Virus
Illegal self-replicating small program that destroys data and applications programs. OR, Illegal self-replicating small program that disturbs normal functioning of a computer in many ways.
-In 1949, John Von Neumann introduced the concept of replicate computer program. His concept was used in a game called ‘Lore Wars’ in which players created tiny computer programs that attacked, erased and tried to propagate on an opponent’s system.
-In 1983, American electric engineer FRED COHEN first introduced the term ‘Computer Virus”.
-‘C-Brain’ is the first PC virus developed by Pakistani brothers (AMJAD AND ALVI) in 1987.
-After that, in 1988 stone (first boot sector virus) and Internet worm were introduced.
-In the 90’s, virus grew in more ratio.
-‘I love you’ is one of the world’s most prevalent and costly virus, introduced in 2000, which caused the loss of US$ 10 billion. It is said to have infected 1 in every 5 PCs worldwide.
-The first publicly known antivirus was produced by Bernt Fix in early 1987.
-Antivirus (1988)
-Dr. Solomon’s antivirus Toolkit (1988); released by Britan Alan Solomon.
-Norton Antivirus (1992); released by Peter Norton.
-Norton, Kaspersky, McAfee, AVG, Avast, etc. are common antivirus.
#Causes of creating antivirus:
1.To stop software piracy; software developers develop themselves.
2.For entertainment; by displaying different funny messages or pictures on the screen.
3.To show programming skills and talent.
4.To earn money by selling to software companies.
5.To steal sensitive information i.e., passwords, bank accounts, data, etc.
#Symptoms of computer virus:
1.Reduces memory space.
2.Changes size of computer files.
3.Changes the location and extension of files.
4.Slows down computers.
5.Deletes some portion of data from database.
6.Opens program automatically.
7.Slows unusual error messages frequently on the screen.
Types of computer virus:
1.Boot Sector or Start up Infector: Hides generally in boot sector, in either bootable disk or hard drive. Boot sector is a small program that is the first part of the operating system that the computer loads. It contains a tiny program that tells the computer how to load the rest of the OS. A computer is infected if it is booted from infected floppy disk, CD or hard disk.
Ex: C-Brain, Michelangelo, Disk Killer, etc.
2.System Infector or OS Infector: It infects various parts of OS. It corrupts the file having extension .com, .exe or .sys.
3.Application Program Infector or File Infector: It infects executable files or programs. An executable file can be a program file like Word or Excel, Access, etc. It gets attached to files which has .exe or .com extensions. It commonly spreads through pen drives, internet, CD, etc.
4.Message Carrying Virus: It doesn’t harm computer. It irritates user by displaying unwanted, vulgar messages.
5.Polymorphic Virus: It is harder to identify. Each of the copy of this virus is different. Ex; Phoenix, Evil, Proud and Cascade, etc.
6. Macros Virus: It infects macros within documents or template. It is activated when we open word or excel program and affects the normal program. Ex: DMV, etc.
7.Multipartite Virus: It is a hybrid of boot and program virus. It infects program files. It is loaded at the booting time.
8.Worm: It is self-replicating. It damages the normal functioning of computer system. It does not need to attach itself to an existing program.
9.Stealth Virus: It is unique file virus. It uses special techniques to hide its presence from users and virus scanners.
10.Trojan Horse: It attaches themselves to programs and don not replicate i.e., spread. It is used in computer network.
#Protection from virus:
-Do not use pirated software.
-Install Anti-virus software.
-Update Antivirus software on regular basis.
-Keep backup of data and programs.
-Scan portable disks (pen drives, portable hard disks) before using it.
-Do not download program from unknown websites.
-Check your E-mail attachments before using/opening it.
#Anti-Virus Software:
-It is a software that fights against computer virus.
-It is used to identify and remove computer viruses.
-Examples; Norton Antivirus (NAV), Avast, ASET Nod 32 Anti-Virus, Kaspersky, AVG Antivirus, McAfee Antivirus, Etc.
#Keywords:
(i)Fragmentation: The scattering of the part of the same disks file over different location.
(ii)Defragmentation: The process of rewriting part of a file to a contiguous sector on a hard drive/disk to increase the spread of processing.
(iii)Password: A password is a secret word or phrase that gives a user access to a particular system or file.
