Spafford likens the Morris worm to today's botnets, which are large volumes of compromised computers used to send spam.

"The software that turns systems into zombies and adds them to botnets are like slow-moving worms," Spafford says. "They don't cause a denial of service, but they do create a slow infiltration and they spread to other machines automatically. There are quite literally millions of machines -- some estimates are 100 million machines -- that are inside botnets."

While the Morris worm was a high-profile attack that took down large swaths of the Internet, today's Internet attacks are focused on individual systems and tend to be stealthy. Instead of curious college students breaking into systems for bragging rights, it's more common to see criminals infect systems with viruses designed to be invisible.

"The focus of today's Internet attacks are profits, and there are no profits in taking down the Internet," Bellovin says. "The sophisticated bad guys are being much more careful about the way they attack systems."

Although it caused far less damage than follow-on attacks, the Morris worm is remembered for its impact on the computer science community.