hardcoded address in disassembly

Question

I'm writing optimized Windows based shellcode in C++ and I have problem avoiding hardcoded addresses in C++ while passing it to function.

e.g:

My_CreateThread(NULL, NULL, (LPTHREAD_START_ROUTINE)&thread_callback, NULL, NULL, NULL);

DWORD WINAPI thread_callback(LPVOID lpParam)
{
    // stuff..
}

in disassembly, it shows CreateThread(..., cardcoded_address, ..); instead, I want to pass this address like "from this location to thread_callback"

is there any way to avoid it? (because shellcode should be address independent?)

Regards.

Answer 1

Anyways, I was searching/doing some stuff and the final thing I've could done is that you can solve this with delta offset.

Explanation: at the very first function of your code, there should be function like this:

DWORD delta;

__asm {
    call GetBasePointer
    GetBasePointer:
    pop eax
    sub eax, GetBasePointer
    mov [delta], eax
}

You can also google for delta offset for more details. Afterwards, you can do something like this:

My_CreateThread(NULL, NULL, (LPTHREAD_START_ROUTINE)((DWORD)thread_callback + (DWORD)delta), NULL, NULL, NULL);

DWORD WINAPI thread_callback(LPVOID lpParam)
{
    // stuff..
}

and it will work fine,

Regards.