FREE ESSAY ON COMPUTER VIRUSES

COMPUTER VIRUSES

Almost every End-user in the world has heard of computer viruses and/or has had one at one
point in time. Don't worry if you haven't heard about them, you won't find it in your
bloodstream. Unfortunately you may find one in your computer memory or disk storage. "
Some may be as benign as the common cold and others as deadly to your hard drive as the
Ebola virus ".
- 1 -What is a Computer Virus?
~ Usually defined as " a malicious code of computer programming" it is actually just
another software, only written with not so noble intentions.
~ A computer virus is designed to install, reproduce itself and cause damage to computer
files and data without the users knowledge or permission.
~ A computer virus can only survive and attack in computer memory, which is usually RAM
and disk storage.
~ You will not find a computer virus in your monitor or keyboard.
How will the virus invade your computer?
~ All viruses enter the system through two main points.
~ Disk drive 
~ Network adapter cards.
~ Disk drives may be any type (hard, floppy, CD and whatever you have). This makes
anything you insert in your drive a possible source of infection.
~ The network adapter card is most likely your connection to the Internet. Viruses enter
here most likely disguised as e-mail attachments. These attachments are often program
files and office documents containing macros. Besides e-mail attachments, there are
certain WebPages that contain harmful programming codes that may transfer into your
computer as virus or virus-like codes.
How do viruses spread?
~ After entering the computer memory, A virus often immediately sets out to multiply and
spread duplicate copies of itself across the main data storage device. It does this by
copying itself into as many files as it can on the disk drive. Later when users transfer
or copy these files to their friends and colleagues, the virus can gain entry to all of
their systems. If the virus has come this far on its path, the user may have permanent
damage to data and hardware. Such a level of infection only happens to two types of
users, those who do not install good anti-virus programs and those who do not update
their programs on a monthly basis. As a result newer viruses can actually use the
anti-virus programs to infect an even greater number of files.
Four main types of viruses ~
1) Boot sector viruses are usually transmitted when an infected floppy disk is left in
the drive and the system is rebooted. The virus is read from the infected boot sector of
the floppy disk and written to the master boot record of the system's hard drive. The
master boot sector is the first place your system reads from when booting up from the
hard drive. Then whenever the computer is booted up, the virus will be loaded into the
system's memory.
2) Program or file viruses are pieces of viral code that attach themselves to executable
programs. Once the infected program is run, the virus is transferred to your system's
memory and may replicate itself further.
3) Macro viruses are currently the most commonly found viruses. They infect files run by
applications that use macro languages, like Microsoft Word or excel. The virus looks like
a macro in the file, and when the file is opened, the virus can execute commands
understood by the application's macro language.
4) Multipartite viruses have characteristics of both boot sector viruses and file
viruses. They may start out in the boot sector and spread to the applications, or vice
versa.
While not technically viruses, other malicious programs like worms and Trojan horses
usually get stuck in there too. A worm is a program that replicates itself but does not
necessarily infect other programs. Just like in the Greek myth, Trojan horses contain a
concealed surprise. A Trojan horse program lies hidden in another seemingly harmless
piece of software until some condition triggers its awakening.
Why are they called viruses?
The term virus is more recent, and was first used in 1984 by Professor Fred Cohen to
describe self-replicating programs. The earliest PC viruses came a bit later in 1986. The
name is appropriate because like a biological virus, a computer virus is small, makes
copies of itself and cannot exist without a host.
How to check for viruses?
Some signs that you may have a computer virus are: Unusual messages or displays on your
monitor, Unusual sounds or music played at random times, Your system has less available
memory than it should, a disk or volume name has been changed, programs or files are
suddenly missing. Unknown programs or files have been created or some of your files
become corrupted or suddenly don't work right. There are special programs that can check
your system for known viruses called virus checks.
Recent viruses!
On May 27, 2000 a new virus was discovered. Computer security companies reported that
several corporate e-mail systems have already been infected and shut down as a result1.
This virus is known as the " killer resume"2 because it arrives pretending to be a resume
from a potential job applicant. The virus is attached to an e-mail with the subject
"Resume-Janet Simons". The document used is called Explorer.Doc or Resume.Doc. When
someone opens the word file, the file first spreads itself by sending an e-mail to
everyone in the user's Microsoft Outlook address book. Then it makes that person's
computer inoperable by deleting important files. While only Outlook users can spread the
virus anyone with a computer running the Windows operating systems who pens the infected
word document can have their files erased. The FBI advised users not to open any e-mail
with the subject line "Resume-- Janet Simons", to deactivate the executive feature in
Outlook, and then delete the e-mail without opening it.
On May 19, 2000 a different virus was detected except this time it is harder to trace.
The virus known as VBS.LoveLetter.F.W.A. is also known as many other names. This new
version of the love bug is actually a worm. It is a type of virus that propagates by
sending itself from computer to computer. This "Love Bug" has characteristics of both
Worm and Virus. The virus has been detected in Europe, Israel and along the West Coast of
the U.S. It is really an Internet worm that uses MSOL to spread itself as an attachment
with the subject line " FW: (attached file name)" along with the attachment listed in the
subject line. The virus changes itself to elude detection by virus programs. Every time
it is run it changes its name so it cannot be detected. The virus also renames files on
PC's and across networks, making the files unusable unless they have been backed up. The
virus only affects Windows 95,98,NT, & 2000. 
Remember there are thousands of viruses in circulation at all times, here are a few last
tips to protect you from infecting your computer3:
 Don't take e-mail from strangers.
 Watch the Net- be careful when downloading from sites that are not checked.
 Spread the word- Let your household users aware of these tips.
 Check your Floppies-Scan all outside floppies to make sure they are virus free.
 Back it Up-The best way to protect your data is to back it up on a regular
basis.
 Stay Current-Update your antivirus program on a monthly basis.
 Arm your computer- make sure you have a good antivirus program
Bibliography
Bibliography
What is a Virus?(http://gould_teri.tripod.com/sheridan/what is a virus.htm), November
7,2000.
Schmauder, Phil. "Virus Proof" The ultimate guide to protecting your PC, March 1998
Smith, George. "The Virus Creation Labs: A journey into the underground", December 1994.