TA0005 · DEFENSE EVASION
Impair Command History Logging
Adversaries may impair command history logging to hide commands they run on a compromised system. Various command interpreters keep track of the commands users type in their terminal so that users can retrace what they've done.
Detect it with
Correlating a user session with a distinct lack of new commands in their .bash_history can be a clue to suspicious behavior. Additionally, users checking or changing their HISTCONTROL , HISTFILE , or HISTFILESIZE environment variables may be suspicious.
Why it matters on shift
Impair Command History Logging is one of the concrete ways adversaries achieve defense evasion. 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 defense evasion, the next tactic is usually Credential Access. Search your telemetry for the transition before closing the ticket.
Kill-chain context