EvilZone

Programming and Scripting => C - C++ => : bubzuru October 03, 2012, 12:21:19 AM

: (Snippit) How To Make a Dll Unload Its Self
: bubzuru October 03, 2012, 12:21:19 AM

i was looking for code to make a dll unload itself, and foud some broken code
problem was the coder was pushing a handle to the exe not the dll

here is the fixed code 

: (c)

void UnloadSelf(HMODULE hdl)
{
   LPVOID FP_ExitThread = (LPVOID)GetProcAddress(GetModuleHandle("kernel32.dll"), "ExitThread");
   __asm
   {
      push hdl
      push FP_ExitThread
      jmp dword ptr [FreeLibrary]
   }
}

to get the handle to the loaded dll you can just grab it from main

example:

: (c)

BOOL WINAPI DllMain(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpvReserved)
{
    switch (fdwReason)
    {
        case DLL_PROCESS_ATTACH:
            MessageBox(0,"hello","world",0);
            UnloadSelf(hinstDLL);
            break;
        case DLL_PROCESS_DETACH:
        case DLL_THREAD_ATTACH:
        case DLL_THREAD_DETACH:
            break;
    }
    return TRUE;
}

beats injecting code to call FreeLibrary

: Re: (Snippit) How To Make a Dll Unload Its Self
: Satan911 October 03, 2012, 07:22:42 AM

Why can't the WinAPI be more simple..

: Re: (Snippit) How To Make a Dll Unload Its Self
: Xires October 03, 2012, 07:39:09 PM

Because it's WinAPI?  Have a look at intermixing MFC with custom WinAPI class wrappers for use w/ DirectX.  It's atrocious.  Oh, how simple & elegant is the world of FOSS.

: Re: (Snippit) How To Make a Dll Unload Its Self
: TETYYS April 26, 2013, 08:33:11 PM

Sorry for reviving thread, but this method causes application to crash, or unlass FileZilla to crash. I used this and it worked.

: (C++)

EXTERN_C IMAGE_DOS_HEADER __ImageBase;
CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)FreeLibrary, &__ImageBase, 0, NULL);


: Re: (Snippit) How To Make a Dll Unload Its Self
: Xires April 28, 2013, 07:06:57 PM

No need to feel sorry when adding important/useful information.