WIKIRoot kit
A root kit is a software package that allows a malicious computer hacker to secretly retain access to and control of another person's computer.
When a computer is broken into (i.e. some kind of unauthorised remote access to it is gained), the hacker involved needs to do two things:
1. Cover their tracks in some way - not simply so no-one can tell who they are, but ideally so that no-one can even tell that the computer was broken into.
2. Ensure that they will be able to re-access the computer safely, and at their leisure, at some future time.
The root kit itself does not help the hacker gain initial access to the computer. The real life metaphor would be a burglar who after breaking in through a window, replaces the glass, wipes his finger prints off, tidies up nicely, and then takes a copy of your door key. He can now let himself in easily at any future date.
A root kit is so called because a username of 'root' is traditionally the most powerful user on a Unix system - the one that can do whatever they want to the computer. A root kit therefore provides a secret means for the malicious hacker to become the 'root' user on the targeted computer at will.
See also: