Stealth
Any means of hiding activities and covering tracks
Stealth techniques are widely used in malware to conceal the malicious program's activities from victims both as they occur and in retrospect.
Rootkit methods are common in many malware strains, preventing the user from discovering that their system has been infected. Drive-by downloads use stealth to install malware silently without the user's knowledge. Some malware may even remove itself once its task has been completed and attempt to remove any record of its presence.
Stealth varies in complexity from simply using common filenames or the 'hidden' attribute, to disabling useful functions required to monitor the system, to full kernel or even lower-level rootkits.