Computer Virus
“A computer virus is a
program that may disturb the normal working of a computer system”. Virus attaches
itself to files stored on floppy disks, USBs, email attachments and hard disks.
A file containing a virus is called infected file. If this file is copied to a
computer, virus is also copied to the computer.
Activation of Virus
When the computer
virus starts working, it is called the activation of virus. A virus normally
runs all the time in the computer. Different viruses are activated in different
ways. Many viruses are activated on a certain data. For example, a popular
virus “Friday, the 13th” is activated
only if the date is 13 and the day is Friday.
According to Wikipedia “Computer viruses cause billions of dollars’ worth of
economic damage each year, due to causing systems failure, wasting computer
resources, corrupting data, increasing maintenance costs, etc.”.
Damages caused by virus
Computer virus cannot
damage computer hardware. IT may cause many damages to a computer system. A
virus can:
1. A computer virus can
damage data or software on the computer.
2. It can delete some or
all files on the computer system.
3. It can destroy all the
data by formatting hard drive.
4. It may display a
political or false message very few times.
Causes of Computer Virus
The following are the
main causes of a Computer Virus.
Infected Flash Drives or Disks
Flash drives and disks
are the main cause of spreading viruses. Flash drives and disks are used to
transfer data from one computer to other. A virus can also be copied from one
computer to other when the user copies infected files using flash drives and
disks.
Email Attachments
Most of the viruses
spread through emails. Email attachment is a file that is sent along with an
email. An email may contain an infected file attachment. Virus can spread if
the users opens and downloads an email attachment. It may harm the computer
when it is activated. It may destroy files on the hard disk or may send the virus
automatically to all email addresses saved in the address book.
Infected / Pornography websites
Thousands of insecure
websites can infect computer with viruses. Most of the websites with
pornographic materials are infected, so by visiting these websites the user’s
computer also gets infected by virus. These websites are developed to spread
viruses or other unethical material. The virus is transferred to the user’s
computer when this material is downloaded. These websites may access the
computer automatically when the users visit them.
Networks
Virus can spread if
when an infected computer is connected to a network. The internet is an example
of such network. When a user downloads a file infected with virus from the
internet, the virus is copied to the computer. It may infect the files stored
on the computer.
Pirated Software
An illegal copy of
software is called pirated software. Virus can spread if user installs pirated
software that contains a virus. A variety of pirated software is available in
CDs and from the internet. Some companies intentionally add virus in the
software. The virus is automatically activated if the user uses the software
without purchasing license.
Other types of Computer Virus
The following are some
well-known viruses.
CodeRed
It is a worm that
infects a computer running Microsoft IIS server. This virus launched DOS attack
on White House’s website. It allows the hacker to access the infected computer
remotely.
Nimba
It is a worm that
spreads itself using different methods. IT damages computer in different ways.
It modified files, alters security settings and degrades performance.
SirCam
It is distributed as
an email attachment. It may delete files, degrade performance and send the
files to anyone.
Melisa
It is a virus that is
distributed as an email attachment. IT disables different safeguards in MS
Word. It sends itself to 50 people if Microsoft Outlook is installed..
Ripper
It corrupts data from
the hard disk.
MDMA
It is transferred from
one MS Word file to other if both files are in memory.
Concept
It is also transferred
as an email attachment. It saves the file in template directory instead of its
original location.
One_Half
It encrypts hard disk
so only the virus may read the data. It displays One_Half on the screen when
the encryption is half completed.
Protection from Computer Virus
Virus infects computer
system if latest and updated version of an Antivirus program is not installed.
Latest Antivirus software should be installed on Computer to protect it from
viruses. A computer system can be protected from virus by following these
precautions.
1. The latest and updated
version of Anti-Virus and firewall should be installed on the computer.
2. The Anti-Virus
software must be upgraded regularly.
3. USB drives should be
scanned for viruses, and should not be used on infected computers.
4. Junk or unknown emails
should not be opened and must be deleted straightaway.
5. Unauthorized or
pirated software should not be installed on the computer.
6. An important way of
protection against virus is the use of back up of data. The backup is used if
the virus deletes data or modifies it. So back-up your data on regular basis.
There are some great software’s that can back up your data automatically.
7. Freeware and shareware
software from the internet normally contain viruses. It is important to check
the software before using them.
8. Your best protection
is your common sense. Never click on suspicious links, never download songs,
videos or files from suspicious websites. Never share your personal data with people
you don’t know over the internet.
ANT-VIRUS
1. SMADAV-for input
and output hard disk devices
2. FIREWALL-for
internet web site
OTHERS ANT-VIRUS
Ms. Essential
Kaspersky
Avg
Asset nod
Avast
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