Damballa discovered the botnet in March and has been tracking its communication with command-and-control servers around the world.

FORBES: Chinese Botnet Sells Point-And-Click Cyberattacks

Internet security firm FireEye has spotted some 450, 000 infected computers from the Srizbi botnet - alleged to account for as much as half of all the spam on Earth - trying to "phone home" and reach their command and control servers.

BBC: Spam on rise after brief reprieve