Code Injection

[jay lee]

In Cheatengine I can use a code injection template to change a function in a running process, how can I do that in ahk?

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[lmstearn]

Replacing a function might be possible - it involves detour and trampoline functions - @malcev includes that in this example at
MinHook - API Hooking Library.
Related, see WriteProcessMemory Not working, AhkHook: API hooking with AutoHotkey and Memory Process reading/Writing & Pattern Scans (Array of bytes).

[jay lee]

I found out how to do it!

Code: Select all

replace_instruction(hProcess, address, new_opcode) {
    new_opcode := StrSplit(new_opcode, " ")
    for index, hex_value in new_opcode
        new_opcode[index] := "0x" . hex_value
    
    VarSetCapacity(opcode, new_opcode.MaxIndex(), 0)
    Loop % new_opcode.MaxIndex()
        NumPut(new_opcode[A_Index], opcode, A_Index - 1, "UChar")
    
    if !DllCall("WriteProcessMemory", "Ptr", hProcess, "Ptr", address, "Ptr", &opcode, "UInt", new_opcode.MaxIndex(), "Ptr", 0) {
        MsgBox, Failed to replace instruction.
        return
    }
    return
}

but I dont know how to convert ASM to hex as I mentioned in my newest post

[lmstearn]

The ASM code has to be assembled to machine code, would the Auto Assembler help there? Check types for 64 bit if compiling for that. It all then has to go into a custom DLL, see here, and here for the mcode bit.