TA0011 · COMMAND AND CONTROL
External Proxy
Adversaries may use an external proxy to act as an intermediary for network communications to a command and control server to avoid direct connections to their infrastructure.
Detect it with
Analyze network data for uncommon data flows, such as a client sending significantly more data than it receives from an external 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
External Proxy 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