Command-and-Control Servers

In the first six months of 2007, 4,622 bot command-and-control servers were identified. This is a 3% decrease from the previous period, when 4,746 command-and-control servers were identified. The decrease in command-and-control servers reflects a consolidation of bot networks observed in second half of 2006. During that period, the number of command-and-control servers decreased and the average size of bot networks increased.

Source: Symantec Internet Security Threat Report, Vol. XII