So You Want a New Computer

Part Five: How to Protect Your Computer's Data

by Kevin Jay North, 27 Dec 99


Almost everyone has heard of computer viruses. They are indeed a real threat. But not many people understand how they work. This is important, because without factual information, you might take unnecessary precautions that hinder your work, or, more commonly, you take actions that put yourself at great risk.

Viruses are called such because of their similarity to biological viruses. In fact, once you really start studying computer viruses, the degree of similarity is quite remarkable. This does not mean, of course, that your computer can catch viruses out of the air like humans. But many other properties of the virus hold true.

The most important property is that a virus cannot live without a host. Unlike a bacterium, a biological virus cannot thrive on its own; it must enter a host cell, then interfere with the DNA and trick the cell into producing more viruses. A computer virus also cannot live on its own. It must attach itself to a computer program. A computer program is simply a list of instructions that the computer follows. Well, if a virus can add extra instructions to the list, it can make the computer do something else, like reproduce the virus. This is done by making the computer attach a copy of the virus on another computer program. Then, when you start running the other program, the virus reproduces itself again, and so on.

As with a biological virus, the computer virus usually does something else besides just reproduce. It was designed to inflict harm. Therefore, in addition to making copies of itself, the virus also does things like: 1) wrecking computer programs so they don't work anymore. 2) erasing important files of yours. 3) erasing your hard drive so your whole computer won't work anymore. 4) displaying irritating or offensive messages on the screen. Erasing your hard drive is terrible, but actually the more dangerous viruses are the ones that aren't as damaging -- this is because it takes longer to detect them. Once a person knows a computer is infected with a virus, he can get rid of it, but before this he's unwittingly spreading the virus to other people. The worst virus would be one that works on a time delay, like the biological AIDS virus. You may have it for years without symptoms, then one day, suddenly everything goes wrong all at once.

How do you protect yourself? It's actually very simple. Like the biological AIDS virus, computer viruses cannot be spread by "casual contact." There are specific things that have to happen before you can become infected. It's amazing that the AIDS biological virus is extremely preventable, yet it is spreading like wildfire because people do not want to modify their behavior and refrain from intimate relations outside of marriage. For the same reason, computer viruses are very preventable, but people are careless, so they continue to cause huge problems.

Anyway, there is no way your computer can get a computer virus unless you obtain and run an infected computer program. Both things have to happen: 1) you obtain the program, and 2) you run the program. So one good place to start is to not obtain any new programs. If your computer is not connected to the Internet, and if you never install any new computer programs (software) on it, and if you never copy files from someone else, you won't get a virus. Period.

Unfortunetly, now days this is very hard to do, especially if you're connected to the Internet. Your friends will probably be sending you "cool" programs and begging you to try them out. They may end up on your computer before you even know about it. Or even if you are not connected to the Internet, you might be perfectly fine for 2 years, except just once during those 2 years some teenage computer guru visits your house and borrows your computer, and during this time he puts a 3.5" floppy disk into it. Boom, there's another opportunity for a virus to come in.

So it's actually easier to attack the second point, which is to not run the new program. For example, if a friend sends you a computer program attached to an Email message, you can choose not to run it. Better yet, you can delete it so you don't accidentally run it later. If you're really strict about this, and you refuse to experiment with new programs, even if from a friend, you'll be safe.

Unfortunately, this requires a lot of discipline and control. Heck, even if you don't run any programs, another family member might do so accidentally when you're not looking. Or perhaps a teenage guru might run a new program when he's borrowing your computer. While I would certainly urge everyone to be careful and not obtain or run strange new computer programs, almost everyone needs an additional level of protection.

Virus Scanners

There is a computer program you can buy and install on your computer that scans the computer for viruses. Originally these programs worked like this: At a certain point in time, you run the program, and your computer's memory and entire hard drive are searched for viruses. If one is found, you are warned, and, in most cases, the virus is automatically removed. If the virus did any damage, it can't be repaired, but with the virus eliminated at least there won't be any further damage. The best time to run a virus scanner is immediately after receiving a new computer program and before you run it. This gives you the opportunity to eliminate the virus before it infects your computer and causes damage.

Modern virus scanners have this capability, but they also have an additional level of protection: They have what is often referred to as a "shield" program. This program runs continuously while you use your computer for other things. If a new virus enters memory or appears on the hard drive, it is immediately detected. This is great because, as I mentioned before, with the Internet you might not even know a new file is appearing on your hard drive.

Be aware, though, that a virus scanner does not give you complete protection, just like certain birth control methods do not give you complete proection against the biological AIDS virus. The scanner can only detect viruses it knows -- i.e., viruses known to exist at the time the scanner program was created. If the virus scanner was written in 1998 and someone in 1999 creates a brand new virus, the virus scanner won't be able to recognize it.

