COMPUTER VIRUSES Presented by BSCSI Maheen Zofishan Saba

COMPUTER VIRUSES …. ! Presented by: BSCS-I Maheen Zofishan Saba Naz Numan Sheikh Javaria Munawar Aisha Fatima.

SICK OF COMPUTER VIRUSES? What they are… Where they come from… Why they are here…

Index 1. Concept 2. History 3. Symptoms 4. Types Of Viruses 5. Anti-Virus 6. Conclusion

What is a Computer Virus? • A Computer Virus is a program that can copy itself and infect a computer without the permission or knowledge of the user.

A Computer Virus has 2 major characteristics: The ability to replicate itself, and the ability to attach itself to another computer file. . .

History • 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 Elk Cloner, and was the first computer virus to appear outside the computer where it was created in.

How Virus Spread: A piece of software contain virus (Host Program) Someone share the program(E-Mail , Floppy disk , CD) Virus Will copied to that computer. The Software in computer will Infected.

SYMPTOMS The following are a few Symptoms that your 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.

Difference b/w Virus & worm Virus The virus may exist on your computer but it actually cannot infect your computer unless you run or open the malicious program. It is important to note that a virus cannot be spread without a human action, (such as running an infected program) to keep it going. worm A worm is similar to a virus by design and is considered to be a sub-class of a virus. Worms spread from computer to computer, but unlike a virus, it has the capability to travel without any human action. A worm takes advantage of file or information transport features on your system, which is what allows it to travel unaided.

Virus Trojan Horse Time Bomb Boot Sector Macro Logical Bomb Worm E-Mail Script Virus

Trojan Horse is a destructive program. It usually pretends as computer games or application software. If executed, computer system will be damaged.

A time bomb is a virus program that performs an activity on a particular date.

Logical Bomb: is a destructive program that performs an activity when a certain action has occurred. A logical bomb

Worm Virus: A worm is also a destructive program that fills a computer system with self-replicating information, clogging the system so that its operations are slowed down or stopped.

Macro Virus A Macro Virus is associated with application software like word and excel. When opening the infected document, macro virus is loaded into main memory and destroys the data stored in hard disk. This type of viruses can easily spread through E-mail, when users unknowingly exchange infected documents.

Commonly found script viruses are written using the Visual Basic Scripting edition (VBS) and the Java. Script programming languages.

E-Mail Virus Activated when recipient opens the e-mail attachment Activated by open an e-mail that contains the virus Uses Visual Basic scripting language

File Infector Virus A file infector is a virus that infects an executable file. Typically affects only one type of file.

Macro Virus • These type of virus infects word , excel, Power. Point, access and other data files. Once infected repairing of these files is very much difficult.

WEB SCRIPTING VIRUS There are few website that execute complex code with the purpose to provide interesting content , these codes often get exploited and due to this a virus becomes able to infect a machine and to take actions on a machine via website. This particular virus is called web scripting virus.

Browser Hijacker Alters the search and error page of a browser and redirects the user to its own page.

Boot Sector Virus It places its own codes and commands into MBR.

An antivirus software is a computer program that identify and remove computer viruses, and other malicious software like Worms and Trojans from an infected computer.

Anti-Virus NOD 32 Mc. AFee Antivirus AVG AVAST Bit-Defender

The Anti-Virus Program Checks Each Files In the Computer. This program detects virus containing file and Block it’s working and also Delete it permanently…

…Anti-Virus Program also gave the facility for online virus blocking. The infected Files that are download through internet can be detected and easily removed.

Always update your anti- virus software at least weekly. Back up your important files and ensure that they n be restored. Change the computer's boot sequence to always start the PC from its hard drive.

Conclusio For better and safe ncomputation anti-virus software should be installed and be helpful for global network system freely.

Any Question …. N 0. . .