ISO 27001 Annex A 8.27 Secure Systems Architecture and Engineering Principles

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What is ISO 27001 Annex A 8.27 Secure Systems Architecture and Engineering Principles?

ISO 27001 Annex A 8.27 Secure Systems Architecture and Engineering Principles is an ISO 27001 control that requires us to design security into all architecture layers in the development lifecycle. You may hear the term – ‘security by design and default’.


ISO 27001 Annex A 8.27 is a preventive control to ensure information systems are securely designed, implemented and operated within the development life cycle.


The ISO 27001 standard defines ISO 27001 Annex A 8.27 as:

Principles for engineering secure systems should be established, documented, maintained and applied to any information system development activities.

ISO27001:2022 Annex A 8.27 Secure Systems Architecture and Engineering Principles

Implementation Guide

Whilst I am a software engineering degree educated and time served professional, I am not in the business of telling you how to develop either systems or software. These are professions in their own right. Time has moved on. What I am going to do is show you want the ISO 27001 standard expects in the implementation for you to achieve ISO 27001 certification. These are on the whole, no brainers, common sense and what you would expect but let us take a look anyway.


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Security Engineering Principles

You are going to establish, document and apply information security principles and activities. This will be designed into all architecture layers such as the business, data, application, network and technology layers.

It will include:

  • Security Controls – the full range of controls required to protect against identified threats
  • Security Events – the capability of controls to protect from, respond to and detect security events
  • Business Process Specifics – controls required by particular business controls such as digital signature, encryption or integrity checking
  • Application – where the controls are applied
  • Integration – how the controls work together


The principles will take account of the need to integrate with a security architecture, technical architecture, capability of the organisation, costs, time, complexity and current good practices when agreeing the principles.


Secure system engineering techniques include

  • Security architecture principles such as – least privilege, security by default, security by design, defence in depth
  • Design reviews focussed on security
  • Documentation of controls
  • Documentation of controls that do not meet requirements
  • System Hardening
  • Tamper resistance
  • Segregation
  • Secure Virtualisation

Zero Trust

Zero Trust as a principle is something you will consider and demonstrate and examples are

  • Not relying only on network perimeter security
  • Using the phrase ‘never trust always verify’ for access to information
  • Encrypting information end to end
  • Not trusting anything inside or outside a network and treating it as if it came from an open and external network
  • Using least privilege for access control
  • Authenticating and validating requests for information systems, always, based on authentication information, user identities, data classification.
  • Enforcing strong / multi factor authentication

Third party developers

This control applies in equal measure to third party developers and should be enforced via contract or legally binding agreements and alignment between the third party and the outsourced developer should be in place.


Reviews should be in place to ensure controls and principles are appropriate and effective.

Secure Development Policy

If you are developing software then the first step is to create, or download, your secure development policy. The secure development policy set’s out what you do for information security in the context of software and systems development. It does not set out how you do it, as how you do it is covered in your processes.

The ISO 27001 Template is the quickest way to do this but you can also take a look and write it yourself.

ISO 27001 Secure Development Policy Template

For more detail on software development read –ISO 27001 Annex A 8.25 Secure Development Life Cycle. We cover it in more detail in that guide.


This control is very specific to those that do development and is a very technical control. You will require the input of specialist technical resources across multiple, relevant domains. The advice is to document everything.

ISO 27001:2022 requirements

Organisational Controls - A5

ISO 27001 Annex A 5.1 Policies for information security

ISO 27001 Annex A 5.2 Information Security Roles and Responsibilities

ISO 27001 Annex A 5.3 Segregation of duties

ISO 27001 Annex A 5.4 Management responsibilities

ISO 27001 Annex A 5.5 Contact with authorities

ISO 27001 Annex A 5.6 Contact with special interest groups

ISO 27001 Annex A 5.7 Threat intelligence – new

ISO 27001 Annex A 5.8 Information security in project management

ISO 27001 Annex A 5.9 Inventory of information and other associated assets – change

