ISO/IEC 27035
ISO27k-aligned security awareness service

ISO/IEC 27035:2011 Information technology — Security techniques — Information security incident management


Information security controls are imperfect in various ways: controls can fail, work partially, or be completely missing (e.g. not implemented or not operational). Consequently, incidents are bound to happen since preventive controls are not totally reliable and effective.

Managing incidents effectively involves detective and corrective controls designed to minimize adverse impacts, gather forensic evidence (where applicable) and ‘learn the lessons’ in terms of prompting improvements to the ISMS, especially the implementation of more effective preventive controls.

Information security incidents commonly involve the exploitation of previously unrecognised and/or uncontrolled vulnerabilities, hence vulnerability management (e.g. applying relevant security patches to IT systems and addressing control weaknesses in procedures) is part preventive and part corrective action.

Scope and purpose

The standard covers the processes for managing information security events, incidents and vulnerabilities.

The standard expands on the information security incident management section of ISO/IEC 27002. [The updated 2016 version will cross-reference that section and explain its relationship to the ISO27k eForensics standards.]

Structure and content

The standard lays out a process with 5 key stages:

  1. Prepare to deal with incidents e.g. prepare an incident management policy, and establish a competent team to deal with incidents;
  2. Identify and report information security incidents;
  3. Assess incidents and make decisions about how they are to be addressed e.g. patch things up and get back to business quickly, or collect forensic evidence even if it delays resolving the issues;
  4. Respond to incidents i.e. contain them, investigate them and resolve them;
  5. Learn the lessons - more than simply identifying the things that might have been done better, this stage involves actually making changes that improve the processes.

The standard provides template reporting forms for information security events, incidents and vulnerabilities.

Status of the standard

ISO/IEC 27035 upgraded and replaced ISO TR 18044. It was published in 2011.

ISO/IEC 27035:2011 is currently being revised and extended, splitting it into three parts that are expected to be published in 2016.

ISO/IEC 27035-1: principles of incident management (draft)

Scope & purpose: part 1 outlines the concepts and principles underpinning information security incident management and introduces the remaining two parts. It describes an information security incident management process consisting of five phases, and says how to improve incident management.

Content: the incident management process is described in five phases closely corresponding to the five phases in the first edition:

  1. Plan and prepare: establish an information security incident management policy, form an Incident Response Team etc.
  2. Detection and reporting: someone has to spot and report “events” that might be or turn into incidents;
  3. Assessment and decision: someone must assess the situation to determine whether it is in fact an incident;
  4. Responses: contain, eradicate, recover from and forensically analyze the incident, where appropriate;
  5. Lessons learnt: make systematic improvements to the organization’s management of information security risks as a consequence of incidents experienced.

Status: at DIS stage. Some of the definitions in the standard differ from those stated in ISO/IEC 27000.

ISO/IEC 27035-2: guidelines to plan and prepare for incident response (draft)

Scope & purpose: part 2 concerns assurance that the organization is in fact ready to respond appropriately to information security incidents that may yet occur. It addresses the rhetorical question “Are we ready to respond to an incident?” and promotes learning from incidents to improve things for the future. It covers the Plan and Prepare and Lessons Learnt phases of the process laid out in part 1.

Content: after the usual preamble sections come 8 main clauses:

  1. Establishing information security incident management policy
  2. Updating of information security and risk management policies
  3. Creating information security incident management plan
  4. Establishing an Incident Response Team (IRT) [aka CERT or CSIRT]
  5. Defining technical and other support
  6. Creating information security incident awareness and training
  7. Testing the information security incident management plan
  8. Lesson learnt

... plus annexes with incident categorization examples, and notes on “legal and regulatory aspects” (mostly privacy).

Status: at CD stage.

ISO/IEC 27035-3: guidelines for incident response operations (draft)

Scope & purpose: part 3 offers guidance on managing and responding efficiently to information security incidents, using typical incident types to illustrate the approach. It describes the Detection and Reporting, Assessment and Decision, and Response phases of the process laid out in Part 1, plus Post Incident Activity (which isn’t actually identified as a discrete phase!).

Content: there are three main clauses covering IRTs (types, roles, structures, staffing); incident response operations (incident criteria and response processes i.e. monitoring, detecting, assessing, analysing, responding, reporting and learning lessons); and generic examples of incidents (such as denial of service and malware incidents). Annexes offer criteria for categorizing incidents and template forms.

The published version may link-in to the digital forensics standards in ISO27k, since incident response is often the first opportunity to identify that a situation may end up in court, hence the forensic process often starts here.

Status: at CD stage. It has been proposed to publish 27035-3 as a “technical specification” rather than an “international standard” - an obscure change with little real-world impact except that (in theory, at least) it will be possible to update the standard more often, implying that this is a fast moving field of development ...

Personal comments

Notwithstanding the title, the standards actually concern incidents affecting IT systems and networks although the underlying principles apply also to incidents affecting other forms of information such as paperwork, knowledge, intellectual property, trade secrets and personal information. Unfortunately (as far as I’m concerned), the language is almost entirely IT related. That, to me, is yet another opportunity squandered.

I also still don’t understand why the standard was ever split into three: the separate parts are of little value as standalone standards, divorced from the whole. The poor old customers (hey, remember them?) are presumably expected to buy three standards instead of one.

I’m intrigued by the proposed change of part 3 from an IS to a TS. On the one hand, it is just one letter different: I believe the published standard will look basically the same either way. On the other hand, this arcane change will apparently allow the standard to be updated more often ... which seems to me a very odd line of reasoning given that we’ve been operating incident response processes for decades, nay millennia. It’s hardly at the cutting edge of innovation! I smell a rat: perhaps the standard simply needs more work before it is ready to be published (regardless of type), which perhaps hints at problems within the project? Perhaps this is why the standard was split into three?

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