Handle leak allows debugger detection

[mrexodia]

Fix in x64dbg: x64dbg/x64dbg#3234

Reproduction code (you need to run it on an x64dbg with the fix above, otherwise it triggers anyway):

#include <Windows.h>
#include <cstdio>
#include <cinttypes>

int main()
{
    puts("");

    wchar_t executablePath[MAX_PATH] = L"";
    GetModuleFileNameW(0, executablePath, _countof(executablePath));

    auto hNtdll = CreateFileW(L"C:\\Windows\\system32\\ntdll.dll", GENERIC_READ, 0, nullptr, OPEN_EXISTING, 0, nullptr);
    printf("[AntiDebugHandle] ntdll: 0x%zX (LastError: %u)\n", (uintptr_t)hNtdll, GetLastError());

    auto hExe = CreateFileW(executablePath, GENERIC_READ, 0, nullptr, OPEN_EXISTING, 0, nullptr);
    printf("[AntiDebugHandle] exe: 0x%zX (LastError: %u)\n", (uintptr_t)hExe, GetLastError());
    
    puts("");
}

You would probably need to create a fake QIODevice (or whatever is the abstract of QFile) and use a file mapping backend. Once you have the section mapping open you can close the file handle and things will work fine.

[horsicq]

Thanks! I will take a look.