title: Hijacking DLL File
body: <p>I am trying to learn about DLL Hijacking.
  If I were to create a DLL file that contains two functions; add and subtract, say this was called mathematics.dll.
  Now I create a program that loads mathematics.dll, so that I can add &amp; subtract.</p>
  
  <p>Then I hijack the original dll file with my new DLL file which can multiply and divide, but I must also implement the two original functions of the hijacked DLL which are for whatever reason unknown.. How can I pass calls through the original DLL so that the program can still load the original DLL file.</p>
  
  <p>And even then how can I inject hooks into my code so that I can use my newly found multiply and divide functions?</p>
  
  <p>If all of this is nonsense and I'm trying to pursue this wrong, please shed light on this subject, as I'm not so familiar with it.</p>