ISO 27001 Annex A 5.10 Acceptable use of information and other associated assets – change

ISO 27001 Annex A 5.11 Return of assets

ISO 27001 Annex A 5.11 Return of assets

ISO 27001 Annex A 5.13 Labelling of information

ISO 27001 Annex A 5.14 Information transfer

ISO 27001 Annex A 5.15 Access control

ISO 27001 Annex A 5.16 Identity management

ISO 27001 Annex A 5.17 Authentication information – new

ISO 27001 Annex A 5.18 Access rights – change

ISO 27001 Annex A 5.19 Information security in supplier relationships

ISO 27001 Annex A 5.20 Addressing information security within supplier agreements

ISO 27001 Annex A 5.21 Managing information security in the ICT supply chain – new

ISO 27001 Annex A 5.22 Monitoring, review and change management of supplier services – change

ISO 27001 Annex A 5.23 Information security for use of cloud services – new

ISO 27001 Annex A 5.24 Information security incident management planning and preparation – change

ISO 27001 Annex A 5.25 Assessment and decision on information security events 

ISO 27001 Annex A 5.26 Response to information security incidents

ISO 27001 Annex A 5.27 Learning from information security incidents

ISO 27001 Annex A 5.28 Collection of evidence

ISO 27001 Annex A 5.29 Information security during disruption – change

ISO 27001 Annex A 5.31 Identification of legal, statutory, regulatory and contractual requirements

ISO 27001 Annex A 5.32 Intellectual property rights

ISO 27001 Annex A 5.33 Protection of records

ISO 27001 Annex A 5.34 Privacy and protection of PII

ISO 27001 Annex A 5.35 Independent review of information security

ISO 27001 Annex A 5.36 Compliance with policies and standards for information security

ISO 27001 Annex A 5.37 Documented operating procedures 

Technology Controls - A8

ISO 27001 Annex A 8.1 User Endpoint Devices

ISO 27001 Annex A 8.2 Privileged Access Rights

ISO 27001 Annex A 8.3 Information Access Restriction

ISO 27001 Annex A 8.4 Access To Source Code

ISO 27001 Annex A 8.5 Secure Authentication

ISO 27001 Annex A 8.6 Capacity Management

ISO 27001 Annex A 8.7 Protection Against Malware

ISO 27001 Annex A 8.8 Management of Technical Vulnerabilities

ISO 27001 Annex A 8.9 Configuration Management 

ISO 27001 Annex A 8.10 Information Deletion

ISO 27001 Annex A 8.11 Data Masking

ISO 27001 Annex A 8.12 Data Leakage Prevention

ISO 27001 Annex A 8.13 Information Backup

ISO 27001 Annex A 8.14 Redundancy of Information Processing Facilities

ISO 27001 Annex A 8.15 Logging

ISO 27001 Annex A 8.16 Monitoring Activities

ISO 27001 Annex A 8.17 Clock Synchronisation

ISO 27001 Annex A 8.18 Use of Privileged Utility Programs

ISO 27001 Annex A 8.19 Installation of Software on Operational Systems

ISO 27001 Annex A 8.20 Network Security

ISO 27001 Annex A 8.21 Security of Network Services

ISO 27001 Annex A 8.22 Segregation of Networks

ISO 27001 Annex A 8.23 Web Filtering

ISO 27001 Annex A 8.24 Use of CryptographyISO27001 Annex A 8.25 Secure Development Life Cycle

ISO 27001 Annex A 8.26 Application Security Requirements

ISO 27001 Annex A 8.27 Secure Systems Architecture and Engineering Principles

ISO 27001 Annex A 8.28 Secure Coding

ISO 27001 Annex A 8.29 Security Testing in Development and Acceptance

ISO 27001 Annex A 8.30 Outsourced Development

ISO 27001 Annex A 8.31 Separation of Development, Test and Production Environments

ISO 27001 Annex A 8.32 Change Management

ISO 27001 Annex A 8.33 Test Information

ISO 27001 Annex A 8.34 Protection of information systems during audit testing