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Gowri: Different Threats to computer are:
1. Virus: Computer viruses are nothing but computer programs that do unwanted things with
your computer resources. For example, you are working on PC and you are repeatedly receiving
annoying message.
2. Worms: Worms are self-replicating viruses and consume the system
resources.
3. Trojan Horse: A Trojan horse is simply a computer program. It is like
a program that claims to be a reliable program such as being a game but
instead causes damage when you run it like it may erase your hard disk.
Trojan horses do not replicate automatically.
4. Spyware: Spyware is a software program that secretly gathers personal
information and sends it without the user's knowledge while the computer
is online.
5. Phishing: Phishing is an attempt to acquire sensitive information such as
username, password or credit card details.
6. Pharming: Pharming is an attack in which a hacker attempts to redirect a website’s traffic to
another fake website.

Aryan: How can I know if my computer has a virus?

Gowri: There are some symptoms of computer virus.
Symptoms of a Computer Virus

The computer
crashes and then
The computer restarts
runs slower than frequently.
usual. Applications on the
computer do not
work correctly.

Disks & disk
drives are
inaccessible.

New icons or
shortcuts will appear
on the screen or disk
You see drives.
unusual error
messages. Antivirus programs
cannot be installed on
the computer or antivirus
will not work.

Fig. 7.1

Computer Security 71