Sven Jaschan
German teenager who wrote both Netsky and Sasser in 2004, and whose case was cracked by Microsoft's reward money rather than by forensics.
Netsky spread as an email attachment and, among other things, removed rival worms such as MyDoom and Bagle, turning spring 2004 into something of a virus writers' war. Sasser arrived in May and needed no user at all: it exploited a buffer overflow in the Windows LSASS service that Microsoft had patched weeks earlier. Infected machines kept rebooting themselves, at airlines, banks and government agencies.
Microsoft had put up a $250,000 bounty, and tips from acquaintances led police to Jaschan in Rotenburg, Lower Saxony. He was 17 when he wrote the code and in 2005 received a suspended juvenile sentence. A security company hired him shortly afterwards.