Threatpost reports that machines infected with the Rustock-related malware are now less than half the size that it was before the takedown in March.

The Rustock botnet was a huge player in the global spam and cybercrime machine, and researchers reported a precipitous drop in spam levels after the takedown. That drop was temporary, but the more lasting effect of the Rustock takedown was the disinfection of a huge number of the PCs that previously had been part of the botnet.

In the three months following the takedown, Microsoft officials found that the number of unique machines connecting to the control server for Rustock that the company has sinkholed dropped by more than 56 percent. India still has the highest number of infected PCs and the United States moved up from number four on that list in March, to number two in June.

  Microsoft Says Rustock Botnet Cut in Half