Computer viruses are malicious software programs that can damage computers by deleting files, displaying unwanted messages, or slowing down systems. Viruses spread by attaching themselves to other programs or files and transferring to other computers through networks, email attachments, removable drives, or downloaded files from the internet. While some are created for research or art, most are made to damage systems or steal personal information. Antivirus software detects viruses by scanning files and memory against a database of known virus signatures or monitoring for common virus behaviors. It is important to keep antivirus software up to date, avoid opening suspicious email attachments, only download files from trusted sources, and backup files regularly to prevent virus infections and data loss.

1. Computer Virus ArnabSingha, VI CSE VipinBorkar, VI CSE 1

2. What is a Computer Virus A kind of software programs produced by unknown people and harmful to the computers Some varieties of these software are the Viruses, WormsandTrojan horses 2

3. What is a Computer Virus The term “Virus" is often used in common to describe all kinds of malware (malicious software) 3

4. Damages done by Viruses Sometimes display unwanted messages Some tend to destroy programs or data Clog computer memory and hence sometimes result in system crashes Format hard disks, Damage programs, Delete files 4 Viruses

5. Damages done by Viruses Simply replicate themselves Presents text, video, or audio messages making the user know their presence Bug-ridden, and these bugs may lead to system crashes and data loss 5

6. Virus spreading methods A viruses can copy itself and infect a computer without permission or knowledge of the user attaches itself to other software programs or data files 6

7. Virus spreading methods Spreads from computer to computer when the host is taken to the uninfected computer over a network such as over the Internet or carrying it on a removable medium - a floppy disk, CD, or USB drive 7

8. Virus spreading methods Many viruses are existed in the Internet today and new ones are discovered every day. spread via downloaded software and data files, and email attachments, etc 8

9. Virus spreading methods Some old viruses are installed themselves into the disk boot sector runs when the user boot the computer from the disk 9

10. Virus spreading methods Some viruses spread through instant messaging A virus, in an infected machine, may send a web-address-link as a message to other contacting machines Thinking the link is from a friend (a trusted source), the recipient may sometimes follow the link to the websit. 10

11. How Viruses are born Unlike biological viruses, computer viruses do not simply evolve by themselves deliberately created by programmers, or by people who use virus creation software 11

12. How Viruses are borne Viruses are written as research projects, pranks, vandalism, to attack the products of specific companies, to distribute political messages, and financial gain from identity theft, spyware, and cryptoviral extortion. 12

13. How Viruses are borne Some virus writers consider their creations to be works of art See virus writing as a creative hobby 13 Releasing computer viruses is a crime in most jurisdictions

14. Viruses can avoid detection To avoid detection by users, viruses employ different deception methods They do not make themselves to change the date of last modified increase file sizes damage the files 14

15. Viruses can avoid detection They kill the tasks associated with antivirus software before it can detect them 15

16. How Antivirus software works? Detect using a list of virus signature definitions comparing the files stored on fixed or removable drives (hard drives, floppy drives), against a database of known virus "signatures". 16

17. How Antivirus software works? Use a heuristic algorithm to find viruses based on common behaviors Examin the content heuristics of the computer's memory (its RAM, and boot sectors) 17

18. How Antivirus software works? Some anti-virus programs gives you a real time protection Examin files as they are being opened, downloaded, copied, accessed, and transmitted etc 18

19. How Antivirus software works? They need regular updates in order to gain knowledge about the latest threats 19

20. Damage prevention & data recovering Take regular backups (including OS) on different media, unconnected to the system (most of the time) 20 How to prevent damages caused by viruses?

21. Damage prevention & data recovering Use backups on optical media like CD and DVD (read-only), as they can no longer be affected by viruses. Use an OS on a bootable, to start the computer if the installed OS become unusable. 21 How to prevent damages caused by viruses?

22. Keep your computer Virus free Install reliable anti-virus software the most important step you can take towards keeping your computer clean of viruses Update your anti-virus software regularly variations of viruses and new ones can be slipped if your software is not current 22

23. Keep your computer Virus free Get immediate protection Configure your anti-virus software to boot automatically on start-up and run at all times 23

25. ensure that you examine and scan email and other attachments before they run as they might contain viruses

26. Scan all incoming email attachments

27. Do not open any email attached files if the subject line is questionable, unexpected or the source (address) is unknown, suspicious or untrustworthy 24

28. Keep your computer Virus free Delete chain emails and junk email Do not forward or reply to any of them, they clogs up the network Some viruses can replicate themselves and spread through email as a chain 25

29. Keep your computer Virus free Be careful when downloading files from the Internet Ensure that the source is a legitimate and reputable one save all downloads to one folder and test them with your own anti-virus software before use 26

30. Keep your computer Virus free Always scan new files for viruses before you use them 27

31. Keep your computer Virus free Backup your files on a regular basis 28

32. Keep your computer Virus free If your computer is on a network, make sure you have security steps in place to prevent unauthorized users putting files on your computer 29

33. Keep your computer Virus free Take care using USB flash cards, CDs, zip and floppy disks The more computers flash cards, CDs, zip cards and floppies have been used on, the better the chance of a virus infecting them – clean them before use 30

34. THANK YOU 31