Many families of malware (such as those used in APTs), as well as botnets used for DDoS attacks, periodically contact their Command & Control server (C2) in order to receive instructions, downloads of updated code, or to exfiltrate stolen data. C2 servers can also be used to provide attackers remote access to a compromised system. …
Article Link: https://dwaterson.com/2019/07/29/malware-c2-communication-using-domain-generation-algorithms/