It’s based on the Mirai code, but much more virulent:
While Mirai caused widespread outages, it impacted IP cameras and internet routers by simply exploiting their weak or default passwords. The latest botnet threat, known as alternately as IoT Troop or Reaper, has evolved that strategy, using actual software-hacking techniques to break into devices instead. It’s the difference between checking for open doors and actively picking locks—and it’s already enveloped devices on a million networks and counting.
It’s already infected a million IoT devices.
EDITED TO ADD (11/14): Brian Krebs on Reaper.