BS7799, ISO 27001 and ISO 17799

Uncategorized 2017-09-21

ISO 17799

Initially developed from BS7799-1, ISO 17799 is an international standard that sets out the requirements of good practice for Information Security Management.

ISO 27001

ISO 27001 defines the specification for an Information Security Management System (ISMS). It was developed from BS 7799 Part 2:2002. The scope of any ISMS includes people, processes, IT systems and policies. This web site gives an overview of the stages involved and includes the changes made in ISO 27701 (based on the revised BS 7799 Part 2, issued in September 2002).


The latest versions of BS7799 is BS7799-3, Guidelines for Information Security Risk Management. It support ISO 27001 and covers the main aspects fo risk assessment.


The following pages should be read in order:

  • The ISO 17799 Cycle
  • Plan Do Check Act
  • Conclusions

Using a combination of both diagrams and text, these pages explain the process associated with adopting the standard.


The full cycle, from consideration of the standard’s merits through to actual implementation, is depicted in figure 1 below.

Figure 1: The ISO 17799 cycle

The cycle depicted in figure 1 (above) outlines the typical stages that would be followed when adopting ISO 17799 as an internal standard. These stages are detailed in the points below:

  • The merits of the standard are considered, such as enhancing the security of the organisation, as well as the confidence of new/existing customers and business partners.
  • A decision is made to implement ISO 17799. It may be the case that the organisation wishes to simply become compliant by adhering to the standard, or it may mean that certification is sought.
  • Resources in terms of people and time are allocated for the project. Assistance may be sought from an experienced ISO 17799 consultant at this stage.
  • The scope of the ISMS is determined. This means that the area/s of the organisation to be measured against the standard are selected.
  • This should be a reasonable representation of the organisation’s activities.
  • A review of existing documentation takes place to assess the extent of measures already in place, such as the ISO 9000 quality manual and security policies.
  • A gap analysis is undertaken to identify the gaps between existing and required controls, processes and procedures.
  • An inventory is taken of all relevant information assets.
  • A risk assessment is carried out in order to determine the extent of risk to the ISMS, often comparing impact of risks with the likelihood of these risks actually occurring. A Risk Assessment document is the resulting deliverable.
  • Once risks have been identified and established in the Risk Assessment document, the organisation must decide how such risks are to be managed. From these decisions, responsibilities for managing these risks are determined and documented.
  • Appropriate controls and objectives to be implemented are selected, either from the standard, or not, as the case may be. The standard does not contain an exhaustive list, and additional controls and objectives may be selected. A Statement of Applicability (SoA) is the resulting deliverable following selection of controls.
  • Policies are created based on the SoA.
  • Relevant procedures based on the policy definitions and guidelines are created and documented.
  • A training programme is undertaken to educate all employees to ensure that good practice for Information Security is adopted throughout the business.
  • A programme of compliance monitoring is implemented. This is to ensure that the good work achieved to date is maintained.
  • Once compliance has been achieved, certification may be optionally sought from an accredited body. This requires an audit, which will examine the organisation’s adherence to the standard. A successful audit result will mean that the organisation will gain certification.
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