A fault injection attack deliberately disturbs hardware or software so it produces the wrong result, such as skipping a check or leaking secrets. Attackers may use voltage, clock, laser, or other disturbance methods against devices handling keys or authentication. Defenders monitor for tamper resistance, redundancy, and fault-detection controls.
How a Fault Injection Attack Disrupts Correct Execution
A fault injection attack works by disturbing the target at the right moment so a computation no longer follows its expected path. The attacker is not trying to “break” the system in a noisy way; they are trying to create a controlled error that changes a security decision, a cryptographic operation, or a validation step. That is why the attack is especially effective when timing is precise and the target lacks strong error handling.
In practice, the attacker aims for a narrow window in which the device is processing sensitive state such as keys, authentication logic, or checks that protect privileged actions. The disturbance can cause a skipped branch, altered instruction, corrupted memory read, or incorrect output. Even a single induced error can be enough if it lands on a check that was assumed to be reliable.
On the defensive side, the important point is that fault injection is both a reliability problem and a security problem. Controls such as redundancy, tamper resistance, invariant checks, error detection, and safe failure behavior matter because the attack succeeds when the system accepts corrupted results as valid.
Where Fault Injection Becomes a Security Break
Fault injection matters most when a small execution error can produce a large trust failure. If an authentication check is skipped, a signature verification is bypassed, or a key-handling routine returns the wrong value, the attacker may move from disturbance to unauthorized access or secret exposure. The attack often exploits the assumption that hardware and software will always execute exactly as designed.
Faults can be induced in several ways, including voltage manipulation, clock manipulation, laser or light-based disturbance, electromagnetic interference, and other physical or environmental techniques. The common thread is that the attacker is steering the target into an unstable state at a moment that benefits them.
That makes the subject closely related to secure cryptographic implementation. For a deeper refresher on the protection side of key handling and algorithm selection, see the Cryptography Basics Guide, which covers the surrounding controls that fault injection tries to undermine.
What Defenders Should Verify in Devices and Embedded Systems
Fault injection is most concerning where the attacker can touch the device, influence its environment, or repeatedly probe it until a fault lands. Devices that handle authentication, secure boot, signing operations, or secret storage should be assessed not only for normal functional correctness, but for how they behave when timing, power, or inputs are abnormal.
Defenders should treat “one wrong result” as a meaningful event if it occurs in a trust boundary. A single corrupted decision can expose a key, disable a control, or create a false success condition that the rest of the stack accepts. That is why well-designed systems combine fault detection with tamper response and use redundant checks where a single point of failure would be dangerous.
Attackers often pair disturbance with observation, so monitoring for abnormal resets, repeated failures, unexplained error states, or signs of physical tampering is part of the defense. For broader threat context on how attackers abuse compromised credentials and trusted execution paths, the State of NHI & AI Agent Breach Report 2026 shows how quickly access abuse escalates once trust material is exposed.
Risk and Threat Considerations
Fault injection is dangerous because the attacker does not need to defeat the whole control stack, only one critical moment. If the target is a device that protects secrets, signs code, or authorizes access, a successful fault can turn a defensive check into an attacker-controlled outcome.
Failure mechanism: The disturbance corrupts execution at a precise point, causing skipped checks, altered branches, or incorrect cryptographic or authentication results.
Impact: The device may accept unauthorized actions, reveal sensitive material, or produce outputs that downstream systems trust as valid.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
NIST SP 800-53 Rev 5 and OWASP ASVS set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| NIST SP 800-53 Rev 5 | SI-7 — Software, Firmware, and Information Integrity | Fault injection corrupts execution integrity and trusted decisions. |
| SC-39 — Process Isolation | Isolation limits the blast radius when one component is faulted. | |
| PE-3 — Physical Access Control | Physical proximity enables voltage, clock, and laser disturbance attacks. | |
| Recommendation — Add integrity checks that detect corruption and force safe failure on anomalous execution. Isolate security-critical processes so a fault in one component cannot bypass protections elsewhere. Restrict physical access to devices that protect secrets or make trust decisions. | ||
| OWASP ASVS | V11 — Cryptography | Fault injection often targets cryptographic operations and key handling. |
| V6 — Authentication | Faults can skip or corrupt authentication checks. | |
| Recommendation — Validate cryptographic routines and protect key operations against fault-induced bypasses. Ensure authentication logic fails closed when execution errors or abnormal states occur. | ||
Practitioner Guidance
What to verify: Test the highest-value code paths under abnormal timing, power, and reset conditions, especially where a single pass or fail decision protects keys, identity, or privileged functions.
Common mistake: Teams often validate only normal-case functionality and assume a passing test suite means the security boundary is robust. That assumption fails when the attack works by making the system misbehave only once.
What good looks like: The system detects the fault, fails closed, preserves evidence of the anomaly, and does not continue with a security-sensitive action when execution integrity is uncertain.
Practitioner takeaway: Treat fault injection as an integrity attack on trust decisions, not just a hardware nuisance, because the real risk is a single corrupted check becoming a full security bypass.
Related resources from NHI Mgmt Group
- What is the difference between prompt injection risk and identity abuse in agents?
- How should security teams use attack path analysis to prioritise resilience work?
- How do input and output guardrails work together to reduce prompt injection risk in production AI systems?
- How should security teams build recovery procedures for identity systems so they work during an outage or attack?