ISO 27001 Secure Coding Explained

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Last updated Jul 5, 2025

Author: Stuart Barker | ISO 27001 Lead Auditor

ISO 27001 Secure Coding Explained with examples and ISO 27001 templates. Everything you need to know for ISO 27001 certification.

ISO 27001 Secure Coding

Secure Coding focuses on building security directly into the software development process. Furthermore, it emphasises the importance of integrating security considerations directly into the software development process. This aligns with the concept of “security by design and default,” where security is built into the software from the ground up, rather than being an afterthought.

This proactive approach aims to prevent security vulnerabilities by ensuring secure software development practices.

It includes activities such as:

  • Code reviews: Regularly reviewing code for security vulnerabilities.
  • Threat modelling: Identifying and addressing potential security threats during the design and development phases.
  • Secure coding standards: Adhering to established secure coding guidelines and standards.
  • Developer training: Educating developers on secure coding principles and techniques.

Who owns it?

The Chief Information Security Officer (CISO), supported by software development specialists, is responsible for identifying, approving, and implementing information security requirements for secure coding.

ISO 27001 Toolkit Business Edition
ISO 27001:2022 Toolkit
ISO 27001 Toolkit Consultant Edition
ISO 27001:2022 Toolkit Consultant Edition

How to implement ISO 27001 Secure Coding

The following is compliance guidance for secure coding.

Time needed: 1 hour and 30 minutes

How to implement ISO 27001 Secure Coding

  1. Establish a Secure Coding Framework

    Define and implement organisation-wide secure coding standards and guidelines.
    Establish a minimum security baseline for all software development activities.
    Extend these practices to cover third-party components and open-source software.

  2. Implement Continuous Improvement

    Continuously monitor emerging threats and vulnerabilities.
    Regularly review and update secure coding principles based on new information and best practices.

  3. Before Coding

    Define clear expectations and approved principles for secure coding.
    Analyse historical coding practices and common vulnerabilities.
    Configure development tools (e.g., IDEs) to support secure coding practices.
    Ensure developers are qualified and trained in secure coding techniques.
    Incorporate secure design and architecture principles, including threat modelling.

  4. During Coding

    Utilise secure coding practices specific to the programming languages being used.
    Employ techniques like pair programming, code reviews, and test-driven development.
    Adhere to structured programming principles.
    Document code thoroughly and address identified defects promptly.
    Prohibit the use of insecure design techniques (e.g., hard-coded passwords).

  5. After Coding

    Conduct thorough security testing throughout the development and testing phases.
    Securely package and deploy software applications.

  6. Manage Vulnerabilities

    Respond to reported vulnerabilities effectively (see 8.8).
    Monitor logs for errors and suspected attacks to identify and address issues.
    Protect source code from unauthorised access and tampering.

  7. Using External Components

    Manage external libraries effectively (e.g., maintain an inventory and ensure timely updates).
    Select and utilise well-vetted components, especially for critical functions like authentication and cryptography.
    Consider the license, security history, and long-term availability of external components.

  8. Modifying Software Packages

    Carefully consider the potential risks
    Assess the impact of modifications on the integrity of built-in security controls.
    Obtain vendor consent when necessary.
    Evaluate the potential for obtaining required changes through standard program updates.
    Determine the impact of potential future maintenance responsibilities.
    Ensure compatibility with other software systems.

Supplementary Guidance

1. Secure Code Execution

Tamper Resistance: Ensure that security-relevant code is executed as intended and cannot be easily modified or compromised.

Secure Execution Environments: For interpreted languages, restrict code execution to secure environments (e.g., servers with limited user access, cloud services with strong access controls) to minimise the risk of unauthorised access and modification.

Strong Authentication: Implement robust authentication and authorisation mechanisms for administrative access to secure environments.

2. Assume a Breach

Design applications under the assumption that they are always subject to attack, whether intentional or unintentional.
Implement fault tolerance mechanisms to minimise the impact of potential errors or attacks.

3. Prevent Common Vulnerabilities

Address common web application vulnerabilities like SQL injection and cross-site scripting through secure design and coding practices.

ISO 27001 Secure Development Policy Template

The following is a fully ISO 27001 compliant ISO 27001 Secure Development Policy Template.

ISO 27001 Secure Development Policy Template

External Guidance

Refer to the ISO/IEC 15408 series for further guidance on information and communication technology (ICT) security evaluation.

Further Reading

ISO 27001 Annex A 8.28 Secure Coding

ISO 27001 Secure Development Policy Template

ISO27001 Annex A 8.25 Secure Development Life Cycle

ISO27001 Annex A 8.26 Application Security Requirements

ISO27001 Annex A 8.27 Secure Systems Architecture and Engineering Principles

ISO27001 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 27001:2022 requirements

ISO 27001 Clauses

ISO 27001 Clause 4.1 – Understanding The Organisation And Its Context

ISO 27001 Clause 4.2 – Understanding The Needs And Expectations of Interested Parties

ISO 27001 Clause 4.3 – Determining The Scope Of The Information Security Management System

ISO 27001 Clause 4.4 – Information Security Management System

ISO 27001 Clause 5.1 – Leadership and Commitment

ISO 27001 Clause 5.3 – Organisational Roles, Responsibilities and Authorities

ISO 27001 Clause 6.1.1 – Planning General

ISO 27001 Clause 6.1.2 – Information Security Risk Assessment

ISO 27001 Clause 6.1.3 – Information Security Risk Treatment

ISO 27001 Clause 6.2 – Information Security Objectives and Planning to Achieve Them

ISO 27001 Clause 6.3 – Planning Of Changes

ISO 27001 Clause 7.1 – Resources

ISO 27001 Clause 7.2 – Competence

ISO 27001 Clause 7.3 – Awareness

ISO 27001 Clause 7.4 – Communication

ISO 27001 Clause 7.5.1 – Documented Information

ISO 27001 Clause 7.5.2 – Creating and Updating Documented Information

ISO 27001 Clause 8.3 – Information Security Risk Treatment

ISO 27001 Clause 9.1 – Monitoring, Measurement, Analysis, Evaluation

ISO 27001 Clause 9.2 – Internal Audit

ISO 27001 Clause 9.3 – Management Review

ISO 27001 Clause 10.1 – Continual Improvement

ISO 27001 Clause 10.2 – Nonconformity and Corrective Action

ISO 27001 Organisation Controls

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

ISO 27001 Annex A 5.8: Information security in project management

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

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

ISO 27001 Annex A 5.11: Return of assets

ISO 27001 Annex A 5.12: Classification of information

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

ISO 27001 Annex A 5.18: Access rights

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

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

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

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

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

ISO 27001 Annex A 5.30: ICT readiness for business continuity

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

ISO 27001 Technical Controls

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 Cryptography

ISO 27001 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