TA0005 · DEFENSE EVASION
Patch System Image
Adversaries may modify the operating system of a network device to introduce new capabilities or weaken existing defenses.
Detect it with
Compare the checksum of the operating system file with the checksum of a known good copy from a trusted source. Some embedded network device platforms may have the capability to calculate the checksum of the file, while others may not.
Why it matters on shift
Patch 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