Botnets are responsible for many large scale attacks happening on the Internet. Their weak point, which is usually targeted to take down a botnet, is the command and control infrastructure: the foundation for the diffusion of the botmaster's instructions. Hence, botmasters employ stealthy communication methods to remain hidden and retain control of the botnet. Recent research has shown that blockchains can be leveraged for under the radar communication with bots, however these methods incur fees for transaction broadcasting. This paper discusses the use of a novel technology, Whisper, for command and control instruction dissemination. Whisper allows a botmaster to control bots at virtually zero cost, while providing a peer-to-peer communication infrastructure, as well as privacy and encryption as part of its dark communication strategy. It is therefore well suited for bidirectional botnet command and control operations, and creating a botnet that is very difficult to take down.
