NTRootkit is a Trojan that can hide certain files, processes or entries of the Windows Registry and also log the keystrokes typed by the user, which can be used to capture passwords or other kind of sensitive information. This would pose a threat to the user's confidentiality.
NTRootkit does not spread automatically using its own means. It needs an attacking user's intervention in order to reach the affected computer. The means of transmission used include, among others, floppy disks, CD-ROMs, email messages with attached files, Internet downloads, FTP, IRC channels, peer-to-peer (P2P) file sharing networks, etc.
NTRootkit only works on machines with the operating systems Windows NT, 2000 or XP installed, as a service must be loaded for this program to run. The effects of NTRootkit vary, as there are different versions of this tool that carry out different actions.