A programme that fraudulently gains or maintains administrator level access that may also execute in a manner that prevents detection. Once a programme has gained access, it can be used to monitor traffic and keystrokes; create a backdoor into the system for the hacker's use; alter log files; attack other machines on the network; and alter existing system tools to circumvent detection. Rootkit commands replace original system command to run malicious commands chosen by the attacker and to hide the presence of the Rootkit.