To help with this, modern virus scanners also can be updated. For example, McAfee VirusScan, the most popular scanner, has an Internet web site where you can "download" (i.e., copy to your computer) a free updated virus database that will allow your virus scanner to detect the newest viruses. This database is updated every month because literally thousands of new viruses are created each month. It is sad that human beings would be this malicious, but it is true.

But if you update your virus scanner faithfully each month, and you follow the other precautions I mentioned, the chances of your getting a virus will be very low. The people who are at much greater risk are those that don't bother to take precautions. It's funny that the Microsoft Windows operating system comes with a large number of built-in programs, including the Internet Explorer web browser which has been contraversial because Netscape belives it's unfair competition. Yet, despite all of the built-in stuff, there is no built-in virus scanner, even though viruses continue to be a huge program. I think all computers should have a virus scanner. It's worth the extra money (you can buy one for as low as $10 if you look around). Some new computers have a virus scanner pre-installed, so maybe your computer already has one. If it does, learn how to use it.

Microsoft Word Document Viruses

As I mentioned above, thousands of new viruses are created each month. The most dedicated computer hackers are always trying to find new and creative ways to make viruses. They know about the virus scanners, and they want to make new kinds of viruses that the virus scanners won't be able to detect. One more recent invention is the Microsoft Word Document virus.

This kind of virus really disturbs me because it broke the old (but now no longer true) rule that only regular computer programs could have viruses. Microsoft Word is a popular word processor program. Being a program, it can be infected with a virus, but the actual document files that you create with it used to be perfectly safe. A metaphor is like this: Word is the xerox copier, and the document files are the paper. The xerox machine can be infected, but the paper is safe.

This is no longer true. Microsoft keeps enhancing the format of the document files, and one of their more recent inventions was to allow mini computer programs to be attached to the document file. This was a terrible decision by Microsoft. I, being a computer scientist, know that there are some very interesting and useful things that you can do by mixing computer programs and documents. To think of the metaphor again, you could think of sticking an LCD clock on a piece of paper that you've just put through the xerox machine. The paper isn't alive, but the clock you've stuck on is, and now your document has been "enhanced."

But viruses had been around for years when Microsoft added this program mixing capability to Word documents, and they should have known better. The dangers far outweigh the benefits. This was a terribly foolish decision on Microsoft's part. Here's why: If you send a computer file to a friend via Email, or give the friend a file on a 3.5" floppy disk, you're not likely to give him a computer program. You're not supposed to copy commercial copyrighted computer programs anyway. But you would give him something like a Word document that contains a nice letter you wrote to him. And if the document contains a virus, now viruses have a much easier way to be exchanged!

This was a devastating blow to the computer industry. Ironically, few people even need the extra feature where you mix a mini computer program with a document. You aren't going to need to bother, for example, with a little LCD clock when you're writing a letter to a friend. But because the capability is there, it is possible for a mini computer program with a virus to attach itself to any document, including a letter you might write to Aunt Matilda.

So now you have to be on guard for any files, because a file that you receive, like a word processor document, might contain a mini computer program and a virus without your knowing it. If you're an expert like me, you may know which files are infectable and which ones are always safe, but otherwise, you have to be careful about everything. This is yet another reason to get a good virus scanner, because the scanner will check things out for you.

But the best thing you can do is to be careful who you get files from. If you obtain a computer program from, for example, you won't even need to worry about viruses because this is a legitimate, internationally-known company, and the last thing they need is a major CBS news story about some grandma getting an infected file from them and losing all of the data on her computer. You can be sure Microsoft has their own virus scanners and any file they make available is safe. If the file is from a small little company, be more suspicious. If it's from a friend, be suspicious (who knows where he got the file from?). If it's from someone you don't know, it's probably safer not even to take a chance!

This is similar, by the way, to my guidelines about truth on the Internet which I mentioned in Part 4. The rumor Email that you got... is that an official bulletin from Microsoft with full contact information listed, or is it just something anonymous forwarded by your friend with no contact information but only the admonition to "forward this to as many people as possible"? Be careful, not only with what you believe, but also with what you accept from someone.

If you follow this principle, you will protect yourself from future kinds of viruses. For example, I'm sure these evil people are working very hard at trying to make a virus that can infect a web page that can wreck your computer when you view the web page. Well, if you stick mainly with the mainline web sites like,,, etc., and not bother with strange web sites from people who make unsupportable claims, you probably won't have trouble. And if you update your virus scanner, it will probably be improved so that it can detect the new kind of virus.

