Clive Thompson

The Virus Underground

from the New York Times Magazine

This is how easy it has become.

Mario stubs out his cigarette and sits down at the desk in his bedroom. He pops into his laptop the CD of Iron Maiden's Number of the Beast, his latest favorite album. "I really like it," he says. "My girlfriend bought it for me." He gestures to the fifteen-year-old girl with straight dark hair lounging on his neatly made bed, and she throws back a shy smile. Mario, sixteen, is a secondary-school student in a small town in the foothills of southern Austria. (He didn't want me to use his last name.) His shiny shoulder-length hair covers half his face and his sleepy green eyes, making him look like a very young, languid Mick Jagger. On his wall he has an enormous poster of Anna Kournikova-which, he admits sheepishly, his girlfriend is not thrilled about. Downstairs, his mother is cleaning up after dinner. She isn't thrilled these days, either, But what bothers her isn't Mario's poster. It's his hobby.

When Mario is bored-and out here in the countryside, surrounded by soaring snowcapped mountains and little else, he's bored a lot-he likes to sit at his laptop and create computer viruses and worms. Online, he goes by the name Second Part to Hell, and he has written more than one hundred and fifty examples of what computer experts call "malware": tiny programs that exist solely to self-replicate, infecting computers hooked up to the Internet. Sometimes these programs cause damage, and sometimes they don't. Mario says he prefers to create viruses that don't intentionally wreck data, because simple destruction is too easy. "Anyone can rewrite a hard drive with one or two lines of code," he says. "It makes no sense. It's really lame." Besides which, it's mean, he says, and he likes to be friendly.

But still-just to see if he could do it-a year ago he created a rather dangerous tool: a program that autogenerates viruses. It's called a Batch Trojan Generator, and anyone can download it freely from Mario's Web site. With a few simple mouse clicks, you can use the tool to create your own malicious "Trojan horse." Like its ancient namesake, a Trojan virus arrives in someone's e-mail looking like a gift, a JPEG picture, or a video, for example, but actually bearing dangerous cargo.

Mario starts up the tool to show me how it works. A little box appears on his laptop screen, politely asking me to name my Trojan. I call it the "Clive" virus. Then it asks me what I'd like the virus to do. Shall the Trojan Horse format drive C:? Yes, I click. Shall the Trojan Horse overwrite every file? Yes. It asks me if I'd like to have the virus activate the next time the computer is restarted, and I say yes again.

Then it's done. The generator spits out the virus onto Mario's hard drive, a tiny 3k file. Mario's generator also displays a stern notice warning that spreading your creation is illegal. The generator, he says, is just for educational purposes, a way to help curious programmers learn how Trojans work.

But of course I could ignore that advice. I could give this virus an enticing name, like "britney_spears_wedding_clip.mpeg," to fool people into thinking it's a video. If I were to e-mail it to a victim, and if he clicked on it-and didn't have up-to-date antivirus software, which many people don't-then disaster would strike his computer. The virus would activate. It would quietly reach into the victim's Microsoft Windows operating system and insert new commands telling the computer to erase its own hard drive. The next time the victim started up his computer, the machine would find those new commands, assume they were part of the normal Windows operating system and guilelessly follow them. Poof: everything on his hard drive would vanish-e-mail, pictures, documents, games.

I've never contemplated writing a virus before. Even if I had, I wouldn't have known how to do it. But thanks to a teenager in Austria, it took me less than a minute to master the art.

Mario drags the virus over to the trash bin on his computer's desktop and discards it. "I don't think we should touch that," he says hastily.

Computer experts called 2003 "the Year of the Worm." For twelve months, digital infections swarmed across the Internet with the intensity of a biblical plague. It began in January, when the Slammer worm infected nearly 75,000 servers in ten minutes, clogging Bank of America's ATM network and causing sporadic flight delays. In the summer, the Blaster worm struck, spreading by exploiting a flaw in Windows; it carried taunting messages directed at Bill Gates, infected hundreds of thousands of computers, and tried to use them to bombard a Microsoft Web site with data. Then in August, a worm called Sobig.F exploded with even more force, spreading via e-mail that it generated by stealing addresses from victims' computers. It propagated so rapidly that at one point, one out of every seventeen e-mail messages traveling through the Internet was a copy of Sobig.F. The computer-security firm mi2g estimated that the worldwide cost of these attacks in 2003, including clean-up and lost productivity, was at least $82 billion (though such estimates have been criticized for being inflated).

The pace of contagion seems to be escalating. When the

Mydoom.A e-mail virus struck in late January, it spread even faster than Sobig.F; at its peak, experts estimated, one out of every five e-mail messages was a copy of Mydoom.A. It also carried a nasty payload: it reprogrammed victim computers to attack the Web site of SCO, a software firm vilified by geeks in the "open source" software community.

You might assume that the blame-and the legal repercussions- for the destruction would land directly at the feet of people like Mario. But as the police around the globe have cracked down on cybercrime in the past few years, virus writers have become more cautious, or at least more crafty. These days, many elite writers do not spread their works at all. Instead, they "publish" them, posting their code on Web sites, often with detailed descriptions of how the program works. Essentially, they leave their viruses lying around for anyone to use.

Invariably, someone does. The people who release the viruses are often anonymous mischief-makers, or "script kiddies." That's a derisive term for aspiring young hackers, usually teenagers or curious college students, who don't yet have the skill to program computers but like to pretend they do. They download the viruses, claim to have written them themselves, and then set them free in an attempt to assume the role of a fearsome digital menace. Script kiddies often have only a dim idea of how the code works and little concern for how a digital plague can rage out of control.

Our modern virus epidemic is thus born of a symbiotic relationship between the people smart enough to write a virus and the people dumb enough-or malicious enough-to spread it. Without these two groups of people, many viruses would never see the light of day. Script kiddies, for example, were responsible for some of the damage the Blaster worm caused. The original version of Blaster, which struck on August 11, was clearly written by a skilled programmer (who is still unknown and at large). Three days later, a second version of Blaster circulated online, infecting an estimated seven thousand computers. This time the FBI tracked the release to Jeffrey Lee

Parson, an eighteen-year-old in Minnesota who had found, slightly altered, and rereleased the Blaster code, prosecutors claim. Parson may have been seeking notoriety, or he may have had no clue how much damage the worm could cause: he did nothing to hide his identity and even included a reference to his personal Web site in the code. (He was arrested and charged with intentionally causing damage to computers; when his trial begins, probably this spring, he faces up to ten years in jail.) A few weeks later, a similar scene unfolded: another variant of Blaster was found in the wild. This time it was traced to a college student in Romania who had also left obvious clues to his identity in the code.