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ISO/IEC 27005
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ISO/IEC 27005:2011 Information technology — Security techniques — Information security risk management (second edition)

Note

Although the 2011 version of ISO/IEC 27005 is the latest (current) official release, it still does not reflect the 2013 updates to both 27001 and 27002. The project to update the standard failed and has been restarted. Meanwhile a correction to the 2011 version is in the works as a temporary and partial fix.  Read on for more info.

Introduction

The ISO27k standards are deliberately risk-aligned, meaning that organizations are encouraged to assess the security risks to their information (called “information security risks” in the standards, but in reality they are simply information risks) as a prelude to treating them in various ways. Dealing with the highest risks first makes sense from the practical implementation and management perspectives.

Scope of the standard

The standard ‘provides guidelines for information security risk management’ and ‘supports the general concepts specified in ISO/IEC 27001 and is designed to assist the satisfactory implementation of information security based on a risk management approach.’

It cites ISO/IEC 27000 and the 2005 version of ISO/IEC 27001 as normative (essential) standards, and also mentions ISO/IEC 27002 in the scope section.

Content of the standard

At around 70 pages, ISO/IEC 27005 is a heavyweight standard although the main part is just 26 pages, the rest being mostly annexes with examples and further information for users.

The standard doesn't specify, recommend or even name any specific risk management method. It does however imply a continual process consisting of a structured sequence of activities, some of which are iterative:

  • Establish the risk management context (e.g. the scope, compliance obligations, approaches/methods to be used and relevant policies and criteria such as the organization’s risk tolerance or appetite);
  • Quantitatively or qualitatively assess (i.e. identify, analyze and evaluate) relevant information risks, taking into account the information assets, threats, existing controls and vulnerabilities to determine the likelihood of incidents or incident scenarios, and the predicted business consequences if they were to occur, to determine a ‘level of risk’;
  • Treat (i.e. modify [use information security controls], retain [accept], avoid and/or share [with third parties]) the risks appropriately, using those ‘levels of risk’ to prioritize them;
  • Keep stakeholders informed throughout the process; and
  • Monitor and review risks, risk treatments, obligations and criteria on an ongoing basis, identifying and responding appropriately to significant changes.

Extensive appendices provide additional information, primarily examples to demonstrate the recommended approach.

Status of the standard

The second edition of ISO/IEC 27005 was published in 2011. It reflects the general corporate or enterprise-wide risk management standard ISO 31000:2009 “Risk management - Principles and guidelines” in the specific context of risks to or involving information.

A project to revise the standard in line with the 2013 versions of ISO/IEC 27001 and 27002 made insufficient progress and was cancelled and re-started.  The project may develop a new standard “Guidance on managing  information security risks and opportunities” - a title referring to section 6.1 of ISO/IEC 27001:2013.  The project proposal is ambiguous re its relationship to ISO 31000 though.

April and June updates An extensive (~5 page) technical corrigendum to the 2011 standard was discussed at the SC 27 meeting in April 2017.  The correction severs the normative link to ISO/IEC 27001:2005 and makes some other changes (e.g. removing PDCA) but does not fully reflect ISO/IEC 27001:2013.

The re-started project to revise 27005 is under way, and has (surprise surprise) almost immediately stumbled into the issue of its ambiguous relationship with ISO 31000, and with the ‘risks and opportunities’ section of ISO/IEC 27001:2013 (see comments below).

Further reading

Read more about selecting suitable information risk analysis methods and management tools in the ISO27k FAQ.

Personal comments

The derailment and cancellation of the first 2011 standard update project created a problem for ISO27k in that it is a suite of risk-aligned standards without an adequate explanation of how to handle information risks. The edifice lacks foundations, quite a predicament. However all is not lost because risk management is broadly-applicable and well covered by many other standards, guidelines and approaches, including several in the domain of information risk management, specifically.

A root cause of the predicament concerns how SC 27 [mis]interpreted and adapted the boilerplate wording imposed by JTC1 on ISO/IEC 27001 section 6.1 “Actions to address risks and opportunities”. I believe that section should have addressed risks to and opportunities for the management system, not for information.

That said, there is now a short window of opportunity to revise 27005 to cover information risk management specifically, regardless of the flaws in 27001 section 6.1 that can be addressed separately (by a corrigendum or at the next planned revision of 27001).  However, the committee looks set to perpetuate and compound the original misinterpretation by attempting to cover both aspects, again.

Another issue concerns the curious term “information security risk”. What is that, exactly? It is not explicitly defined as a term. A note to the definition of risk in ISO/IEC 27000 refers to it as the “effect of uncertainty on information security objectives”. A note to the definition of objective says, rather enigmatically, “information security objectives are set by the organization, consistent with the information security policy, to achieve specific results.” So, putting those together, information security risk is defined as “the effect of uncertainty on information security objectives set by the organization, consistent with the information security policy, to achieve specific results”. Frankly I’m none the wiser, if anything more confused by the tortuous explanation.

I hope to persuade SC 27 to change to “information risk”, defined simply as “risk pertaining to information”, where risk remains as currently defined and widely understood.