Kelihos botnet, which researchers at Kaspersky Lab and Microsoft disrupted last fall by sinkholing the control channel, has sprung back to life and is using only slightly different versions of the original malware and controller list. The rejuvenation of the botnet illustrates the difficulty of permanently disabling these networks and the perseverance of the attackers who count on them for their livelihood. Microsoft officials said in a statement that they re not ready to say yet whether KelihOS has reformed or whether this is perhaps a new botnet altogether.
Source: https://threatpost.com/kelihos-botnet-resurfaces-013112/76156/