In 1986, an astronomer spent 10 months tracking down a 75-cent computer time discrepancy, only to uncover a German hacker who was selling U.S. defense secrets to the KGB.
The astronomer was Clifford Stoll, then 36 years old and working at the Lawrence Berkeley National Laboratory in California. Stoll had been reassigned from pure astronomy work to manage computers when he noticed something odd: a 75-cent discrepancy in accounting records for computer time. Most people might have written it off as a minor clerical error, but Stoll’s scientific instincts told him to investigate.
Over the next ten months, Stoll meticulously traced the anomaly through the lab’s computer systems. What he discovered was far bigger than a billing error, it was a hacker from West Germany who had broken into U.S. computer networks. The intruder was not just snooping for fun; he was stealing classified military information and selling it to the KGB, the Soviet Union’s intelligence agency during the Cold War.
Stoll used creative methods to track the hacker. In one famous example, he set up “digital honey pots”, fake files filled with enticing but meaningless military data, to monitor the intruder’s activity. He also coordinated with the FBI, CIA, and even German authorities, though at first, few officials took him seriously. Eventually, his persistence paid off: authorities arrested Markus Hess, the hacker, in West Germany.
This case became one of the earliest and most famous examples of cyber-espionage. It highlighted how vulnerable computer systems had become in the digital age, especially with sensitive defense information stored online.
Stoll later documented the entire experience in his bestselling book, The Cuckoo’s Egg (1989), which remains a classic in both cybersecurity and true-crime literature. His story demonstrated how even a tiny irregularity, just 75 cents, could unravel a global espionage plot. It’s the small details.
Fun Fact: To keep himself awake during the long nights of hacker tracking, Stoll would run around the lab’s hallways balancing on the walls and juggling. His eccentric energy became just as famous as the investigation itself.