Information security management system
The governing principle behind an ISMS is that an organization should design, implement and maintain a coherent set of policies, processes and systems to manage risks to its information assets, thus ensuring acceptable levels of information security risk.
ISMS description 
As with all management processes, an ISMS must remain effective and efficient in the long term, adapting to changes in the internal organization and external environment. ISO/IEC 27001 therefore incorporates the typical "Plan-Do-Check-Act" (PDCA), or Deming cycle, approach:
- The Plan phase is about designing the ISMS, assessing information security risks and selecting appropriate controls.
- The Do phase involves implementing and operating the controls.
- The Check phase objective is to review and evaluate the performance (efficiency and effectiveness) of the ISMS.
- In the Act phase, changes are made where necessary to bring the ISMS back to peak performance.
Other frameworks such as COBIT and ITIL touch on security issues, but are mainly geared toward creating a governance framework for information and IT more generally. COBIT has a companion framework Risk IT dedicated to Information security.
There are a number of initiatives focused to the governance and organizational issues of securing information systems having in mind that it is business and organizational problem, not only a technical problem:
- Federal Information Security Management Act of 2002 is a United States federal law enacted in 2002 that recognized the importance of information security to the economic and national security interests of the United States. The act requires each federal agency to develop, document, and implement an agency-wide program to provide information security for the information and information systems that support the operations and assets of the agency, including those provided or managed by another agency, contractor, or other source.
- Governing for Enterprise Security Implementation Guide  of the Carnegie Mellon University Software Engineering Institute CERT is designed to help business leaders implement an effective program to govern information technology (IT) and information security.
- A Capability Maturity Model (CMM) for system security engineering was standardized in ISO/IEC 21827.
- Information Security Management Maturity Model (known as ISM-cubed or ISM3) is another form of ISMS. ISM3 builds on standards such as ISO 20000, ISO 9001, CMM, ISO/IEC 27001, and general information governance and security concepts. ISM3 can be used as a template for an ISO 9001-compliant ISMS. While ISO/IEC 27001 is controls based, ISM3 is process based and includes process metrics. ISM3 is a standard for security management (how to achieve the organizations mission despite of errors, attacks and accidents with a given budget). The difference between ISM3 and ISO/IEC 21827 is that ISM3 is focused on management, ISO 21287 on Engineering.
Need for a ISMS 
Security experts say and statistics confirm that:
- information technology security administrators should expect to devote approximately one-third of their time addressing technical aspects. The remaining two-thirds should be spent developing policies and procedures, performing security reviews and analyzing risk, addressing contingency planning and promoting security awareness;
- security depends on people more than on technology;
- employees are a far greater threat to information security than outsiders;
- security is like a chain. It is as strong as its weakest link;
- the degree of security depends on three factors: the risk you are willing to take, the functionality of the system and the costs you are prepared to pay;
- security is not a status or a snapshot, but a running process.
These facts inevitably lead to the conclusion that security administration is a management issue, and not a purely technical issue.
The establishment, maintenance and continuous update of an ISMS provide a strong indication that a company is using a systematic approach for the identification, assessment and management of information security risks. Critical factors of ISMS:
- Confidentiality: Protecting information from unauthorized parties.
- Integrity: Protecting information from modifying from unauthorized users.
- Availability: Making the information available to authorized users.
A company will be capable of successfully addressing information confidentiality, integrity and availability requirements which in turn have implications:
- business continuity;
- minimization of damages and losses;
- competitive edge;
- profitability and cash-flow;
- respected organization image;
- legal compliance
The chief objective of information security management is to implement the appropriate measurements in order to eliminate or minimize the impact that various security related threats and vulnerabilities might have on an organization. In doing so, information security management will enable implementing the desirable qualitative characteristics of the services offered by the organization (i.e. availability of services, preservation of data confidentiality and integrity etc.).
Large organizations or organizations such as banks and financial institutes, telecommunication operators, hospital and health institutes and public or governmental bodies have many reasons for addressing information security very seriously. Legal and regulatory requirements which aim at protecting sensitive or personal data as well as general public security requirements impel them to devote the utmost attention and priority to information security risks.
Under these circumstances the development and implementation of a separate and independent management process namely an Information Security Management System is the one and only alternative.
The development of an ISMS framework entails the following six steps:
- Definition of security policy,
- Definition of ISMS scope,
- Risk assessment (as part of risk management),
- Risk management,
- Selection of appropriate controls and
- Statement of applicability
Critical success factors for ISMS 
To be effective, the ISMS must:
- have the continuous, unshakeable and visible support and commitment of the organization’s top management;
- be managed centrally, based on a common strategy and policy across the entire organization;
- be an integral part of the overall management of the organization related to and reflecting the organization’s approach to risk management, the control objectives and controls and the degree of assurance required;
- have security objectives and activities be based on business objectives and requirements and led by business management;
- undertake only necessary tasks and avoiding over-control and waste of valuable resources;
- fully comply with the organization philosophy and mindset by providing a system that instead of preventing people from doing what they are employed to do, it will enable them to do it in control and demonstrate their fulfilled accountabilities;
- be based on continuous training and awareness of staff and avoid the use of disciplinary measures and “police” or “military” practices;
- be a never ending process;
See also 
- Asset (computing)
- Attack (computing)
- Enterprise architecture
- Information security management
- IT governance
- IT risk
- ISO 9001
- ISO/IEC 27001
- ISO/IEC 27002
- ISO/IEC 27004
- ISO/IEC 27005
- Security control
- Security information and event management
- Threat (computer)
- Vulnerability (computing)
- WARP (information security)
- TRAC (ISMS)
Notes and references 
- NIST: FISMA Overview
- Caballero, Albert. (2009). "14". Computer and Information Security Handbook. Morgan Kaufmann Publications. Elsevier Inc. p. 232. ISBN 978-0-12-374354-1 Unknown parameter
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- CERT Governing for Enterprise Security Implementation Guide
- Enisa Risk management, Risk assessment inventory, page 8