Introduction to Computer Viruses
It's Saturday morning. You boot up your Windows 98 computer and lo and behold, the graphics on the desktop are a mirror image of what they should be. Congratulations, you have a computer virus!
According to "Virus Bulletin," the Oxfordshire, England-based technical journal that tracks viruses, this new virus flips any uncompressed bitmaps horizontally, but only on Saturdays. This bulletin credits GriYo of the 29A virus-writing group as the author of this 32-bit polymorphic Windows virus now known as HPS (Hantavirus Pulmonary Syndrome).
Panda Software of Spain has announced that it has the antidote to HPS. Meanwhile, other antivirus companies scramble to code a cure for this Windows 98 desktop graphics virus.
So far HPS appears, like many viruses, to be harmless and humorous. According to the book "Computer Viruses" by Robert Slade (Springer, 1996), "The truth is that relatively few viral programs perform any overt damage to a system." However, no matter how harmless any virus may appear to be, people worry that it might do something else, perhaps on some Friday the 13th or maybe, who knows Jan. 1, the year 2000. Even if GriYo had the best of intentions, people worry that a mistake buried somewhere in his HPS code might accidentally cause harm.
Let's face it. Turn a computer virus loose and you can become mighty unpopular -- regardless of how harmless, funny, or even beneficial you believe your virus might be. People don't like to have programs running on their computers unless they make the decision to put them there.
In this Guide you will learn:
* What is a computer virus?
* Types of computer viruses
* Why study and create viruses?
* How to catch them
* How to fight them
One of the nice things about the recent escalation in computer crime is that the media doesn't make such a big fuss over viruses any more. Sure, they (viruses and the media both) can be a pain. However, with all those antivirus programs we can call upon for help, and with almost everyone now understanding the importance of frequent backups, viruses are no big deal, right?
"Computer viruses are no big deal." Famous last words? Digital viruses may be the first stages of artificial life. Think about it -- are we ready yet to share the planet with artificial life? Will we find some means of friendly coexistence, just as we have learned to safely enjoy cheetahs, lions and wolves? Will viruses perhaps even evolve into helpful life forms that will end poverty and war, help us understand the meaning of life itself and even shed light on the nature of God? Or will some computer virus designer create code that evolves into something that destroys the human race? Or ... maybe you readers will get fed up with me hyping viruses and flame war me into hiding!
What is a Computer Virus?
In 1988 the Internet was shut down by the "Morris Worm," a self-replicating program coded by Robert Tappan Morris of the Chaos Computer Club. It used sendmail and finger exploits to break into and propagate from one Unix computer to another. By the time it had infected some 10% of the computers on the Internet, it was clogging essential Internet communications lines as the worm shipped around ever more copies of itself.
Yet many computer scientists say we shouldn't call the Morris Worm a computer virus.
Before the first computer virus was ever coded, in 1984, Dr. Fred Cohen wrote his doctoral thesis on the topic (published in his book "Computer Viruses," ASP Press, 1986). As a result, Cohen is credited by many with being the first to conceive of their existence. It is important to remember
-- Cohen is AGAINST computer viruses. He didn't invent them, but was the first to prove they could be created, and to foresee the damage they could cause. Purists hold by the definition of virus that appeared in Cohen's doctoral thesis: a computer virus is code that, when active, attaches itself to other programs....
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