In this ultimate how to implement guide to ISO 27001 Annex A 8.28 Secure Coding, you will learn directly from an ISO 27001 Lead Auditor:
Table of contents
- 1. Establish Mandated Coding Standards
- 2. Implement Pre-Commit Security Hooks
- 3. Enforce Input Validation Libraries
- 4. Automate Dependency Scanning (SCA)
- 5. Sanitise Output Data
- 6. Secure Error Handling
- 7. Mandate Peer Code Reviews
- 8. Encrypt Data at the Application Level
- 9. Disable Insecure Framework Features
- 10. Verify Through Static Analysis (SAST)
1. Establish Mandated Coding Standards
Control Requirement: A defined set of secure coding principles must be applied to all development projects.
Required Implementation Step: Formally adopt the OWASP Top 10 or CWE/SANS Top 25 as your baseline standard. Configure your IDE linters (e.g., ESLint, SonarLint) to enforce these rules locally on developer machines before code is even committed.
Minimum Requirement: Developers cannot push code that violates the defined linter configuration file.
2. Implement Pre-Commit Security Hooks
Control Requirement: Secure coding rules must be enforced technically, not just procedurally.
Required Implementation Step: Install pre-commit hooks (using tools like Husky or pre-commit) that scan for hardcoded secrets, API keys, and basic syntax vulnerabilities. This creates a hard gate that prevents insecure code from entering the version control system.
Minimum Requirement: A commit containing “API_KEY=” is rejected by the local git client.
3. Enforce Input Validation Libraries
Control Requirement: All external input must be validated to prevent injection attacks.
Required Implementation Step: Standardise on a strict input validation library for your framework (e.g., Joi for Node.js, Hibernate Validator for Java). Ban the use of raw input processing and require positive validation (allow-listing) for all form data and API parameters.
Minimum Requirement: No API endpoint accepts raw input without passing through a validation schema.
4. Automate Dependency Scanning (SCA)
Control Requirement: Third-party libraries must be secure and free from known vulnerabilities.
Required Implementation Step: Integrate Software Composition Analysis (SCA) tools (like OWASP Dependency-Check or Snyk) into your CI/CD pipeline. Configure the build to fail automatically if any library with a CVSS score of 7.0 or higher is detected.
Minimum Requirement: You cannot deploy a build containing a “Critical” severity vulnerability in a dependency.
5. Sanitise Output Data
Control Requirement: Output must be encoded to prevent Cross-Site Scripting (XSS).
Required Implementation Step: Configure your templating engine (e.g., React, Thymeleaf) to auto-escape all variables by default. Manually audit any instance where developers use “dangerouslySetInnerHTML” or equivalent bypass methods to ensure strict sanitisation is applied.
Minimum Requirement: Context-aware encoding is applied to all user-generated content displayed in the browser.
6. Secure Error Handling
Control Requirement: Error messages must not reveal sensitive system information.
Required Implementation Step: Configure global error handlers to strip stack traces, database schema details, and server versions from HTTP responses returned to the client. Log the full details internally to a secure SIEM, but show the user a generic “An error occurred” message.
Minimum Requirement: API responses never return a 500 error containing a stack trace.
7. Mandate Peer Code Reviews
Control Requirement: Code changes must be reviewed by a qualified peer prior to merging.
Required Implementation Step: Configure your repository (GitHub/GitLab) branch protection rules to require at least one approval from a designated code owner. The reviewer must specifically check for security logic flaws that automated tools miss.
Minimum Requirement: No code is merged to the ‘Main’ branch without a documented peer approval.
8. Encrypt Data at the Application Level
Control Requirement: Sensitive data must be protected by the application logic.
Required Implementation Step: Identify sensitive fields (PII, financial data) and implement application-level encryption before writing to the database. Ensure keys are managed via a Key Management Service (KMS) and never stored in the application config files.
Minimum Requirement: Database administrators cannot read clear-text credit card numbers or passwords.
9. Disable Insecure Framework Features
Control Requirement: The development framework itself must be configured securely.
Required Implementation Step: Review the default settings of your framework (Django, Rails, Express). Explicitly disable debug mode in production, remove default welcome pages, and set secure HTTP headers (HSTS, CSP, X-Frame-Options) in the application middleware.
Minimum Requirement: Production headers score an ‘A’ on securityheaders.com.
10. Verify Through Static Analysis (SAST)
Control Requirement: Code must be scanned for security flaws before deployment.
Required Implementation Step: Embed a Static Application Security Testing (SAST) tool into the build pipeline. Ensure it scans the entire codebase on every pull request and blocks the merge if high-severity security hotspots are found.
Minimum Requirement: A clean SAST report is a prerequisite for every release candidate.
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