Definition
Analyzing the behavior of embedded code in firmware and looking for anomalous behavior and suspicious activity.
How it works
Firmware behavior analysis provides protections by ensuring that installed firmware has not been tampered with or modified. Firmware analysis applies to mutable firmware and immutable read-only memory (ROMs).
Firmware in deployed network devices is typically not analyzed and monitored for vulnerabilities and thus is subject to potential attacks. This technique makes use of known and measured behavioral attributes, including timing attributes, of analyzed firmware on deployed devices.
A behavioral method that employs known timing measurements may use the timing results from a challenge and response protocol to detect the presence of malware in embedded firmware. Firmware device timing measurements are made, specific to the installed device, and are used in the verifying function.
The original firmware image is modified by injecting a monitoring software component into the embedded firmware code. The injected software components will allow for a software root of trust, the challenge and response protocol, to be implement in the firmware.
A challenge-response is issued and includes a nonce so that replays are not allowed. The firmware will calculate a checksum over all of memory, including the nonce, and return the result. The verification system will compare the computed checksum and the time it took for the computation of the checksum to determine if the firmware has been modified.
Considerations
- The firmware code will need to be modified to include the behavioral monitoring functionality.
- This technique is sensitive to the device the embedded firmware is hosted on and it is expected that the devices and firmware will need to be profiled and analyzed to determine timing estimation.
- This technique is not expected to be one hundred percent correct as you would expect in a hardware root of trust solution and may require some tuning.
Implementation perspective
Firmware Behavior Analysis should be treated as a technical defensive capability rather than a product checkbox. In practice, teams should define the protected scope, the conditions under which the technique acts, and the observable evidence that demonstrates the intended behavior. For this technique, likely engineering context includes Firmware.
Use the technique to identify suspicious, unauthorized, or abnormal activity through observable evidence and repeatable analysis.
Questions to ask
- Which events, states, or artifacts must be observed for the analysis to work?
- What analytic logic, threshold, comparison, or signature turns observations into a finding?
- How are expected false positives, blind spots, and environmental variations documented?
- Who receives the result, and what action is expected when the technique produces a finding?
Evidence and validation
- Telemetry and data-source configuration records
- Analytic logic, thresholds, signatures, and version history
- Test cases demonstrating expected positive and negative results
- Alert, triage, escalation, and tuning records
Common failure patterns
- Required telemetry is missing, delayed, or transformed in a way that invalidates the analysis.
- The technique produces alerts without an accountable triage and response process.
- Detection coverage is claimed from product deployment without testing the relevant analytic behavior.
This implementation perspective is original Bare Metal Cyber educational content. It does not replace the official D3FEND definition or establish that a specific product implements the technique.
Technique hierarchy
Top-level family
Parent techniques
Direct child techniques
None listed at this level.
Artifacts and ontology entities
These relationships describe how D3FEND connects a defensive technique to artifacts or other ontology entities. They describe graph semantics, not a product certification.
Explicit technique relationships
Show inferred artifact relationship paths (1)
Offensive-technique relationships
These relationships are generated from D3FEND graph paths and are explicitly experimental. They should be treated as hypotheses for defensive analysis—not as proof that the technique prevents, detects, or removes an offensive behavior.
ATT&CK Enterprise (4)
ATT&CK for ICS (2)
Authoritative sources
- Open this technique on the official D3FEND website ↗
- Open the official ontology resources ↗
- ConFirm: Detecting Firmware Modifications in Embedded Systems using Hardware Performance Counters ↗Department of Electrical and Computer Engineering, Polytechnic School of Engineering, New York University and Department of Electrical and Computer Engineering, New York University Abu Dhabi · Xueyang Wang, Charalambos Konstantinou, Michail Maniatakos, Ramesh Karri · AcademicPaperReference
- VIPER: Verifying the Integrity of PERipherals' Firmware ↗CyLab, Carnegie Mellon University · Yanlin Li, Jonathan M. McCune, Adrian Perrig · AcademicPaperReference
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