How to find Lua C function addresses in roblox?

jpmorgan1234

Posts: 5

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Joined: Jan, 2021

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Posted

Hello, I'm back with another question.

I spent the past few days reading all about Lua script executors, Lua C documentation, and how it all works. I need to find functions, especially Lua_Load and Lua_Pcall in roblox, but I can't seem to get a reference.

I have found pushglobaltable, and setfield, but those are useless to me at the moment.

What I have tried:

- cross reference strings from Lua source code, v5.2

- compile lua and build sigs for vanilla lua engine and use them to search for roblox lua C code.

Those two methods are completely ineffective because they have removed/encrypted all the strings in lua source, and they have made heavy modifications & obfuscated important functions.

If anyone has any idea on what to look for next to find Lua_pcall & Lua_load I would greatly appreciate it.

Thanks in advance

EDIT:

Good news, I have found LuaL_setfuncs after hours of matching sigs. I'll work my way through from here.

Edit 2:

Everything else seems to be heavily modified/obfuscated, I can't build reliable sigs. If anyone has experience reversing their Lua engine please give me some direction in finding pcall & the deserializer (lua_load)

Added

@_realnickk

Thank you very much, can you tell me how you got to those string xrefs? How long did it take?

Added

@_realnickk

No, that's not what I meant, I meant how you got to those string xrefs in the first place. If you reversed roblox starting from scratch and IF didn't know any of those strings, how did you figure it out?

Anyways, I am on fire today, I found 5+ lua funcs this morning. Lmk if anyone needs them. I might do some more reversing.

What I have found so far

+ luaL_findtablex

Thanks for the strings anyways, it saves me a ton of time.