Amer Neely
If you are going to be downloading software from the Internet (or anywhere else) you must accept the possibility that you stand a chance of getting a computer virus. What's a computer virus you ask?
A virus is a program which attaches itself to other programs and/or disks, and makes copies of itself whenever it can. It is vandalism by computer. Most viruses cause damage, either by design or accident; others merely become a nuisance by putting messages on your screen. The important thing to remember is that someone wrote the program on purpose. Viruses do not appear out of thin air or by accident. In all cases, you will have to scan your hard disk and *all* your floppy disks and remove (if possible) the culprit.
Viruses attach themselves to other files that are "exectuable". This means any file that can be loaded into your computer's memory and "run". Files ending in .exe; .com; .sys; .dll; .ovr are some common PC extensions for executable files. Image files (.jpg; .gif) are not good hosts for a virus, since they are not executable. Audio files and video files are other "safe" types. A compressed file (see my last article for more info) such as .zip, by itself is not dangerous, but it may contain an executable file which carries a virus. If this file is extracted and run, the virus will infect your system.
You cannot get a computer virus merely by downloading a file. It must be "run" somehow on your computer in order for it become active.
Recently, there have been a number of "macro viruses", which attach themselves to Microsoft Word documents. They are Word macros, which can cause a lot of problems if you happen to get one. These macros work by loading and running automatically when you load a document into the word processor. The Microsft Word macro language is very powerful, allowing access to a lot of system-level commands and functions. Almost *every* keystroke you make can be trapped and altered to do something else.
What can you do?
I - Proactive
Depending on your particular computing habits, you should get yourself a couple of virus scanners and run them on your system every so often. How often depends on how much downloading you are doing, and where you are getting your files from. The reason I suggest not just one scanner is that some viruses may be missed by one, but not likely by the other. Sometimes you will get "false negatives" (a scanner says a file is OK, when it is not) and "false positives" (the scanner says there is a virus, when there isn't). Running two scanners will give you more information to work with.
The best defense against viruses is knowing how they work, and practicing "safe computing". Like safe sex, it is a matter of common sense - being promiscuous without precautions will lead to problems in both cases.
If you are the only person using your computer, your task is a lot easier. If you have children or others who also use the computer, then they will have to either be educated in the wiley ways of viruses, or you will have to "quarantine" any new software until it has been checked out.
Here are some guidelines:
On 5 1/4" floppies, there is a little notch cut out of one side. When that notch is covered, usually by those little pieces of black or silver adhesive stuff that come with the disks, (ah, that's what those are!) the disk is write-protected.
II - Reactive
I hope you don't ever have to do any of this, but if you suspect you have a virus, or your scanner says you do - DON'T PANIC (yet). If your scanner is making noises like you have a virus, see if it can get rid of it. Use another scanner to double-check your system. If you have to, re-boot your system from your clean boot disk. Then run your virus scanner again, from a floppy if you can.
One thing to stress about re-booting your system. You should power the system right down, and leave it off for about 20-30 seconds. Don't just do a "soft" boot. The reason for this is that some viruses actually mimic the process of soft-booting your computer, while all the time they are still active in RAM. Shutting the system off for about half a minute guarantees that nothing is left in RAM - it takes that long for the electric charge to dissipate.
Hopefully you can rid your hard disk of the virus just with the steps above. The next step is to check *every one* of your floppy disks. A virus is usually active for some time before you become aware of it. I once got hit by a virus and had to check all my floppies - over 200 of them. Most of them had also been infected.
If you want to learn more about computer viruses, there are a number of resources. The best is likely in the Usenet groups. Try any of these:
The computer virus FAQ can be found in news.answers and comp.virus. You can also do a search on the web in any of the search engines.
Having said all that, I must qualify it by saying that any well- known FTP site is probably the safest place to get shareware or freeware programs. And besides the anonymous ftp sites, there are dozens of World Wide Web sites that you can browse in your search for new shareware or freeware. These are also very safe places to look for software. Some well-known ones are TUCOWS, SimTel, freewarenow, Stroud's. These places check uploads for viruses - they can't afford to have a bad reputation.
This doesn't mean that you will never get a virus, but in all the years I've been getting software from FTP sites, I've never once gotten a virus from one. But you should have an UP-TO-DATE virus program installed on your system, and make sure it scans any new software you put on your hard drive. Any scanner more than 3 or 4 months old is out-of-date.
WAREZ
Avoid at all costs anything referred to as "warez". Some people feel that it is OK to upload commercial software to a web site for others to download for free. This is not only illegal, but makes buying commercial software expensive, because the software publishers have to raise their prices to cover the lost income due to pirating.