-readable. I’m unsure of the Lua version used here. When I tried to inject a simple print("hello world"), it didn’t seem to produce any output. I suspect I’m missing a key detail or concept.

Intercepting GameMain:​

This game also has a GameMain.lua file that I intercept.
But nothing seems to work, so my questions are:

1. When code is injected during interception, is it added to the top or bottom of the file?
2. Can we replace the entire file during the luaL_loadbuffer scan?

---

Debugging​

For debugging, I use logcat to read print messages from the game’s process:

adb shell logcat -e Unity

(Filter messages with <tag>:s for example:

adb shell logcat -e Unity MIUIInput:s

MIUIInput:s

Other Debugging Techniques:​

1. When I dump game JSON data, I save it to a local file (debugDump.json).
2. On my PC, I run a script to repeatedly pull the file:
   

   adb pull /data/dLogs/debugDump.json

---

General Observations​

Initially, I used an emulator, but as the games and tools (e.g., Frida) updated, maintaining the setup became tedious. Testing became slower, so I switched to a rooted phone. However, I encountered errors—some related to frida-gadget.so files in the Python Frida folder (installed via pip).

• Temporary Fix: I created an empty file (it worked...) to replace the local frida-gadget.so, which resolved the issue.
  Running fridaserver, created a file named frida-gadget.so at same folder where i placed firaserver (arm64),
  and that behavior is something I don’t fully understand yet.
  File Location: \AppData\Local\Packages\PythonSoftwareFoundation.Python.3.12_qbz5n2kfra8p0\AC\INetCache\frida
  (sadly i can't get the error message I got at the time...)

---

That’s it for now.
Thank you for reading, and apologies for any language mistakes—English is not my native tongue.

 

[RedMundo]

Let me go straight to the point with my questions. However, feel free to share your experiences or the methods you used to "fix" similar issues.

I meant "i wish i could go straight to the point" sorry for this wall of text