U

Unknown virus - A new virus that is not registered in the anti-virus database. As a rule, Kaspersky Anti-Virus detects unknown viruses using the heuristic code analyzer and objects containing these viruses are flagged as possibly infected.
Updating the anti-virus database - A function of Kaspersky Anti-Virus that maintains the validity of the anti-virus protection of your computer. The updating process includes copying the anti-virus database from the Kaspersky Lab update servers to your computer and automatic integration of the database with Kaspersky Anti-Virus Personal.
Kaspersky Lab's update servers - A list of http- and ftp-servers updated regularly by Kaspersky Lab from which Kaspersky Anti-Virus copies the most recent version of the anti-virus database to your computer.