Study of DNS Based On the Command and Control

Attackers, in particular botnet controllers, use secret messaging systems to set up large-scale command and control. In order to systematically understand the potential capability of attackers, we investigate the practicable of using domain name service (DNS) as a stealthy botnet command-and-control channel. We explain and quantitatively analyze several techniques that can be used to effectively hide malicious DNS activities at the network level. Our experimental result makes use of a two-month-long 4.8GB campus network dataset and 1 million domain names obtained from alexa.com. We conclude that the DNS-based secret command-and-control channel (in particular the code word mode) can be very powerful for attackers, showing the requirement for further research by defenders in this direction. The resulting statistical analysis of DNS payload as a countermeasure has practical limitations inhibiting its large-scale deployment.