Evgeniy Bogachev

GameOver Zeus was a peer-to-peer variant of the Zeus banking malware that drained accounts through hijacked browser sessions; the FBI put losses at more than $100 million. The same botnet distributed the Cryptolocker ransomware. In June 2014 an international effort, Operation Tovar, took down the infrastructure and U.S. charges were unsealed.

The $3 million reward followed in 2015. It has never been paid: Bogachev lives openly in Russia, which does not extradite its citizens, and U.S. officials have said Russian intelligence took an interest in the botnet's victims. He was named in U.S. sanctions in December 2016.