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Program Virus

A Program Virus infects programs installed on a computer. Program files
usually have extensions such as .exe, .com, .sys, .bat, .dll, .bin, and .pif.
When the infected program is executed, the virus becomes active in the
memory, making copies of itself and infecting all files accessed by the
infected program. Sunday, Cascade, Acid Rain, and Amoeba. A are some
examples of program viruses.
Macro Virus
A Macro is a set of instructions used to automate tasks that
are performed more often, such as creating or deleting files, or
modifying the contents of existing files. A Macro Virus infects
macros written for software such as Microsoft Word, Excel, and

PowerPoint. Melissa, Relax, Concept, and Nuclear are some
examples of macro viruses.
Multipartite Virus

A Multipartite Virus infects a computer and spreads in multiple ways. It attacks both the boot sector
and the program files. Ghostball, Tequila, and Invader are some examples of multipartite viruses.

Polymorphic Virus
A Polymorphic Virus is a virus designed to avoid detection by antivirus software.
It changes its program code every time it replicates and infects a new file.
Marburg, Tuareg, and Satan Bug are some examples of polymorphic viruses.

Stealth Virus
A Stealth Virus is capable of hiding itself inside data files. It is able to
deliberately avoid detection by antivirus software. Frodo, Joshi, and
Whale are some examples of stealth viruses.

Worm

A Worm is malware that stays inside the memory of computer and
replicates itself automatically to other computers through computer
networks without any human interaction. Unlike a virus, a worm
usually does not cause damage to programs or data in a computer
but consumes too much system memory or network bandwidth,
causing servers and individual computers to stop responding. Morris,
Mydoom, and I LOVEYOU are some examples of computer worms.

Trojan Horse
A Trojan Horse is a program that hides its destructive intentions by disguising itself
as a game, useful application, or utility. It is usually distributed as email attachments
with tempting names and descriptions that prompt a user to open them. It can
delete files from a disk, send your personal information, such as passwords, or give
remote access to your computer to cyber-thieves and hackers. Beast, DarkComet ,and
Zeus are some examples of Trojan Horses.

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