The Mistake
The critical error that transformed the worm from a potentially harmless intellectual exercise into a virulent denial of service attack was in the spreading mechanism. The worm could have determined whether to invade a new computer by asking if there was already a copy running. But just doing this would have made it trivially easy to kill; everyone could just run a process that would answer "yes" when asked if there was already a copy, and the worm would stay away. The defense against this was inspired by Michael Rabin's mantra, "Randomization." To compensate for this possibility, Morris directed the worm to copy itself even if the response is "yes", 1 out of 7 times. This level of replication proved excessive and the worm spread rapidly, infecting some computers multiple times. Morris remarked, when he heard of the mistake, that he "should have tried it on a simulator first."
Read more about this topic: Morris Worm
Famous quotes containing the word mistake:
“He took control of me for forty-five minutes. This time I’ll have control over him for the rest of his life. If he gets out fifteen years from now, I’ll know. I’ll check on him every three months through police computers. If he makes one mistake he’s going down again. I’ll make sure. I’m his worst enemy now.”
—Elizabeth Wilson, U.S. crime victim. As quoted in People magazine, p. 88 (May 31, 1993)
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—Henry David Thoreau (1817–1862)