The base SRs state the required system capability. Nested REs add capability for higher security levels; the From SL label identifies the first SL column in Annex B where each enhancement applies.
Teaching note: These summaries paraphrase the standard for learning and are not normative text. Confirm each SR, RE and security-level mapping in
Annex B. Apply the common constraints in
Clause 4, including preservation of essential functions.
Purpose
Maintain the integrity of communications, software, information, sessions and security functions throughout control-system operation.
For an SL-C(SI) claim, implement the applicable base SRs and every enhancement selected by the target security level and risk assessment.
SR and RE summaries
SR 3.1 – Communication integrity
Summary: Protect communicated information from unauthorised modification.
RE(1) – Cryptographic integrity protection
From SL: 3+ · Annex B mapping
Summary: Use cryptographic mechanisms to detect changes to communications.
SR 3.2 – Malicious code protection
Summary: Detect, prevent and respond to malicious code using controls suitable for industrial systems.
RE(1) – Malicious code protection at entry and exit points
From SL: 2+ · Annex B mapping
Summary: Apply malicious-code controls where information enters or leaves the system.
RE(2) – Central management and reporting for malicious code protection
From SL: 3+ · Annex B mapping
Summary: Centrally manage protection and collect system-wide status and alerts.
SR 3.3 – Security functionality verification
Summary: Verify that security functions operate correctly and report failures.
RE(1) – Automated security functionality verification
From SL: 3+ · Annex B mapping
Summary: Automate verification of security functions and reporting of the results.
RE(2) – Security functionality verification during normal operation
From SL: 4+ · Annex B mapping
Summary: Perform verification without taking the control system out of normal operation.
SR 3.4 – Software and information integrity
Summary: Detect unauthorised changes to software and information.
RE(1) – Automated notification of integrity violations
From SL: 3+ · Annex B mapping
Summary: Automatically notify responsible personnel when an integrity violation is detected.
SR 3.5 – Input validation
Summary: Validate input syntax, length and range before data affects control logic or security decisions.
SR 3.6 – Deterministic output
Summary: Place outputs in a known safe state when normal processing cannot be completed.
SR 3.7 – Error handling
Summary: Handle errors without exposing sensitive details or undermining essential functions.
SR 3.8 – Session integrity
Summary: Protect sessions against hijacking, replay and identifier misuse.
RE(1) – Invalidation of session IDs after session termination
From SL: 3+ · Annex B mapping
Summary: Invalidate identifiers promptly when their sessions terminate.
RE(2) – Unique session ID generation
From SL: 3+ · Annex B mapping
Summary: Generate a unique identifier for each session.
RE(3) – Randomness of session IDs
From SL: 4+ · Annex B mapping
Summary: Use sufficient randomness to make session identifiers impractical to predict.
SR 3.9 – Protection of audit information
Summary: Protect audit records and audit tools against unauthorised access, modification and deletion.
RE(1) – Audit records on write-once media
From SL: 4+ · Annex B mapping
Summary: Store audit records on media that prevents later alteration.