Adversaries may steal data by exfiltrating it over a different protocol than that of the existing command and control channel. The data may also be sent to an alternate network location from the main command and control server.
Alternate protocols include FTP, SMTP, HTTP/S, DNS, SMB, or any other network protocol not being used as the main command and control channel. Different protocol channels could also include Web services such as cloud storage. Adversaries may opt to also encrypt and/or obfuscate these alternate channels.
This type of attack technique cannot be easily mitigated with preventive controls since it is based on the abuse of system features.
Exfiltration Over Alternative Protocols can be difficult to detect, and therefore enterprises may be better served focusing on detection at other stages of adversarial behavior.