Between 1986 and 1989--at a time when computer security was an unexplored field--a West German named Marcus Hess and a number of other computer hackers took advantage of loopholes in computer systems to gain unauthorized access to sensitive information. Pioneers in computer espionage, they reportedly sold that information to Soviet officials.

In the late 1980s, Marcus Hess worked as a computer programmer for a small computer company in West Germany. He also belonged to a computer group known as the Chaos Computer Club, based in Hamburg, West Germany. As a member of Chaos, Hess and a number of other West German hackers became involved in a computer-based espionage ring. Hess--who was known as "the Hanover Hacker" (because he lived in Hanover, West Germany)--started with a telephone call from his home phone. By making a local computer modem call in Hanover, he tapped into a European data network called...