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Copyright (c) 1988,90 Rob Rosenberger & Ross M. Greenberg Page 1 of 6
Computer Virus Myths
by Rob Rosenberger
with Ross M. Greenberg
A number of myths have popped up recently about the threat of computer
"viruses". There are myths about how widespread they are, how dangerous
they are, and even myths about what a computer virus really is. We'd like
the facts to be known.
The first thing to learn is that a virus is a malicious programming
technique falling in the realm of "Trojan horses." All viruses are Trojan
horses, but few Trojan horses can be called a virus.
That having been said, it's time to go over the terminology we use when we
lecture:
BBS Bulletin Board System. If you have a modem, you can call a BBS and
leave messages, transfer computer files back & forth, and learn a
lot about computers. (What you're reading right now, for example,
most likely came to you from a BBS.)
Bug an accidental flaw in the logic of a program which makes it do
things it shouldn't really be doing. Programmers don't mean to put
bugs in their program, but they always creep in. Programmers tend
to spend more time debugging their programs than they do writing
them in the first place. Inadvertent bugs have caused more data
loss than all the viruses combined.
Hacker someone who really loves computers and who wants to push them to
the limit. Hackers have a healthy sense of curiosity: they try
doorknobs just to see if they're locked, and they tinker with a
piece of equipment until it's "just right." The computer revolu-
tion itself is a result of hackers.
Shareware
a distribution method for quality software available on a "try
before you buy" basis. You pay for the program only if you find it
useful. Shareware programs can be downloaded from BBSs and you are
encouraged to give evaluation copies to friends. Many shareware
applications rival the power of off-the-shelf counterparts, at just
a fraction of the price. (You must pay for the shareware you
continue to use ── otherwise you're stealing software.)
Trojan
horse a generic term describing a set of computer instructions purposely
hidden inside a program. Trojan horses tell a program to do things
you don't expect it to do. The term comes from a legendary battle
in which the ancient city of Troy was offered the "gift" of a large
wooden horse that secretly held soldiers in its belly. The Trojans
rolled it into their fortified city....
Virus a term for a very specialized Trojan horse which spreads to other
computers by secretly "infecting" programs with a copy of itself.
A virus is the only type of Trojan horse which is contagious, like
Computer Virus Myths Page 2 of 6
the common cold. If it doesn't meet this definition, then it isn't
a virus.
Worm a term similar to a Trojan horse, but there is no "gift" involved.
If the Trojans had left that wooden horse outside the city, they
wouldn't have been attacked. Worms, on the other hand, can bypass
your defenses without having to deceive you into dropping your
guard. An example is a program designed to spread itself by
exploiting bugs in a network software package. Worms are usually
released by someone who has normal access to a computer or network.
Wormers the name given to the people who unleash destructive Trojan horses.
Let's face it, these people aren't angels. What they do hurts us.
They deserve our disrespect.
Viruses, like all Trojan horses, are purposely designed to make a program
do things you don't expect it to do. Some viruses are just an annoyance,
perhaps only displaying a "Peace on earth" greeting. The viruses we're
worried about are designed to destroy your data (the most valuable asset of
your computer!) and waste your valuable time in recovering from an attack.
Now you know the difference between a virus and a Trojan horse and a bug.
Let's get into some of the myths:
"All purposely destructive code comes as a virus."
Wrong. Remember, "Trojan horse" is the general term for purposely
destructive code. Very few Trojan horses are actually viruses.
"Viruses and Trojan horses are a recent phenomenon."
Trojan horses have been around since the first days of the computer.
Hackers toyed with viruses in the early 1960s as a form of amusement. Many
different Trojan horse techniques were developed over the years to embezzle
money, destroy data, etc. The general public wasn't aware of this problem
until the IBM PC revolution brought it out into the spotlight. Banks were
still covering up computerized embezzlements six years ago because they
believed they'd lose customers if word got out.
"Viruses are written by hackers."
Yes, hackers have written viruses. So has a computer magazine pub-
lisher. Trojan horses were written for decades by middle-aged men wearing
business suits. We call people "wormers" when they abuse their knowledge
of computers. You shouldn't be afraid of hackers just because they know
how to write viruses. This is an ethics issue, not a technology issue.
Hackers know a lot about computers; wormers abuse this knowledge. Hackers
(as a whole) got a bum rap when the mass media corrupted the term.
"Computer viruses are reaching epidemic proportions."
Wrong again. Viruses may be spread all over the planet but they won't
take over the world. There are about 150 or so known "strains" at this
time and some of them have been completely eliminated. Your chances of
being infected are slim if you take the proper precautions. Yes, it's
still safe to turn on your computer!
"Viruses could destroy all the files on my disks."
Yes, and a spilled cup of coffee will do the same thing. If you have
adequate backup copies of your data, you can recover from any virus/coffee
attack. Backups mean the difference between a nuisance and a disaster. It
Computer Virus Myths Page 3 of 6
is safe to presume there has been more accidental loss of data than loss by
viruses and Trojan horses.
"Viruses have been documented on over 400,000 computers."
This statistic comes from John McAfee, a self-styled virus fighter who
seems to come up with all the quotes the media love to hear. If you assume
it takes five minutes to adequately document a viral infection, you have to
wonder where Mr. McAfee got almost four man-years to document a problem
which is less than four years old. We further assume his statistics
include every floppy disk ever infected with a virus, as well as all of the
computers participating in the Christmas & InterNet worm attacks. (Worms
cannot be included in virus infection statistics.) The press doesn't
really understand computer crimes, so they tend to call almost anything
a virus.
"Viruses can be hidden inside a data file."
Data files can't wreak havoc on your computer ── only an executable
program file can do that. If a virus were to infect a data file, it would
be a wasted effort. But let's be realistic: what you think is 'data' may
actually be an executable program file. For example, batch files