Espaņol

The lowdown on viruses
by Erica Schaapveld
with special contribution from Jonathon Potter

Look at all of the ISTE technology standards you meet by knowing about viruses!

I. Technology operations and concepts.

VI. Social, ethical, legal, and human issues.

Click here for a detailed description.

omputer viruses, like their biological namesake, are host-reliant code that replicate themselves onto files, programs, and disks in your machine. Viruses exist only in an executable state; thus, they must be activated in order to cause harm. Some are malicious, erasing files or locking up your computer; others are simply irksome, taking up valuable memory, or displaying messages and images.

What are some examples of viruses?

Viruses fit into four main categories: Time Bombs, Logic Bombs, Worms, and Trojan Horses.

Time Bombs: detonate at a time designated by the virus’ creator causing memory to be erased, infecting the whole system or erasing the hard drive.

Logic Bombs: pieces of code that perform malicious acts, such as performing an endless loop of code or writing random files, ultimately causing the hard drive to overload, and subsequently, crashing the computer.

Worms: encoded as attachments in e-mail, they replicate themselves with or without altering the host and spread via the Internet to other hosts.

Trojan Horses: hidden inside a downloadable program, the code is activated when the program is first used, usually deleting the contents of your hard drive. Trojans do not spread by replicating themselves. Instead, people accidentally pass the program around.

here are also four subcategories of infection when viruses occur:

File Infectors: attach themselves to regular program files with an executable extension, such as .exe. Every time the program runs, the virus runs. This subcategory fits under any of the four main categories.

Cluster Infectors: alter the file system, allowing the virus to run prior to other programs. This subcategory applies mainly to Time Bombs and Logic Bombs.

Macro Viruses: use the auto-execution of macros in Microsoft Word to spread. This subcategory occurs most prominently with Logic Bombs.

System Infectors: residing in the boot-up sector, the virus is invoked every time the system is booted. This subcategory applies to both Time Bombs and Logic Bombs.

How did I get a virus and how can I prevent it in the future?

iruses seem to just appear in computers, but if a virus infects your computer system, it is usually due to one of the five following reasons:

Booting or running files and programs from an infected floppy: always scan floppies for viruses before running them, even if they are brand new. To do this follow the directions below:

1. Insert the disk into the appropriate drive.
2. Open your anti-virus software. I am using Norton.
3. Select the drive or disk you would like to scan. In the image below, Scan a floppy disk is selected.

4. Click the Run Scan Now button as shown above.

5. If problems are found, Norton automatically fixes them.
6. Click OK.

Running an infected program: if you know a program is infected, do not run it.

Running macros automatically: Microsoft Word should be set to always alert you with a prompt when a document contains macros. If you do not know the origin of the macros, disable them.

Opening e-mail or document attachments: if the origin of the e-mail is unknown or you do not recognize the document name, do not open it.

What do I do if I have a virus?

f your computer is acting peculiar, it may be a virus. Hopefully, the anti-virus program you use will be able to rid your machine of the bug. However, it is very important to always keep backup files of your documents and programs, so that if things go haywire you will not loose everything. Follow the steps below to diagnose the exact problem:

1. Scan with an anti-virus software, such as McAfee or Norton
2. If the anti-virus software locates a virus, it should be able to rid your machine of it.
3. If the software is unable to remove the error, as shown below, notify the company and they will be able to help you.

iruses are rare, but it is wise to take precautions. Having an anti-virus installed on your computer can save you precious time and worry. Always remember that viruses operate only when executed. Therefore, if you never open the infected files or run the programs, the virus will not be able to harm your system.