Managing Information Security Risk: Organization, Mission, and Information System View
CHAPTER TWO > 2.4 TIER TWO—MISSION/BUSINESS PROCESS VIEW > 2.4.2 Enterprise Architecture

2.4.2 Enterprise Architecture

A significant risk-related issue regarding the ability of organizations to successfully carry out
missions and business functions is the complexity of the information technology being used in
information systems. To address this complexity and associated potential risk, organizations need
a disciplined and structured approach for managing information technology assets supporting
34 The identification of organizational mission/business processes includes defining the types of information that the
organization needs to successfully execute those processes, the criticality and/or sensitivity of the information, and the
information flows both internal and external to the organization.
35 Risk response strategies are described in Appendix H.
their mission/business processes. Providing greater clarity and understanding of the information
technology infrastructure of organizations including the design and development of the associated
information systems is a prerequisite for maximizing the resilience and wise use of these systems
in the face of increasingly sophisticated threats. This type of clarity and understanding can be
effectively achieved through the development and implementation of enterprise architecture.
Enterprise architecture is a management practice employed by organizations to maximize the
effectiveness of mission/business processes and information resources in helping to achieve
mission/business success. Enterprise architecture establishes a clear and unambiguous connection
from investments (including information security investments) to measurable performance
improvements whether for an entire organization or portion of an organization. Enterprise
architecture also provides an opportunity to standardize, consolidate, and optimize information
technology assets. These activities ultimately produce information systems that are more
transparent and therefore, easier to understand and protect. In addition to establishing a roadmap
for more efficient and cost-effective usage of information technology throughout organizations,
enterprise architecture provides a common language for discussing risk management issues
related to missions, business processes, and performance goals-enabling better coordination and
integration of efforts and investments across organizational and business activity boundaries. A
well-designed enterprise architecture implemented organization-wide, promotes more efficient,
cost-effective, consistent, and interoperable information security capabilities to help organizations
better protect missions and business functions-and ultimately more effectively manage risk.
The Federal Enterprise Architecture (FEA) defines a collection of interrelated reference models
including Performance, Business, Service Component, Data, and Technical as well as more
detailed segment and solution architectures that are derived from the enterprise architecture.36
Organizational assets (including programs, processes, information, applications, technology,
investments, personnel, and facilities) are mapped to the enterprise-level reference models to
create a segment-oriented view of organizations. Segments are elements of organizations
describing mission areas, common/shared business services, and organization-wide services.
From an investment perspective, segment architecture drives decisions for a business case or
group of business cases supporting specific mission areas or common/shared services. The
primary stakeholders for segment architecture are mission/business owners. Following closely
from segment architecture, solution architecture defines the information technology assets within
organizations used to automate and improve mission/business processes. The scope of solution
architecture is typically used to develop and implement all or parts of information systems or
business solutions, including information security solutions. The primary stakeholders for
solution architectures are information system developers and integrators, information system
owners, information system/security engineers, and end users.
The FEA concepts that define needs‐driven, performance‐based business processes are applied by
organizations, recognizing that effectively managing risk arising from operating in a cyberspace
environment with sophisticated, high‐end threats is a key need and measure of performance.
36 The Federal Enterprise Architecture is described in a series of documents published by the OMB FEA Program
Management Office. Additional information on the FEA reference models and the segment and solution architectures
can be found in the FEA Consolidated Reference Model Document and FEA Practice Guidance, respectively.
Enterprise architecture also promotes the concepts of segmentation, redundancy, and elimination
of single points of failure-all concepts that can help organizations more effectively manage risk.
Segmentation is important because it allows organizations to separate missions/business functions
and operations and the information systems, system components, or subsystems supporting those
missions, functions, and operations from other functions and operations and supporting systems.
Segmentation helps to define more manageable components and to potentially reduce the degree
of harm from a successful threat exploitation of a vulnerability. Segment architecture supports the
concept of segmentation at the highest levels of organizations and the concept is carried forward
through solution architecture (including decomposition of information systems and networks into
subsystems and subnetworks, as appropriate).
The concept of redundancy is also very important in enterprise architecture. With the high
probability of breaches or compromises when threats exploit vulnerabilities in organizational
information systems, the failure or degradation of one or more information system components is
inevitable. To enhance information system resilience as part of risk response, organizational
information systems provide a failover mode that helps to ensure that failed components trigger
appropriate backup components with similar capability. This type of capability is essential to
address the advanced persistent threat in situations where organizations might be required to
operate while under cyber attack in a degraded mode but still providing a sufficient level of
capability to achieve mission/business success. Segment and solution architectures support the
concept of redundancy by establishing a disciplined and structured approach to developing and
implementing key architectural considerations that facilitate replication of critical information
system components, where appropriate.
Finally, the concept of single point of failure and the elimination of such failure points is easily
supported by enterprise architecture. Having the essential visibility and transparency provided in
the architectural design at the organization level exposes potential single points of failure early in
the development process. Thus, single points of failure are effectively addressed by segment and
solution architectures. Failure to address potential single points of failure early in the architectural
design can result in severe or catastrophic effects when those failure points are propagated to
information systems and the actual failure causes a loss of mission/business capability.