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Dated: Aug. 13, 2004

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Network Security

By Najmi

A virus is a program written to copy itself and to transfer itself from computer to computer. Pretty much like a human virus or a common cold virus a computer virus is contagious, slows down or shuts down available resources and can be prevented against or cured.

A virus is a malicious piece of code or computer program designed to propagate and cause damage to files and data.

Here is a long list of horrible things that could happen to your machine:

  • Applications take longer to load

  • Files go missing

  • Computers becomes slow

  • Abnormal files appear

  • Word processors documents show garbage

  • Mysterious error messages crop up when you run programs

  • You get registry errors

  • Windows crashes often


  • Random files appear on disk drives

  • Hard drives keep coming out of space

  • Changed volume labels

  • Hardware problems (modem, printer issues)

  • Disabled ports

  • Altered system time/date

  • System freezes/hangs frequently

The extent of damage a virus is capable of is measured by the amount of time it takes to set things the way they ought to be. Common sources of contracting a virus are floppy disks, CDs, unsecured computers, laptops etc. However in present day the greatest threat or at least greatest perceived threat of a source of virus is email.

Well you cannot get a virus in the text of the email; it is the attachment accompanying the mail that contains the virus. You are safe until the time you have opened the email but once you download the attached file - that's where your worries begin. Mostly but not necessarily a virus appears as an ". exe" or ".com" attachment. The best precaution is to be highly suspicious of any runnable or executable file that appears from any source, known or unknown.

According to a recent study there are more than 60,000 malicious viruses in cyber space today and to add to the list, between 400 to 500 new viruses are discovered each month with 55% of them encountered through emails.

Lets look at some of the viruses that gained a lot of coverage due to the extent of damaged they caused.

The Chernobyl Virus

The virus originated in Taiwan in early June, 1998 however it was noticed in 1999 when it unleashed a wave of mayhem. This virus attacks the basic input/output system or BIOS. The BIOS acts as an interface between the hardware and the operating system and controls function like booting the computer when the reset button is hit.

The Chernobyl virus is overwrites the BIOS in a computer, leaving the PC unbootable. The Chernobyl virus threat is still alive and the latest warning was for the 26th of April 2002.

The Melissa Virus

The Melissa Virus arrived via email in spring 1999. It bore the message: "Here is that document you asked for…. Do not show anyone else".

A word document would come attached with the mail. The dangerous bit about this virus was that it had the ability to send itself out to the first fifty people in your mail address and recipient would receive your name in the "From" field.

I Love You Virus

I Love You Virus transmit itself via email, picking up all the addresses from the infected computer's mailbox. Against the name of the infected PC owner would appear in the "From" field of the email message. The message would ask the recipient to check the attached Love Letter. Once the attachment was opened -boom!

This virus/infected attachment was written on Visual Basic macro that could run by Microsoft Office products only. If a system did not have MS Office or Outlook installed the virus could cause no harm.

How does a user protect him/herself from a virus threat?

Here is a summary of some of the common advice that has been passed on by experts of the computer industry:

  • Never download or run an attached file on email that has been received from a stranger or from an unknown address.

  • Never set your program to automatically run attached files. This is especially true for browsers and email programs that automatically execute MS Word after opening emails.

  • Use famous Antivirus software's such as Norton and McAfee Antivirus and constantly update them at least once in a month through Internet.

  • Use Yahoo mail and Hotmail where there is a virus scanning system that is more elaborate and stringent than the one's we usually have available on our PC.

  • Always try to scan all attachments.

  • If you are using a disk from one computer to another it is very important to scan it before using it. Performing a virus scan on the floppy disk before copying, opening or running any files on it would prevent infection.

  • Disable floppy disk booting and this will eliminate the risk of a boot sector virus coming in from a floppy disk and accidentally left in the drive.

  • Make sure that macro virus protections is enabled in all Microsoft applications. Avoids running macros in a document unless you know what they do.

  • Check for double extensions. Some viruses and Trojans come embedded in files that are not what they appear to be. A file may be named sweet16.jpej.exe, take it for an image file, and eagerly open it, thus executing the malicious code.

  • Keep email softwares/pograms up-to-date. Vendors are adding features and safeguards continually to help manage the virus problem. You should frequently check for updates of your email programs to ensure that you have the latest and maximum protection.


Now that you've gotten free know-how on this topic, try to grow your skills even faster with online video training. Then finally, put these skills to the test and make a name for yourself by offering these skills to others by becoming a freelancer. There are literally 2000+ new projects that are posted every single freakin' day, no lie!

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Michael Gaisie's Comment
A very good tutorials for peole like us who want to knwow more about computing. Thank you.
13 Fri May 2011
Admin's Reply:

you're welcome