The essential guide to ISO 27001
Summary

How many times have you seen the ISO 27001 badge on an IT company website? Of course, you might intuitively understand that a certified company projects an image of trust, but you might not know what the certification exactly means. Let’s dive into the ISO 27001 core principles and certification process. 

What is ISO 27001?

The goal of this certification is to:

This standard is technology-agnostic and vendor-neutral, making it adaptable across various industries and sizes of organizations.

How can you achieve compliance with ISO 27001?

To be compliant with ISO 27001, you must be compliant with the following mandatory clauses:

1. Context of the Organization

Objectives:

Understand internal and external issues, identify stakeholders and their expectations, and define the scope of the ISMS.

2. Leadership

Objectives:

Top management must demonstrate leadership and commitment. Define a security policy. Assign roles and responsibilities.

3. Planning

Objectives:

Perform risk assessments. Identify information security risks and opportunities. Develop risk treatment plans.

4. Support

Objectives:

Ensure resources, awareness, competence, and communication. Manage documented information (policies, procedures, evidence).

5. Operation

Objectives:

Implement and control the ISMS processes. Carry out risk treatment plans. Manage changes and assess the effectiveness of controls.

6. Performance Evaluation

Objectives:

Monitor, measure, analyze, and evaluate ISMS performance. Conduct internal audits. Perform management reviews.

7. Improvement

Objectives:

Address nonconformities and implement corrective actions. Support a culture of continuous improvement.
Applying relevant controls from Annex A

Annex A of ISO 27001 lists 93 security controls (as of the 2022 update), categorized into 4 themes:

These are aligned with the outcomes of your risk assessment and are not all mandatory—you choose based on your threat model and justification. 

Documentation Requirements

You need to document everything when you want to achieve compliance with ISO 27001. But what do these documents look like? Typical documents include:

  • Information security policy

  • Statement of Applicability (SoA)

  • Risk assessment & treatment methodology

  • Risk treatment plan

  • Evidence of monitoring, audits, and reviews.

The auditing process

After implementing all the previous steps, you will undergo an internal audit. You must conduct regular internal audits to ensure the ISMS meets the ISO standard.

If you aim for the formal certification, you must also undergo a certification audit. An accredited external auditor assesses compliance through a two-stage audit process:

  • Stage 1: Documentation review.

  • Stage 2: Implementation and effectiveness review.

Additional Resources

The following is a list of tools and frameworks that are often used alongside ISO 27001 to help you achieve the certification: 

  • NIST CSF SP 800-53 (as supplemental frameworks)

  • ISO 27002 (guidance on implementing controls)

  • Risk assessment tools like OCTAVE (Operationally Critical Threat, Asset and Vulnerability Evaluation) or FAIR
  • GRC platforms (e.g., Vanta, Drata, OneTrust)

Best tips for success

If you’re approaching ISO 27001 for the first time, here are some useful tips that will help you achieve the certification:

  1. Understand the ISMS scope early – define it clearly and consider your dependencies. 
  2. Perform a gap analysis first: go through the Annex A controls and identify what’s missing (classify them in Implemented, Not Implemented, and Partial). 
  3. Develop a risk methodology to identify assets, threats, vulnerabilities, and existing controls. Then, perform likelihood × impact scoring and decide on treatment options: Avoid, Reduce, Transfer, or Accept.
  4. Document what you do and do what you document. 
  5. Get executive buy-in and appoint a champion. Have top management assign an Information Security Officer (ISO) or equivalent. Appoint control owners in each department to drive implementation.
  6. Invest in awareness and training. Train employees on phishing, password hygiene, incident reporting, etc.
  7. Start internal audits early and use them to find weaknesses and train your staff.  
  8. Build an evidence repository: for each control or policy, keep proof – logs, screenshots, meeting minutes, Git commits, training records, etc.
  9. Leave enough time before certification: plan a 6–12 month timeline depending on your starting point. Auditors may return in 30–90 days if gaps are found.
  10. Embrace continuous improvement: the ISO 27001 cycle is based on PDCA (Plan–Do–Check–Act).

Good luck with your ISO 27001 certification! 

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