samueltulach / overlaycord

Simple proof of concept showing how you can abuse Discord's in-game internal module to draw on top of the game (even if the game is in fullscreen) from an external application without modifying any Discord files or loading its modules.

OverlayCord

This project is a simple proof of concept that shows you how to hijack Discord's internal game overlay from an external process without modifying any Discord files, loading any Discord modules, or hooking anything.

How does it work?

Discord's whitelisted internal module (DiscordHook64.dll), which is loaded by games using SetWindowHookEx, simply copies the framebuffer from a memory-mapped file. The code snippet from this repo is pretty much self-explanatory:

typedef struct _Header
{
	UINT Magic;
	UINT FrameCount;
	UINT NoClue;
	UINT Width;
	UINT Height;
	BYTE Buffer[1]; // B8G8R8A8
} Header;

bool ConnectToProcess(ConnectedProcessInfo& processInfo)
{
	std::string mappedFilename = "DiscordOverlay_Framebuffer_Memory_" + std::to_string(processInfo.ProcessId);
	processInfo.File = OpenFileMappingA(FILE_MAP_ALL_ACCESS, false, mappedFilename.c_str());
	if (!processInfo.File || processInfo.File == INVALID_HANDLE_VALUE)
		return false;

	processInfo.MappedAddress = static_cast<Header*>(MapViewOfFile(processInfo.File, FILE_MAP_ALL_ACCESS, 0, 0, 0));
	return processInfo.MappedAddress;
}

Please note that this straightforward example uses very basic CPU rendering, which does not offer optimal performance. In addition, regardless of your intention to use GPU rendering (such as DirectX), the framebuffer will still be copied by the CPU.

Media

Video showing the example (in case embed does not work click here)

Image showing the example

Image showing custom project that renders using DX11

Image showing custom project rendering over anticheat protected game

overlaycord's Issues

ImGui example code clarifications

Nice work on this project. I'm pretty new to DirectX and need a bit of help. Your ImGui example code is helpful, but there are some missing pieces that I cannot figure out.

CreateDeviceD3D() is incomplete, but it looks like all that's left to do is actually create the device and assign to a global variable.

SendBuffer() is where I'm having issues. When copying data from one buffer to the other, you have:

memcpy(mainHeader->ActualBuffer, mappedResource.pData, bufferSize);

mainHeader is not defined anywhere and I'm not sure what this object is. Also, at what point would the call be made to SendBuffer()? Would this be in place of the SendFrame()?

I'm trying to modify your code to get a simple ImGui::ShowDemoWindow() to display. Any help is greatly appreciated.

ImGui

I dont really understand how i could add imgui to that, can someone help me pls