Back in November 1988, Robert Tappan Morris, son of the famous cryptographer Robert Morris Sr., was a 20-something graduate student at Cornell who wanted to know how big the internet was – that is, how many devices were connected to it. So he wrote a program that would travel from computer to computer and ask each machine to send a signal back to a control server, which would keep count.

The program worked well – too well, in fact. Morris had known that if it traveled too fast there might be problems, but the limits he built in weren’t enough to keep the program from clogging up large sections of the internet, both copying itself to new machines and sending those pings back. When he realized what was happening, even his messages warning system administrators about the problem couldn’t get through.

Källa: 30 years ago, the world’s first cyberattack set the stage for modern cybersecurity challenges – CyberScoop