TA0005 · DEFENSE EVASION
Downgrade System Image
Adversaries may install an older version of the operating system of a network device to weaken security. Older operating system versions on network devices often have weaker encryption ciphers and, in general, fewer/less updated defensive features.
Detect it with
Many embedded network devices provide a command to print the version of the currently running operating system. Use this command to query the operating system for its version number and compare it to what is expected for the device in question.
Why it matters on shift
Downgrade System Image 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