Journal of the Plague Years
The first computer network plague hit back in the computer Stone Age, in 1972. Then, as now, the net by and large ran itself. Every hour, the machines making up the net pass millions of electronic mail messages around, like a frantic game of blind man's buff with everyone blindfolded. Each machine tries to send its current mailbag of messages to a machine that isn't too busy and is a little closer to the addressees. Even with all the chaos, the machines manage to deliver most messages in a second or two.In Los Angeles in 1972, one of these machines---let's call it Maxwell---failed but nobody noticed. The failure caused the computer to tell its machine neighbors that there was a negative delivery cost to send electronic mail through it. Naturally, they all started sending their mail through Maxwell.
This wouldn't have been a problem, except that the net, to avoid congesting well-traveled routes, doesn't have fixed routes to send messages. Everything is decided on the fly as demand dictates. Thus, all Maxwell's neighbors told all their neighbors that they had a much smaller delivery cost than they really did. Consequently, all the computers two jumps away from Maxwell started sending their mail to computers one jump away from Maxwell. These computers, of course, were already sending all their mail to Maxwell. And so it went. Like pulling the plug in a full sink, all the electronic mail on the net quickly headed Maxwell's way---which rapidly brought the entire network down. Eight years later, on Monday, October 27, 1980, something similar happened in Boston.
The obvious system you might be thinking of now is the telephone system. It is more centrally controlled than the net, so you might assume that it's not prone to these kinds of problems. Yet on Monday, January 15, 1990, despite millions of dollars, hundreds of programmers, and decades of experience, the entire AT&T long-distance telephone network crashed---because of one faulty line in a million-plus-line computer program. On Saturday, September 5, 1992, five British Telecom exchanges crashed for a similar reason.
Imagine the effect of that happening to the software controlling either country's nuclear weapons. Of course, neither country spends quite as much on telephone safety as it does on weapons safety. On the other hand, as complex as they are, not even telephone systems are as complex---or as lethal---as weapons systems.
Let Slip the Dogs of War