Introduction:
A computer computer Virus is a small software software program that spreads from from one computer to another computer 1. Why Compute Computerr viruse viruses s are are calle called d Virus Virus
Computer viruses are called viruses due to their similarities with biological viruses. In the same way that biological viruses enter the body and infect cells, computer viruses get into computers and infect files. Both types of virus can replicate themselves and spread, passing the infection from one infected system to another. Also, just as a biological virus is a microorganism, computer viruses are micro-programs. . !hy "o #eople Create Computer Viruses$ An infinite series of viruses found over the net are designed for different different objectives, some of these objectives are listed below% - &o gain control of or hac' a computer and use it for specific tas's - &o generate money by using such malware as a cash machine - &o steal sensitive information (credit card numbers, passwords, personal details, data, etc.) - &o prove that they are capable of writing a virus - *or +evenge against a company - &o cripple a computer or networ' . Damage Caused by Virus A computer computer virus can seriously damage or completely destroy files or software software on a computer. computer. &he result is that files may be lost permanently, educational educational programs may not function correctly or the overall performance of a computer may be slowed down. &he process involved in repairing the damage can be time consuming and epensive. Types of Viruses:
Resident Viruses
&his type of virus is a permanent per manent which dwells in the +A memory. *rom there it can overcome and interrupt all of the operations eecuted by the system% corrupting files and programs that are opened, closed, copied, renamed etc. /amples include% +ande, C0, eve, and r1lun'y. Direct ction Viruses
&he main purpose of this virus is to replicate and ta'e action when it is eecuted. !hen a specific condition is met, the virus will go into action and infect files in the directory or folder that
it is in and in directories that are specified in the A2&3/4/C.BA& file #A&5. &his batch file is always located in the root directory of the hard dis' and carries out certain operations when the computer is booted. !ver"rite Viruses
Virus of this 'ind is characteri6ed by the fact that it deletes the information contained in the files that it infects, rendering them partially or totally useless once they have been infected. &he only way to clean a file infected by an overwrite virus is to delete the file completely, thus losing the original content. /amples of this virus include% !ay, &rj.+eboot, &rivial.77.". #acro Virus
acro viruses infect files that are created using certain applications or programs that contain macros. &hese mini-programs ma'e it possible to automate series of oper ations so that they are performed as a single action, thereby saving the user from having to carry them out one by one. /amples of macro viruses% +ela, elissa.A, Bablas, 389:;1. Directory Virus
"irectory viruses change the paths that indicate the location of a file. By eecuting a program (file with the etension ./4/ or .C3) which has been infected by a virus, you are un'nowingly running the virus program, while the original file and program have been previously moved by the virus. 3nce infected it becomes impossible to locate the original files. $T Virus
&he file allocation table or *A& is the part of a dis' used to connect information and is a vital part of the normal functioning of the computer. &his type of virus attac' can be especially dangerous, by preventing access to certain sections of the dis' where important files are stored. "amage caused can result in information losses from individual files or even entire directories. Worms A worm is a program very similar to a virus< it has the ability to self-replicate, and can lead to negative effects on your system and most importantly they are detected and eliminated by antiviruses.
/amples of worms include% #=!Bugbear.B, >ovgate.*, &rile.C, =obig.", apson. Tro%ans or Tro%an &orses
Another unsavory breed of malicious code are &rojans or &rojan horses, which unli'e viruses do not reproduce by infecting other files, nor do they self-replicate li'e worms.
T!' 1( C!#')T*R VIR)+*+ ,ove ,etter Virus: &he worm originated in the #hilippines on ? ay @@@ and spread across
the world in one day, moving on to 5ong 1ong and then to /urope and the 2=, causing an estimated DE.E billion in damage. By ay @@@, E@ million infections had been reported CI& Virus% &he virus was detected as early as 887, but its payload was first triggered April F,
888 Atleast E la'h computers were affected in middle east and Asia #elissa Virus % *irst found on arch F, 888, elissa shut down Internet mail systems that got
clogged with infected e-mails propagating from the virus. Code Red Virus% &he Code Red "orm was a computer worm observed on the Internet on 0uly , @@ but the
largest group of infected computers was seen on 0uly 8, @@. 3n this day, the number of infected hosts reached E8,@@@. -agle virus: Bagle infected usersG systems using an e-mail attachment but then scoured !indows files for email addresses it could use to replicate itself. 5owever, the real damage came when it opened a bac' door to a &C# port that can be used by remote users and applications to access any 'inds of data on the infected system. -laster %
estimated "amage% between $2 and $10 billion; hundreds of thousands of infected PCs icrosoft announced a !indows vulnerability in @@. A short while later, that !indows vulnerability was eploited with a worm called =Blast< +asser:
/stimated "amage% tens of millions of dollars; =asser began spreading on April @, @@?< it eploited a security flaw in non-updated !indows @@@ and !indows 4# systems. !hen successfully replicated, the worm would scan for other unprotected systems and transmit itself to them #yDoom in ((/
/stimated "amage% slowed global Internet performance by 10 percent and Web load times by up to 50 percent 3n 0an. F, @@?, the y"oom worm spread across the Internet via e-mail. &he worm also transmitted itself as an attachment in what appeared to be an e-mail error message containing the tet Hail &ransaction *ailed.H Clic'ing on the attachment spammed the worm to e-mail addresses found in address boo's. +obig in ((0
/stimated "amage% 500000 computers worldwide; as much as $1 billion in lost producti!ity &he worm entered a computer in the form of harmless e-mail attachment +, +lammer in ((0 /stimated "amage% shut down "outh #oreas online capacity for 12 hours; affected 500000 ser!ers worldwide
&he virus affected servers, not #Cs. As viruses go, it was very small% a 9F-byte worm. It generated random I# addresses and sent itself to those I# addresses. If the I# address was a
computer running an unpatched copy of icrosoftGs => =erver "es'top /ngine, that computer would begin firing the virus off to other random I# addresses. =lammer infected 9E,@@@ computers in @ minutes. &o" to protect 'C
&o prevent viruses from entering a system there are basically just two options. &he first of these is to place the computer in a protective GbubbleG. &his in practice means isolating the machine< disconnecting it from the Internet or any other networ', not using any floppy dis's, C"-+3s or any other removable dis's. &his way you can be sure that no virus will get into your computer. ;ou can also be sure that no information will enter the computer, unless it is typed in through the 'eyboard. =o you may have a fantastic computer, the perfect data processing machine...but with no data to process. If youGre happy with that, your computer will be about as much use as a microwave oven. &he second option is to install an antivirus program. &hese are designed to give you the peace of mind that no malicious code can enter your #C. An antivirus program is no more than a system for analy6ing information and then, if it finds that something is infected, it disinfects it. &he information is analy6ed (or scanned) in different ways depending on where it comes from. An antivirus will operate differently when monitoring floppy dis' operations than when monitoring e-mail traffic or movements over a >AJ. &he principal is the same but there are subtle differences. #icro Virus 'rotection
a macro virus is a virus that is written in a macro language% that is to say, a language built into a software application such as a word processor. Among the precautions you ta'e, be sure to run up-to-date antivirus software on your computer, use digital signatures, and maintain a list of trusted sources of macros.
&o" to remove Viruses
&he most efficient method of removing is virus is to Install and Antivirus program. .
>ist of best Antivirus softwares . Bitdefender . 1aspers'y . !ebroot ?. Jorton E. /=/& Jod F. AVK Anitvirus 9. K "A&A 7. Avira 8. Vipre @. &rend icro &itanium 3perating should be regularly updated and chec'ed with different tools for any problems.
