In 2001, a pair of Italian programmers wrote a program called Ettercap, a “comprehensive suite for man-in-the-middle attacks” — in other words, a set of tools for eavesdropping, sniffing passwords, and remotely manipulating someone’s computer. Ettercap was free, open source, and quickly became the weapon of choice for analysts testing the security of their networks as well as hackers who wanted to spy on people. One user called it “sort of the Swiss army knife” of this type of hacking.

Ettercap was so powerful that its authors, ALoR and NaGA, eventually got a call from the Milan police department. But the cops didn’t want to bust the programmers for enabling hacker attacks. They wanted to use Ettercap to spy on citizens. Specifically, they wanted ALoR and NaGA to write a Windows driver that would enable them to listen in to a target’s Skype calls.