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Macro Viruses

These viruses use another application's macro programming language to distribute themselves.
They infect documents, such as Microsoft Word or Excel and cause a sequence of actions to be
performed automatically when the application is started. Macro viruses spread rapidly, as users
share infected documents such as e-mail attachments, disc networks, modems and the Internet.
Examples of macro viruses are Melissa, Word Concept, etc.

Extra Bytes
Melissa Virus was released on 26 March, 1999 and was designed to infect macros in
documents used by MS Word 97 and 2000. It propagated by e-mailing itself to the first fifty
addresses in the address book of MS Outlook (the e-mail program that is a part of MS Office).

Malware

Malware is made up of two words malicious and software. It is a software that enters into a
computer and damages it without the knowledge of the user. Malware is a trouble-causing
program. It may be a virus, worm, Trojan horse or spyware. Malware not only interrupts the
normal working of a computer, but also steals important information.

Worms

A computer network is formed when two or more computers are connected to one another. A
Worm is a kind of malware that uses computer networks to send copies of itself to other
computers on the network. A virus requires human action such as transferring the infected file to
spread itself, but a worm can spread without any human intervention. It replicates without the

knowledge of the user. Worms can cause severe harm to the network such as blocking the network
and reducing its speed.

Trojan Horse

Trojan horse or Trojan, is a kind of malware that appears to be useful software but will actually
cause damage once installed or executed on your computer. After getting installed, it allows
unauthorised access to the computer. They are very dangerous as they allow your computer to be
remotely controlled by someone else and may lead to loss of personal and confidential
Information.

Worms and Trojan horses, like viruses, may harm the data or affect the performance and the speed
of a computer.

Spyware

Spyware refers to computer programs that secretly gather information about the user and relay it
to advertisers or other interested parties. They are also called spybots or tracking software.
Spyware is often installed without the user's consent when:

• The user downloads something from the Internet.

• The user clicks on something in a popup window that appears while browsing.

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