TA0011 · COMMAND AND CONTROL
Fallback Channels
Adversaries may use fallback or alternate communication channels if the primary channel is compromised or inaccessible in order to maintain reliable command and control and to avoid data transfer thresholds.
Detect it with
Analyze network data for uncommon data flows (e.g., a client sending significantly more data than it receives from a server). Processes utilizing the network that do not normally have network communication or have never been seen before are suspicious.
Why it matters on shift
Fallback Channels is one of the concrete ways adversaries achieve command and control. Recognising it in telemetry lets you name the technique in your ticket and pivot to what came before and after.
What to look for next
After command and control, the next tactic is usually Exfiltration. Search your telemetry for the transition before closing the ticket.
Kill-chain context