(Note: As far as Email goes: If a friend sends you a file, like a computer program or a Word document, it usually appears as an icon in their Email message. It's safe to read the message, but if you double-click on the icon, the file is activated -- if it's a program, the computer runs it; if it's a Word document, Word is started automatically and the document immediately opened automatically. This is how you can be infected. If the file came from a trusted friend, and you have a virus scanner with a "shield" program running, it should check the file to make sure it's safe automatically for you. If the file came from someone you don't even know, or if you don't have a virus scanner program, it's better to delete the message!)

One more thing. Watch that teenage computer guru. Make sure he shares your sentiments about viruses before you let him "take over" your computer!

Backing Up Your Files

One more issue I'll talk about: Backing up your files. I talked a great deal about computer viruses, which are malicious computer programs deliberately written to wreck your computer. But don't forget that the computer might go bad on its own. It can break down just like a microwave or TV or VCR. If you were wise and got a good support contact, you can get it fixed. But in the meantime, you might lose a lot of data.

One of the worst things that could happen is that the hard drive could "crash" -- i.e., stop working. The hard drive contains all of your files, software, and other important information. Physically, it can easily be replaced, but you will lose all of the data on it. A modern computer comes with software pre-installed on your hard drive, but if you have to replace your hard drive, it also comes with a CD which you can use (assuming you have a CD-Rom) to re-install all of the original software. You can re-install other software, too. It takes time, but eventually you can get your computer going again.

But what you can't restore are your important files, like your word processor documents -- letters that you wrote to Aunt Matilda. Or a spreadsheet that might contain three years of important tax records. Etc. If these files are important to you that you want to keep them for a long time, you are wise to "back them up", which means making a copy of them.

You'll want to do this on a different storage medium altogether. You can easily make a duplicate copy of a file on the hard drive, but then you have two copies on the same hard drive, the same hard drive that can go bad and trash both files. But if you make a copy onto a 3.5" floppy disk, you can recover the file from the disk if the hard drive goes bad.

This is the easiest way to back up files. There are lots of other ways. For example, some people have tons of important files, too many to fit even on 50 floppy disks. They need to back up everything. They might buy a special "tape" drive and install it into their computer next to the CD Rom drive. The tape drive is slow, but each casette can typically hold several gigabytes of information, enough to back up everything on the entire hard drive.

There are many other similar systems. But each one is different and some are easier to deal with than others. Some are more reliable than others. For someone like you, who won't be using the computer that much except for simple things like surfing the web, checking Email and writing an occasional letter in a word processor, I don't recommend such a backup system. In my experience, they seem to be more trouble than it's worth.

I would suggest just buying a pack of fifty 3.5" diskettes and going with that. You can buy a pack for $20 or less. Then, at the end of each day, before you turn your computer off, you can take the most important files you worked on that day and copy them to a floppy disk. If you do this faithfully, you'll be safe. If you want to backup Email files and are not sure which files to back up, consult the manual or a friend to help. Or call the people who wrote the Email reader program. Or call your ISP. If you are regularly backing up tons and tons of files on multiple 3.5" disks, or if you have files that won't even fit on a single 3.5" disk, you might want to dive into a more complicated backup system. A friend or teenage computer guru can help you with this. But I still think for most beginning computer users the simple 3.5" diskette backup system is the simplest. Also note that you can give 3.5" disks to a friend, or receive them from a friend, to share files. If you get a special "tape" drive, it probably won't work on anyone else's computer.

I'll close with this neat saying that I heard: There are only two kinds of computer users: Those who have lost data in a crash... and those who will lose data in a crash. Most people don't realize the importance of backing things up until they lose something very important. If you're working on an important paper, you'll want to save your work to the hard drive regularly, and perhaps even make copies to a floppy disk every couple of hours. Even if the hard drive doesn't go bad, it's possible for a computer program to malfunction and unintentionally destroy the data in one file. If you don't have a backup somewhere else, you'll have lost everything. What and how much you back up is up to you, and you'll get a better idea with experience, but please be aware of this important issue.

Where to Go From Here

I could go on and on with more computer issues... there's a lot to learn! But I hope with this series I've covered the most important issues to get you started -- the ones people either don't talk about or the ones that people do talk about but are way over your head. If you purchased a computer with care, one that meets your needs, and if you plan to proceed slowly and carefully, finding a good ISP, getting a virus scanner, resisting the peer pressure from the computer guru who wants to change things around on your computer, then you should be well on your way to having a great computer experience and a computer that works for you, one that helps you with problems rather than makes a ton of new problems. And there are a lot of neat things on the Internet and World Wide Web to explore. Have fun!

-- Kevin Jay North

Document last modified 08 Jan 00. (C) 2000 by Kevin Jay North; see also full copyright notice & disclaimers..

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