Modify System Image
Where this stands
No Sigma rule can address this — the telemetry MITRE names has no Sigma logsource behind it.
None of MITRE's analytics for this technique name a log source that maps to a Sigma logsource — they describe abstract data ("Process::None"), API-hook telemetry, or prose channels with no reliable field names behind them.
What the technique is
Adversaries may make changes to the operating system of embedded network devices to weaken defenses and provide new capabilities for themselves. On such devices, the operating systems are typically monolithic and most of the device functionality and capabilities are contained within a single file. To change the operating system, the adversary typically only needs to affect this one file, replacing or modifying it. This can either be done live in memory during system runtime for immediate effect, or in storage to implement the change on the next boot of the network device.
Read it on attack.mitre.orgWhat MITRE says you would watch
- AN0482
Defenders may observe adversary attempts to alter or replace a network device’s operating system image through anomalous CLI commands, unexpected firmware updates, integrity check failures, or mismatches in version and checksum validation. Suspicious behavior includes modification of image files on storage, OS version output inconsistent with baselines, unexpected reloads or reboots after image replacement, and changes to boot configuration that load non-standard system images.
Technique names and descriptions © MITRE ATT&CK®, CC BY 4.0. Not endorsed by MITRE.