Abstract: The message flow of Windows operating system was introduced and the potential threats was analyzed. A solution based on hardware-assisted virtualization was developed to defend against the software key logger. A virtual machine monitor was implemented using Intel virtual technology. When the protected thread is reading keyboard input, the keyboard interrupt is handled in the virtual machine monitor. By reading scan code of the keyboard in the virtual machine monitor, the keyboard input can be safely sent to the protected thread.

Key words: Anti-key logger, Hardwarcassisted virtualization,Interrupt, Virtual machine monitor