Security experts theorize that the takedown of the Rustock botnet has left a deep pit in the supply of compromised computers and that bot operators are scrambling to build bigger botnets. One out of every 169 emails carried a malicious link or attachment, an increase of 24 percent since March. Microsoft, the U.S. Federal Marshal service and security firm FireEye took down the botnet, a network of a million compromised computers. On Thursday, the company noted a 71 percent increase in zombies since March on Thursday.”]
Source: https://www.csoonline.com/article/2128148/after-rustock–botnet-rebuilding-underway.html