But with an entire industry dedicated to cybersecurity issues, is it even conceivable that a virus attack could really cripple Internet access in the United States? "It would be very complicated, but it's possible," said Stephen Haag, professor in residence in the Department of Business Information and Analytics at the University of Denver.
"Because of the distributed nature of the Internet and the number of redundant backup systems, an event would have to target a number of network service providers," Haag said. "These maintain the infrastructure or backbone of the Internet. If one fails, then Internet traffic is simply routed among hundreds of other paths to get to its destination. So, the event would have to cripple many NSPs."
And again, there is always the specter of the unexpected. "You build firewalls to keep out things that you already know how they work and how they attack," Levinson said. "And that's great until some evil genius develops something that knows how to get around those firewalls."