The Kelihos peer-to-peer botnet was one of the largest and longest-operating cybercrime infrastructures in existence. Its origins can be traced back to the Storm Worm, a botnet that emerged in 2007 and was one of the earliest criminal malware infrastructures to leverage peer-to-peer technology. After the demise of Storm, it was replaced by another new botnet known as Waledac that also leveraged peer-to-peer communications. Waledac was taken over and neutralized by a group of researchers in September 20101. The first generation of Kelihos emerged in December that year, three months after its predecessor Waledac was dismantled.