7/17/2019 To Prevent Viruses From Entering a System There Are Basically Just Two Options

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Introduction:

 A computer Virus is a small software program that spreads from one computer to another

computer 

1. Why Computer viruses are called Virus

Computer viruses are called viruses due to their similarities with biological viruses. In thesame 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 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 virus can seriously damage or completely destroy files or software on a computer.&he result is that files may be lost permanently, educational programs may not function correctlyor the overall performance of a computer may be slowed down. &he process involved inrepairing the damage can be time consuming and epensive.

Types of Viruses:

Resident Viruses

&his type of virus is a permanent which dwells in the +A memory. *rom there it can overcomeand interrupt all of the operations eecuted by the system% corrupting files and programs thatare 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 aspecific condition is met, the virus will go into action and infect files in the directory or folder that

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it is in and in directories that are specified in the A2&3/4/C.BA& file #A&5. &his batch file isalways located in the root directory of the hard dis' and carries out certain operations when thecomputer is booted.

!ver"rite VirusesVirus 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, thuslosing the original content.

/amples of this virus include% !ay, &rj.+eboot, &rivial.77.".

#acro Virusacro viruses infect files that are created using certain applications or programs that containmacros. &hese mini-programs ma'e it possible to automate series of operations so that they areperformed 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'nowinglyrunning the virus program, while the original file and program have been previously moved bythe 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 partof the normal functioning of the computer.&his type of virus attac' can be especially dangerous, by preventing access to certain sectionsof the dis' where important files are stored. "amage caused can result in information lossesfrom 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 tonegative effects on your system and most importantly they are detected and eliminated byantiviruses.

/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 donot reproduce by infecting other files, nor do they self-replicate li'e worms.

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T!' 1( C!#')T*R VIR)+*+

,ove ,etter Virus: &he worm originated in the #hilippines on ? ay @@@ and spread acrossthe world in one day, moving on to 5ong 1ong and then to /urope and the 2=, causing anestimated 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 gotclogged 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 thelargest group of infected computers was seen on 0uly 8, @@. 3n this day, the number ofinfected hosts reached E8,@@@.

-agle virus:

Bagle infected usersG systems using an e-mail attachment but then scoured !indows files for e-mail addresses it could use to replicate itself. 5owever, the real damage came when it opened abac' door to a &C# port that can be used by remote users and applications to access any 'indsof data on the infected system.

-laster %estimated "amage% between $2 and $10 billion; hundreds of thousands of infected PCsicrosoft announced a !indows vulnerability in @@. A short while later, that !indowsvulnerability 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. !hensuccessfully replicated, the worm would scan for other unprotected systems and transmit itselfto them

#yDoom in ((//stimated "amage% slowed global Internet performance by 10 percent and Web load times byup to 50 percent 3n 0an. F, @@?, the y"oom worm spread across the Internet via e-mail. &he worm alsotransmitted itself as an attachment in what appeared to be an e-mail error message containingthe tet Hail &ransaction *ailed.H Clic'ing on the attachment spammed the worm to e-mailaddresses 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 500000ser!ers worldwide&he virus affected servers, not #Cs. As viruses go, it was very small% a 9F-byte worm. Itgenerated random I# addresses and sent itself to those I# addresses. If the I# address was a

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computer running an unpatched copy of icrosoftGs => =erver "es'top /ngine, that computerwould 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 intoa 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.

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&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?. JortonE. /=/& JodF. AVK Anitvirus9. K "A&A7. Avira8. Vipre@. &rend icro &itanium

3perating should be regularly updated and chec'ed with different tools for any

problems.