FR 3 — System Integrity (SI)

    IEC 62443 FR 3 — System Integrity (SI): how QuantLayer detects and prevents unauthorized modifications with OT-safe enforcement and audit-ready evidence.

    IEC 62443
    FR 3
    OT/ICS
    6 min
    Last updated: 2026-01-22

    Overview

    Protect systems from unauthorized modification and detect integrity compromise (tamper, drift, malicious changes).

    QuantLayer control mapping

    • Secure boot / measured boot evidence collection
    • Configuration and policy drift detection with alerts
    • Immutable logging of changes and remediation actions
    • Quarantine workflows when integrity is violated

    Implementation steps

    • Scope by zone: identify where this FR is most critical (e.g., safety zone, engineering access, remote vendor conduit).
    • Start in observe mode: baseline behavior and identify necessary exceptions.
    • Enforce gradually: enable controls in phases aligned to maintenance windows; document exceptions.
    • Continuously verify: monitor drift and anomalies; automate response where safe.

    Evidence checklist

    • Integrity check results and drift events
    • Change history (who/what/when) with signed artifacts
    • Containment and remediation records
    Implementation note
    IEC 62443 compliance is achieved through a combination of people, process, and technology controls. QuantLayer helps you operationalize the technical controls (identity, segmentation, integrity, telemetry, response) while producing audit-ready evidence to support your CSMS and assurance activities.