Strange as it may sound, the computer virus is something of an information age marvel. On one hand, viruses’ show us how vulnerable we are — a properly engineered virus can have a devastating effect, disrupting productivity and doing billions of dollars in damages. On the other hand, they show us how sophisticated and interconnected human beings have become.
For example, experts estimate that the Mydoom worm infected approximately a quarter-million computers in a single day in January 2004. Back in March 1999, the Melissa virus was so powerful that it forced Microsoft and a number of other very large companies to completely turn off their e-mail systems until the virus could be contained. The ILOVEYOU virus in 2000 had a similarly devastating effect. In January 2007, a worm called Storm appeared — by October, experts believed up to 50 million computers were infected with the virus. This year Confliker C Worm has attacked from 9 to 15 million computers around the world. That’s pretty impressive when you consider that many viruses are incredibly simple.
There are many different forms of electronic infections that plague computers. The most common are:
Viruses – A virus is a small piece of software that piggybacks on real programs. For example, a virus might attach itself to a program such as a spreadsheet program. Each time the spreadsheet program runs, the virus runs, too, and it has the chance to reproduce (by attaching to other programs) and wreak havoc.
E-mail Viruses – An e-mail virus travels as an attachment to e-mail messages, and usually replicates itself by automatically mailing itself to dozens of people in the victim’s e-mail address book. Some e-mail viruses don’t even require a double-click, they launch when you view the infected message in the preview window of your e-mail software.
Trojan Horses – A Trojan horse is simply a computer program. The program claims to do one thing (it may claim to be a game) but instead does damage when you run it (it may erase your hard disk). Trojan horses have no way to replicate automatically.
Worms – A worm is a small piece of software that uses computer networks and security holes to replicate itself. A copy of the worm scans the network for another machine that has a specific security hole. It copies itself to the new machine using the security hole, and then starts replicating from there.
Resident Viruses – This type of virus is permanent and dwells in the RAM memory. From there it can overcome and interrupt all of the operations executed by the system: corrupting files and programs that are opened, closed, copied or renamed.
Direct Action Viruses – The primary purpose of this virus is to replicate and take action when it is executed. When 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 AUTOEXEC.BAT file PATH. This batch file is always located in the root directory of the hard disk and carries out certain operations when the computer is booted.
Overwrite Virus – Viruses of this kind are characterized 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. The only way to clean a file infected by an overwrite virus is to delete the file completely, thus losing the original content.
Boot Virus – This type of virus affects the boot sector of a floppy or hard disk. This is a crucial part of a disk, in which information on the disk itself is stored together with a program that makes it possible to boot (start) the computer from the disk.
If you suspect that you may have a virus running on your computer or network, do not delay in getting the issue resolved! The longer a virus runs, the more damage they can cause to your computer and sometimes even the files or programs on the computer.
