A computer virus is a malicious program that can replicate itself and spread from computer to computer without permission. It can slow down or damage infected systems. The first computer virus, called "Creeper," was created in 1971. Later viruses caused more harm by deleting files or collecting users' personal data. To avoid viruses, users should only download files from trusted sources, use antivirus software, keep systems updated, and be wary of email attachments from unknown senders. Other malware like spyware and Trojans also pose threats by monitoring users' activities or gaining control of infected devices without consent.

1. COMPUTER VIRUS
SUBMITTED BY,
ABINIYA.K.VIJAYAN
ROLL NO : 22
PHYSICAL SCIENCE

2. COMPUTER VIRUS
 A computer virus or computer worm is a malicious software program that can
self-replicate on computers or via computer networks – without the user being
aware that his machine has become infected.
 Because each subsequent copy of the virus can also self – replicate, infections
can spread very easily.
 All computer viruses are man made. They are loaded onto the computer
without the users knowledge and runs against his wishes. A simple virus that
can make a copy of itself over and over again is relatively easy to produce.
 Even such a simple virus is dangerous because it will quickly use all available
memory and bring the system to a halt.

3.  The first computer virus was called “Creeper”. It was invented in the early
1970’s. Since then, millions of viruses have been invented.
 The first known computer virus was written in 1981 by a man named Rich
Skrenta. This virus was termed as “Elk Cloner”.
 According to Webster’s Collegiate Dictionary, a computer virus is “a computer
program usually hidden within another program that produces copies of itself
and inserts them into other programs or files, and they usually perform a
malicious action (such as destroying data)”.

4. How does virus affect
 By downloading files from the Internet.
 Sharing music, files, or photos with other users.
 Through pen drive.
 Through e-mail attachments or spam e-mails.
 Through unprotected or poor administrator passwords.
 Visiting an infected website.
 Downloading free games, toolbars, media’s.
 Installing mainstream software applications without thoroughly reading
license agreements.

5. What are the symptoms that computer
might have a virus?
 Slow response and slow program execution.
 Random hard drive crashes and restarts.
 Distorted graphics and text.
 Files that have mysteriously vanished
 Extensive pop-up ads.
 Inability to open files with existing passwords.

6. Impact of Virus
 Disrupts the normal functionality of respective computer system.
 Disrupts system network use.
 Modifies configuration setting of the system.
 Disrupts computer network resources.
 Destructs of confidential data.
 Slow computer performance.
 Erratic computer behaviour.
 Unexplained data loss.
 Frequent computer crashes.

7. MALWARE
 “Malware” is short for malicious software.
 It is a type of software that could harm a computer system, interfere with
and gather a user’s data, or make the computer perform actions without the
owner’s knowledge or permission.
 “Malware” is the general term covering all the different types of threats to
your computer safety such as viruses, spyware, worms, trojans, rootkits etc.
 Malware is often used to against individuals to gain information such a
personal identification numbers or details, bank or credit card numbers and
passwords.

8. SPYWARE
 It is a type of malware.
 Spyware is a program that gets installed without the user’s permission.
 Spyware monitor’s the user’s activities on the internet and transmits that
information to the third party.
 It is often hidden from the user.
 On the internet it is sometimes called a spybot Or tracking software.
 Spyware is mostly used for the purposes of tracking and storing internet users
movements on the web.

9. How to avoid spywarer
 Read licensing agreements.
 Watch out for anti – spyware scams.
 Beware of clickable ads.
 Keep your Internet browser up to date.
 Scan your computer often.
 Be selective about what you download to your computer.

10. Trojan
 A Trojan or Trojan horse, in computing is any malicious computer program which
misrepresents itself as useful, routine or interesting in order to persuade a victim
to install it. The malicious activities that they perform are the following ;
 Deleting data
 Blocking data
 Modifying data
 Copying data
 Disrupting the performance of computers or computer networks.

11.  Unlike computer viruses and worms, Trojans are not able to self-replicate.
 Trojans are usually used to take complete control of the computer.
 According to the type of action that they can perform on the affected computer,
they are classified as follows :
 Rootkit : To prevent malicious programs being detected.
 Trojan-Downloader : It can download and install new versions of malicious
programs onto your computer.
 Trojan- Game thief : It steals user account information from online gamers.

12.  Trojan-Spy : It can spy on how the user is using the computer.
 Trojan-Mailfinder : It can harvest email addresses from your computer.

13. Ways to overcome
 Use antivirus protection and a firewall.
 Get antispyware software.
 Always keep your antivirus protection and antispyware software up-to-date.
 Update your operating system regularly.
 Increase your browser security settings.
 Avoid questionable websites.
 Only download software from sites you trust.
 Carefully evaluate free software and file-sharing applications before downloading
them.
 Don’t open messages from unknown senders.
 Immediately delete messages you suspect to be spam.

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