Dec '01 Tools

The importance of protection against computer viruses cannot be stressed strongly enough. Even if you feel you are not really concerned about damage to the information on your own computer, by contracting a virus, you could unknowingly pass it on to someone else, causing severe damage to their system. Protect yourself and you'll also be protecting your friends and business associates.

What is a computer virus?

A virus is a small program that attaches itself to real programs. For example, a virus might attach itself to a program like Microsoft Word. Each time you run Word, the virus runs too, and gets another opportunity to reproduce itself by attaching to other programs.

An email virus is spread via email messages and usually reproduces by automatically mailing itself out to all the address it finds in the host computer's address book.

Worms are programs that use computer networks and security holes to replicate. 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 as well.

A Trojan Horse is a program that masquerades as one thing (like a game) but instead does damage to your system (like erasing your hard drive) when you run it. Trojan horses cannot replicate themselves automatically. They are implanted into another program to do their damage.

A virus is designed so it runs first when the legitimate program gets executed. The virus loads itself into memory and looks around to see if it can find any other programs on the disk. If it finds one, it modifies it to add the virus's code to the unsuspecting program. Then the virus launches the "real program." The user has no way to know that the virus ever ran. Behind the scenes, the virus has now reproduced itself, so two programs are now infected. The next time either of those programs is run, they infect other programs, expanding the circle of infected programs each time.

If one of the infected programs is given to another person via a disk, or downloading, then other programs also get infected, spreading the virus.
Most viruses also have some sort of damage phase where they wreak havoc. Some sort of trigger will activate the damage phase, and the virus will then do what is was programmed for which could be anything from printing a taunting message on your monitor to erasing your hard drive. The trigger to begin doing damage might be a specific date, the number of times the virus has been replicated, or any number of other variables.

Another type of virus has the ability to infect the boot sector on hard drives. The boot sector is a small program that is the first part of the operating system that a computer loads. The boot sector contains a tiny program that tells the computer how to load the rest of the operating system. By putting its code in the boot sector, a virus can guarantee it gets executed. It can load itself into memory immediately and it is able to run whenever the computer is on. Boot sector viruses can also infect the boot sector of any floppy disk inserted in the machine, and can spread if that disk is passed along to others.

How do you get a virus?

A virus typically comes as an ATTACHMENT in your email. Most bugs could be stopped in their tracks if everyone followed one simple rule => NEVER open an email attachment unless you know the person who sent it to you AND that person has previously told you that they will be sending you an attachment and the exact name of the attachment.

Email viruses that feed on a host's address book and send themselves to everyone they find there are especially insidious because the recipient is caught off guard by the fact that they are receiving an email from somebody they already know and communicate with. Again, if you receive an email with an attachment that you are not expecting, DO NOT open the attachment. Delete the email.

What can you do to prevent the spread of viruses?

You can purchase an Anti Virus program at your favorite software store or you can download one from a safe source off the Internet. After you install your Anti Virus program, run a complete check of your system and schedule yourself for periodic checks.

Even after you've installed and run your Anti Virus program, you will need to be sure to update the program on a regular basis. New viruses are constantly being created and you need to be protected against them too. An old version of an Anti Virus program won't protect against a new virus someone just concocted yesterday.

A virus can't reproduce on its own - it needs a host to carry it along... that's where you come in! Get the proper Anti Virus protection!

You can check your system online for free!

Trend Micro's HouseCall is a FREE service that will scan your computer for viruses while you are online. If any viruses are found during the scan, HouseCall will also send you the name of the virus, the number of infected files found and the number of files cleaned by HouseCall.

Beware of Hoax Viruses!

Is it really a virus? There are many false virus warnings making the rounds. The fear they spread and the annoyance of having to check each time you receive such a warning is almost as bad as receiving an actual virus. Before you pass along one of these false virus warnings, check it out at the Hoax Warnings site.