Stakkato
A Swedish teenager who roamed supercomputing centres on two continents in 2004–2005 and walked off with Cisco's source code.
The handle belonged to Philip Gabriel Pettersson of Uppsala, who was 16 when it started. The technique was simple and devastating: trojaned SSH clients and servers harvested passwords on one machine, which were then used to log into the next. Because researchers share accounts across institutions, the break-ins spread through TeraGrid, US national labs, NASA, military sites and Swedish universities.
In 2004 part of the source code for Cisco's router operating system IOS was copied and later surfaced online. The US indicted him in 2009, but Sweden does not extradite its own citizens outside the EU, and the case over the Swedish intrusions was handled by a Swedish court. The episode remains a lesson in how little a password is worth when the same people log in everywhere.