Malicious code published recently allows hackers to attack on upcoming Windows Vista (Code name Longhorn). The code targets new command line shell named as MONAD or MSH. Monad is replacement of command line shell which can be seen in current version of windows. Command line shell allows users to interact with computer in textual commands. Monad is supposed to be more powerful than UNIX shells. Monad is capable of running more complex quarries from either keyboard or scripts. Microsoft planns to ship monad in Windows Vista enabled by default , this could make outbarke of attacks on Windows Vista. However Microsoft’s efforts can be exploited to make more and more viruses based on MSH scripts.