Antivirus software identifies and removes malware like viruses, spyware, and Trojans. Malware is undesired software that infiltrates systems without consent. Viruses are self-replicating programs that alter computer operations secretly. They are sometimes created as art, research, pranks, or to target specific companies. Antivirus programs scan files against virus definitions and monitor behavior to identify infections, using static scanning of files or dynamic real-time scanning as new files are opened. Popular free antivirus software includes Avast.

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Introduction
 Antivirus software consists of computer
programs that attempt to identify, thwart and
eliminate computer viruses and other malicious
software (malware).
 Malware or Malicious Software is software
designed to infiltrate or damage a computer
system without the owner's informed consent.
 Types of malware include spyware, adware,
Trojan horses, Worms, and viruses.

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Malware
“Know your enemy”

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The Virus
 A computer virus is a self-replicating computer
program written to alter the way a computer
operates, without the permission or knowledge
of the user
 Why people create computer viruses?
 Some virus writers consider their creations to be
works of art, and see virus writing as a creative hobby
 Viruses have been written as research projects,
pranks, vandalism, to attack the products of specific
companies

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The Virus
 Why people create computer viruses?
Some viruses were intended as "good
viruses". They spread improvements to the
programs they infect, or delete other viruses.
These viruses are, however, quite rare, still
consume system resources, may accidentally
damage systems they infect.

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Antivirus SW

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Antivirus
 Antivirus software typically uses two different
techniques to accomplish his mission:
 Examining (scanning) files to look for known viruses
matching definitions in a virus dictionary
 Identifying suspicious behavior from any computer
program which might indicate infection. Such analysis
may include data captures, port monitoring and other
methods.

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Antivirus modes
 Anti-virus programs have two basic modes:
 “static” file scanning: useful for when you have to
scan a file or a volume to check to see if any of the
files are currently infected with malware
 real-time “dynamic” scanning: is really what is needed
to prevent the computer from getting infected in the
first place. In this mode, all files that the operating
system opens or uses are scanned first before they
are fully opened.

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Antivirus Example
 one of the most popular full-featured
freeware anti-virus applications for
Microsoft Windows users.
 Official website: http://www.avast.com/

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