In November 2018, Cisco Talos discovered an attack campaign, called DNSpionage, in which threat actors created a new remote administrative tool that supports HTTP and DNS communication with the attackers’ command and control(C2). Since then, there have been several other public reports of additional DNSpionage attacks, and in January, the U.S. Department of Homeland Security issued an alert warning users about this threat activity.

https://blog.talosintelligence.com/2019/04/dnspionage-brings-out-karkoff.html