System Firmware
Where this stands
No Sigma rule can address this — the telemetry MITRE names has no Sigma logsource behind it.
Sigma has no logsource taxonomy for ICS. MITRE's telemetry here is operational historians and controller state, which no Sigma rule can address.
What the technique is
System firmware on modern assets is often designed with an update feature. Older device firmware may be factory installed and require special reprograming equipment. When available, the firmware update feature enables vendors to remotely patch bugs and perform upgrades. Device firmware updates are often delegated to the user and may be done using a software update package. It may also be possible to perform this task over the network. An adversary may exploit the firmware update feature on accessible devices to upload malicious or out-of-date firmware. Malicious modification of device firmware may provide an adversary with root access to a device, given firmware is one of the lowest programming abstraction layers.
Read it on attack.mitre.orgWhat MITRE says you would watch
- AN1864
Monitor for firmware changes which may be observable via operational alarms from devices. Monitor device application logs for firmware changes, although not all devices will produce such logs. Monitor firmware for unexpected changes. Asset management systems should be consulted to understand known-good firmware versions. Dump and inspect BIOS images on vulnerable systems and compare against known good images. Analyze differences to determine if malicious changes have occurred. Log attempts to read/write to BIOS and compare against known patching behavior. […]
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