The "No Network is 100% Secure" series
- ISO/IEC 27005:2008 -
A New Standard for Security Risk Management
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ISO/IEC 27005:2008: Organizations of all types are concerned with threats that
could compromise information security. Managing this aspect is usually a primary concern
for information technology (IT) departments. In this context, Information Security Risk
Management should be an integral part of all information security management activities
and should be applied both to the implementation and the ongoing operation of an
Information Security Management System (ISMS). In fact, a systematic approach to
information security risk management is necessary to identify organizational needs
regarding information security requirements and to create an effective ISMS.
The ISO/IEC 27005:2008, a new standard from the International Organization for
Standardization (ISO) and the International Electrotechnical Commission (IEC), describes
the Risk Management Process and its activities for information security and provides
guidelines for Information Security Risk Management and supports the general concepts
specified in ISO/IEC 27001:2005. The ISO information security risk management process
can be applied to the organization as a whole; any discrete part of the organization
(e.g. a department, a physical location, a service); any information system; and any
existing, planned, or particular aspect of control (e.g. business continuity planning).
The information security risk management process consists of:
Context Establishment: intends to define the risk management's boundary.
Risk Analysis (Risk Identification & Estimation phases): intends to evaluate the risk
level.
Risk Assessment (Risk Analysis & Evaluation phases): used to make decisions and take
into account the objectives of the organization.
Risk Treatment (Risk Treatment & Risk Acceptance phases): to reduce, retain, avoid or
transfer the risks.
Risk Communication: to achieve agreement on how to manage risks by exchanging and/or
sharing information about risk between the decision makers and other stakeholders.
Risk Monitoring and Review: to detect any chances in the context of the organization
at an early stage, and to maintain an overview of the complete risk snapshot.
Context Establishment phase: all information about the organization relevant to
the information security risk management context is established. This involves setting
the basic criteria necessary for information security risk management (risk evaluation
criteria, impact criteria, risk acceptance criteria, etc.), defining the scope and
boundaries (all relevant assets, business objectives, business processes, strategies
and policies, legal and regulatory requirements applicable to the organization,
interfaces, etc.) and establishing an appropriate organization operating the information
security risk management (roles and responsibilities).
Risk Identification phase: determines the value of the information assets,
identifies the applicable threats and vulnerabilities that exist (or could exist),
identifies the existing controls and their effect on the risk identified and determines
the potential consequences. In particular, Risk Identification consists of the following
activities:
Assets Identification (within the established scope): performs at a suitable level of
detail that provides sufficient information for the risk assessment. The level of
detail used on the asset identification influence the overall amount of information
collected during the risk assessment. The level can be refined in further iterations
of the risk assessment.
Threats Identification: in this activity threats are identified generically and by
type (e.g. unauthorized actions, physical damage, and technical failures). In this
activity internal experience from incidents and past threat assessments should be i
considered.
Controls Identification: identification of existing controls and check to ensure that
the controls are working correctly. Controls that are to be implemented according to
the risk treatment implementation plans should be considered in the same way as those
that already implemented. For the identification of existing or planned controls, could
be review documents containing information about the controls, check with the people
responsible for information security and the users as to which controls are really
implemented, conduct an on-site review of the physical controls and review results of
internal audits.
Vulnerabilities Identification: that can be exploited by threats to cause harm to assets
or to the organization.
Consequences Identification: identification of damage or consequences to the
organization that could be caused by an incident scenario. An incident scenario is the
description of a threat exploiting a certain vulnerability or set of vulnerabilities in
an information security incident. The impact of the incident scenarios is to be
determined considering impact criteria defined during the context establishment activity.
Risk Estimation: is the phase for assigning values to the probability and
consequences of an identified risk. It consists of the following activities:
Risk Estimation Methodologies: identification of Risk Analysis Methodology. It may be
qualitative or quantitative, or a combination of these, depending on the circumstances.
Qualitative estimation uses a scale of qualifying attributes to describe the magnitude
of potential consequences (e.g. Low, Medium and High) and the likelihood that those
consequences will occur. An advantage of qualitative estimation is its ease of
understanding by all relevant personnel while a disadvantage is the dependence on
subjective choice of the scale. Quantitative estimation uses a scale with numerical
values (rather than the descriptive scales used in qualitative estimation) for
consequences and likelihood, using data from a variety of sources. The quality of the
analysis depends on the accuracy and completeness of the numerical values and the
validity of the models used.
Assessment of Consequence: assess consequences or business impact upon the organization
that might result from possible or actual information security incident (taking into
account the consequences of a breach of information security such as loss of
confidentiality, integrity or availability of the assets). Consequences may be
expressed in terms of monetary, technical or human impact criteria, or other criteria
relevant to the organization. In some cases, more than one numerical value is required
to specify consequences for different times, places, groups or situations The business
impact value can be expressed in qualitative and quantitative forms, but any method of
assigning monetary value may generally provide more information for decision making
and hence facilitate a more efficient decision making process.
Assessment of Incident Likelihood: assess likelihood of each incident scenario and
impact occurring, using qualitative or quantitative estimation techniques. This should
take account of how often the threats occur and how easily the vulnerabilities may be
exploited.
Level of Risk Estimation: assign values (quantitative or qualitative) to the likelihood
and the consequences of a risk. The estimated risk is a combination of the likelihood
of an incident scenario and its consequences.
Risk Evaluation phase: the level of risk is compared against risk evaluation
criteria and risk acceptance criteria (defined during the context establishment phase).
Risk evaluation criteria used to make decisions should be consistent with the defined
external and internal information security risk management context and take into
account the objectives of the organization, the importance of the business process or
activity supported by a particular asset or set of asset and stakeholder views etc.
About the Author
Frank Saxton is a computer network security engineer and Easyrider LAN Pro principle. Home-based in Portland, Oregon, Frank has been designing remote diagnostic and network enterprise monitoring centers since the late 1970s. Prior to becoming a professional systems engineering consultant in 1990, Frank had a 20 year career in computer systems field engineering and field engineering management. Frank has a BSEE from Northeastern University and holds several certifications including Network General's Certified Network Expert (CNX). As a NOC design engineer and architect, Frank works regularly with enterprise-class monitoring tools such as HP Openview Operations, BMC Patrol and others. In his enterprise security audit work, Frank uses sniffers and other professional grade monitoring tools on a daily basis.
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Last modified March 25, 2009
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