Currently, there are fifty-seven (57) standards, guidelines and other documents in the ISO 27000 Family on information security

The total number is regularly changing with the occasional withdrawal of some standards and the regular addition of others (several drafts of new standards have not been included here). How then is one to know which ones are mandatory and which are guidelines/advisory?  The answer to this question has evolved from our research for ISO 27001 courses and can be found below.

8 types of Standards in the ISO 27001 Series

The first step towards understanding the ISO 27001 series of standards is to divide them by type.  The 8 types and their application are as follows:

1. Requirements

These Standards, such as ISO  27001, set out the requirements that must be fulfilled in order to achieve compliance with the Standard.  Evidence of such compliance is gathered and recorded by Certification Bodies as the basis of their issuing Certifications of Compliance.

2. Information Only

Standards here, such as ISO 27000, define the terms and definitions and explain the concepts associated with Information Security. They are advisory by their nature and do not constitute requirements.

3. Code of Practice

A code of practice is a document that complements a requirements standard so as to provide detailed practical guidance on how to comply with those requirements.  While not itself constituting a set of requirements, the Code should be followed unless another solution with the same or better outcome is in place.

4. General Guidelines

For a given topic or situation these provide detailed practical guidance on how to comply with requirements.  Again, they do not constitute requirements but do generate an expectation that, if they are applicable to the given circumstances, they will be applied.

5. Sector-specific Guidelines

For sectors with particular requirements regarding information security, e.g. telecommunications organizations, these provide detailed practical guidance on how to comply with requirements.

They also identify additional vulnerabilities associated with the sector and identify controls to address the threats arising.  They do not constitute requirements but do generate an expectation that, if they are applicable to the given circumstances, they will be applied.

6. Control-specific Guidelines

For assets with particular vulnerabilities or circumstances regarding information security, e.g. network security and software application security, these guidelines provide detailed practical guidance on how to meet the requirements. 

Again, they do not constitute requirements but do generate an expectation that, where applicable, they will be applied.

7. Technical Report

A technical discussion document on a topic of interest and/or relevance.

8. Technical Specification

A set of requirements that are advisory in nature, i.e. they do not constitute formal requirements.

Differences Among the ISO 27000 Series of Documents

Standards other than requirements standards offer non-mandatory guidance and establish concepts and definitions that help in establishing and maintaining effective information security systems. 

Such documents are used by external auditors to direct their evidence gathering and to provide a logical basis for their findings.

In circumstances where they might have been followed but were not, you can expect auditors to challenge you to demonstrate how by alternative means a corresponding level of control and security is being achieved.

Is Compliance with Other Standards and Guides in the ISO 27000 Series Mandatory?

Analysis by Type of the ISO 27000 Series of Standard

Based on the eight types of standards, we have analyzed all 56 documents.  A color-coded legend, shown below, was used in developing the Table of Standards.

Legend for Information Security Standard Type

Breakdown of ISO 27000 Standards with Description and Comments 

While the table is 11 pages long, it can be quickly reviewed to establish a comprehensive list of all the Standards that may apply to your circumstances.  Enjoy!

This is a Sample Page: Click the button to download a complete copy of the 11-page Table.

What of the Future?

As mentioned above, several new Standards in the series are at the draft stage.  We will monitor progress and, as new Standards are added, we will update the table above and advise our Subscribers interested in ISMS and ISO 27001 of these developments.

Note; Originally published in Dec 2019; revised and updated in July 2023.

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