Botnets Threaten the Internet

Every Internet user knows how viruses can turn computers into unwitting zombies secretly responsive to somebody else. One security expert says the Internet offers the possibility of the "perfect crime," one that provides high profit at low risk, and that the war to make the Internet safe "was lost long ago." The latest threat to Internet security is the "botnet" which can link thousands, or even millions, of computers together.  We hear what that could mean from David Farber of Carnegie Mellon University.