Page 19 - Computer Class 05

8 Slower computing speed 8 Abnormal computer behaviour

8 Unexplained data loss 8 Frequent computer crashes

Computer virus didn’t really exist until the mid 1980s. The first computer viruses were
created in University labs to demonstrate how much of a threat the vicious code could

be.

How the Viruses Enter the Computer?

A virus can only spread from one computer to another when its host is taken to
the uninfected computer, for instance by a user sending it over a network or the

internet or by carrying it on a removable medium, such as a floppy disk, CD or
USB drive.

Some other ways are given below:
8 Bluetooth mobile devices
8 Opening spam-mail attachments

8 Internet software, gaming and multimedia downloads
8 Accepting to open without scanning devices, USB devices, CD, DVD

Viruses behave in different ways. Some viruses stay active only when the
application or a part of it is running. Turn the computer OFF and the virus is

inactive. Other viruses will operate every time we turn ON our computer after
infecting a system file or network.

Types of Viruses

There are many types of viruses. Let us read about them.

Boot Sector : This type of virus can take control when you start or boot
your computer. One way it can spread is by plugging an

infected USB drive into your computer.

Worms : A worm is technically not a virus, but a program very similar
to a virus that has the ability to self-replicate and can lead

to negative effects on the system and most importantly they
are detected and eliminated by antivirus. For example:

Mapson, Sobig.D, Trile.C.

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