scope:

General

This document establishes requirements and provides guidance for the development and management of effective computer security programmes for I&C programmable digital systems. Inherent to these requirements and guidance is the criterion that the power plant I&C programmable digital system security programme complies with the applicable country's requirements.

This document defines adequate measures for the prevention of, detection of and reaction to malicious acts by digital means (cyberattacks) on I&C programmable digital systems. This includes any unsafe situation, equipment damage or plant performance degradation that could result from such an act, such as:

- malicious modifications affecting system integrity;

- malicious interference with information, data or resources that could compromise the delivery of or performance of the required I&C programmable digital functions;

- malicious interference with information, data or resources that could compromise operator displays or lead to loss of management of I&C programmable digital systems;

- malicious changes to hardware, firmware or software at the programmable logic controller (PLC) level.

Human errors leading to violation of the security policy and/or easing the aforementioned malicious acts are also in the scope of this document.

This document describes a graded approach scheme for assets subject to digital compromise, based on their relevance to the overall plant safety, availability, and equipment protection.

Excluded from the scope of this document are considerations related to:

- non-malevolent actions and events such as accidental failures, human errors (except those impacting the performance of cybersecurity controls) and natural events. In particular, good practices for managing applications and data, including back-up and restoration related to accidental failure, are out of scope;

NOTE 1 Although such aspects are often covered by security programme in other normative contexts (e.g., in the ISO/IEC 27000 series or in the IEC 62443 series), this document is only focused on the protection against malicious acts by digital means (cyberattacks) on I&C programmable digital systems. The main reason is that in the nuclear generation domain, other standards and practices already cover accidental failures, unintentional human errors, natural events, etc. The focus of IEC 62645 is made to provide the maximum consistency and the minimum overlap with these other nuclear standards and practices.

- site physical security, room access control and site security surveillance systems. These systems, while not specifically addressed in this document, are to be covered by plant operating procedures and programmes;

NOTE 2 This exclusion does not deny that cybersecurity has clear dependencies on the security of the physical environment (e.g., physical protection, power delivery systems, heating/ventilation/air-conditioning systems (HVAC), etc.).

- the aspect of confidentiality of information about I&C digital programmable systems is out of the scope of this document (see 5.4.3.2.3).

Annex A provides a rationale for and comments about the scope, definition and the document's application, and in particular about the exclusions and limitations previously mentioned.

Standards such as ISO/IEC 27001 and ISO/IEC 27002 are not directly applicable to the cyber protection of nuclear I&C programmable digital systems. This is mainly due to the specificities of these systems, including the regulatory and safety requirements inherent to nuclear facilities. However, this document builds upon the valid high level principles and main concepts of ISO/IEC 27001:2013, adapts them and completes them to fit the nuclear context.

This document follows the general principles given in the IAEA reference manual NSS17.

Application

This document is limited to computer security of I&C programmable digital systems (including non-safety systems) used in a NPP as well as associated computer-based tools. This document is applicable to the parts of electrical power systems covered by IEC 63046 which rely on digital programmable technology.

NOTE 1 For the sake of simplicity, the terms "I&C programmable digital systems" in the text refer both to I&C and the parts of electrical power systems covered by IEC 63046 which rely on digital programmable technology.

This document is intended for use in evaluating or changing established NPP security programmes for I&C programmable digital systems, and in establishing new programmes. This document is applied to all NPP I&C programmable digital systems throughout the life cycles of these systems, as specified in this document. It may also be applicable to other types of nuclear facilities.

NOTE 2 The term NPP is understood in its "physical site" meaning, NPP I&C programmable digital systems including systems within the NPP buildings, but also systems in the nuclear plant switchyard, water treatment facilities, etc.

Framework

The requirements and recommendations of this document are structured along three main normative clauses.

Clause 5 deals with cybersecurity on the programme life-cycle level; its approach is completely consistent with ISO/IEC 27001:2013. It is based on its structure and content, which are when needed, adapted and completed to fit the nuclear context specificities. Annex C provides a clause-to-clause correspondence table between the IEC 62645 structure and the ISO/IEC 27001:2013 structure. When direct references to ISO/IEC 27001:2013 content are made, the following terminological substitutions are to be made:

- the terms "information security management system" used in the referenced ISO/IEC 27001:2013 content correspond to "I&C digital programmable system cybersecurity program" in this document (as defined in Clause 3);

NOTE 1 This document focuses on the part of the program, or the dedicated program, related to I&C. This can be part of a larger program at the corporate level, which is out of the scope of this document.

- the term "information security" used in the referenced ISO/IEC 27001:2013 content correspond to "cybersecurity" in this document (as defined in Clause 3);

- the terms "information security policy" used in the referenced ISO/IEC 27001:2013 content correspond to "I&C digital programmable system policy" in this document.

NOTE 2 Some subclauses of ISO/IEC 27001:2013 contain internal references to other subclauses of ISO/IEC 27001. When relevant, the references used in these subclauses are to be considered in the IEC 62645 context, however, they do not reference IEC 62645 subclauses. See Annex C for help in the correspondences.

The subclauses related to the graded approach and security categorization are organized in a similar way to IEC 61226.

Clause 6 deals with cybersecurity on a system life-cycle level. It is structured along the system life-cycle of IEC 61513, adapted to take into account specifics of cybersecurity.

Clause 7 deals with cybersecurity at the cybersecurity control level. It provides the high level principles of an approach consistent with ISO/IEC 27002:2013, further detailed in IEC 63096.

IEC 61513 addresses the concept of a safety life cycle for the total I&C system architecture, and a safety life cycle for the individual systems. As part of the overall framework, IEC 61513 calls for establishment of an overall security plan to specify the procedural and technical measures to be taken to protect the architecture of I&C systems from digital attacks that may jeopardize functions important to safety. The provisions of the overall security plan may differentiate between requirements for systems supporting category A, B or C functions, as defined in IEC 61226 and include the establishment of controls for electronic and physical access. This document provides more detailed requirements for the overall security plan, as called for in IEC 61513.

Additional requirements for software of systems supporting category A functions are provided in IEC 60880 and IEC 62566. Additional requirements for software of systems supporting category B and C functions are provided in IEC 62138.

This document also covers security requirements for I&C programmable digital systems which are not in the scope of IEC 61513, IEC 60880, IEC 62138 and IEC 62566 but have a potential impact on plant equipment, availability and performance.