This is a demo of Import address table hooking tested with Notepad.

So basically this program (is being) designed to hook the function called CreateFileW() imported from KERNEL32.dll or an equivalent to inject and perform my own code which doesn't relate to the original functionallity.

Quoted from: Microsoft Docs

HANDLE CreateFileW(
  LPCWSTR               lpFileName,
  DWORD                 dwDesiredAccess,
  DWORD                 dwShareMode,
  LPSECURITY_ATTRIBUTES lpSecurityAttributes,
  DWORD                 dwCreationDisposition,
  DWORD                 dwFlagsAndAttributes,
  HANDLE                hTemplateFile
);

Build this project. Open notepad.exe and inject the generated dll and click "save as...". And BOOOM! A messagebox saying "CreateFileW function has been hooked" pops up!

Needless to say anything other than messagebox would work if you code so.

Because why not? Hooking is beautiful.