A few days after the majority of the command-and-control servers belonging to one of the variants of the Pushdo botnet were taken offline, some researchers say that there are indications that portions of the botnet are back to their old tricks. Pushdo, like a lot of modern botnets, is not simply one monolithic network; it s split into several different pieces and almost certainly is not controlled by one person or group. The researchers at Last Line of Defense worked with hosting providers to take down 20 of the roughly 30 known C&C servers that the company was able to identify.
Source: https://threatpost.com/some-pushdo-variants-resuming-spam-operations-083010/74394/