User manual

Viruses and more
A computer virus is a program that is capable
to attach itself to other programs after
being executed and cause an infection. Viruses multiply themselves unlike logic bombs
and Trojans. In contrast to a worm, a virus always requires a program as host, where the
virus deposits his virulent code. The program execution of the host itself is not changed
as a rule.
Rootkit
A rootkit is a collection of software tools that are installed after a computer system has
been infiltrated to conceal logins of the infiltrator, hide processes and record data -
generally speaking: to make themselves invisible. They attempt to update already
installed spy programs and reinstall deleted spyware.
Script viruses and worms
Such viruses are extremely easy to program and they can spread - if the required
technology is on hand - within a few hours via email round the globe.
Script viruses and worms use one of the script languages, such as Javascript, VBScript
etc., to insert themselves in other, new scripts or to spread themselves by calling
operating system functions. This frequently happens via email or through the exchange
of files (documents).
A worm is a program that multiplies itself but that does not infect the host. Worms can
consequently not form part of other program sequences. Worms are often the only
possibility to infiltrate any kind of damaging programs on systems with restrictive
security measures.
Spyware
Spyware are so-called spy programs that intercept or take partial control of a computer's
operation without the user's informed consent. Spyware is designed to exploit infected
computers for commercial gain.
Trojan horses (short Trojans)
Trojans are pretty common nowadays. We are talking about programs that pretend to
have a particular function, but that show their real image after execution and carry out a
different function that, in most cases, is destructive. Trojan horses cannot multiply
themselves, which differentiates them from viruses and worms. Most of them have an
interesting name (SEX.EXE or STARTME.EXE) with the intention to induce the user to
start the Trojan. Immediately after execution they become active and can, for example,
format the hard disk. A dropper is a special form of Trojan that 'drops' viruses, i.e.
embeds viruses on the computer system.
Zombie
A Zombie-PC is a computer that is infected with malware programs and enables hackers
to abuse computers via remote control for criminal purposes. On command, the affected
PC starts denial-of-service (DoS) attacks, for example, or sends spam and phishing
emails.
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