Security engineering is concerned with building systems that remain secure despite malice or error. It focuses on the tools, processes, and methods needed to design and implement complete systems that proactively and reactively mitigate vulnerabilities. Security engineering is a primary discipline used to achieve system assurance.
Security engineering incorporates a number of cross-disciplinary skills, including cryptography, computer security, tamper-resistant hardware, applied psychology, supply chain management, and law. Security requirements differ greatly from one system to the next. System security often has many layers built on user authentication, transaction accountability, message secrecy, and fault tolerance. The challenges are protecting the right items rather than the wrong items and protecting the right items but not in the wrong way.
Robust Security Design
Robust security design explicitly rather than implicitly defines the protection goals. The Certified Information Systems Security Professional (CISSP) Common Body of Knowledge (CBK) partitions robust security into ten domains (Tipton 2006):
- Information security governance and risk management addresses the framework, principles, policies, and standards that establish the criteria and then assess the effectiveness of information protection. Security risk management contains governance issues, organizational behavior, ethics, and security awareness training.
- Access control is the procedures and mechanisms that enable system administrators to allow or restrict operation and content of a system. Access control policies determine what processes, resources, and operations users can invoke.
- Cryptography can be defined as the principles and methods of disguising information to ensure its integrity, confidentiality, and authenticity during communications and while in storage. Type I devices are certified by NSA for classified information processing. Type 2 devices are certified by NSA for proprietary information processing. Type 3 devices are certified by NSA for general information processing. Type 4 devices are produced by industry or other nations without any formal certification.
- Physical (environmental) security addresses the actual environment configuration, security procedures, countermeasures, and recovery strategies to protect the equipment and its location. These measures include separate processing facilities, restricted access into those facilities, and sweeps to detect eavesdropping devices.
- Security architecture and design contains the concepts, processes, principles, and standards used to define, design, and implement secure applications, operating systems, networks, and equipment. The security architecture must integrate various levels of confidentiality, integrity, and availability to ensure effective operations and adherence to governance.
- Business continuity and disaster recovery planning are the preparations and practices which ensure business survival given events, natural or man-made, which cause a major disruption in normal business operations. Processes and specific action plans must be selected to prudently protect business processes and to ensure timely restoration.
- Telecommunications and network security are the transmission methods and security measures used to provide integrity, availability, and confidentiality of data during transfer over private and public communication networks.
- Application development security involves the controls applied to application software in a centralized or distributed environment. Application software includes tools, operating systems, data warehouses, and knowledge systems.
- Operations security is focused on providing system availability for end users while protecting data processing resources both in centralized data processing centers and in distributed client / server environments.
- Legal, regulations, investigations, and compliance issues include the investigative measures to determine if an incident has occurred and the processes for responding to such incidents.
Given the variety of security needs and various domains that contribute to system security, a commonly applied architecture and design approach is known as “defense in depth.” This approach implements multiple layers of defense and countermeasures, making maximum use of certified equipment in each layer to facilitate system accreditation.
Security engineering is an area of increasing emphasis in the defense domain. Baldwin et al. (2012) provide a survey of the issues and a detailed reference list.
The primary objective of System Security Engineering (SSE) is to minimize or contain defense system vulnerabilities to known or postulated security threats and to ensure that developed systems protect against these threats. Engineering principles and practices are applied during all system development phases to identify and reduce these system vulnerabilities to the identified system threats.
The basic premise of SSE is recognition that an initial investment in “engineering out” security vulnerabilities and “designing-in” countermeasures is a long-term benefit and cost saving measure. Further, SSE provides a means to ensure adequate consideration of security requirements (i.e., physical, personnel, procedural, emission, transmission, cryptographic, communications, operations, and computer security) and, when appropriate, that specific security-related designs are incorporated into the overall system design during the engineering development program. There may be some variation in the SSE process from program to program due mainly to the level of design assurance required of the contractor to ensure that appropriate security controls have been implemented correctly as planned. These specific assurance requirements are elicited early in the program where their specifics can be adequately planned, implemented, and verified in due course of the system development.
The System Security Engineering Management Plan (SSEMP) is a key document to develop for SSE. The SSEMP identifies the planned security tasks for the program and the organizations and individuals responsible for security aspects of the system. The goals of the SSEMP are to ensure that pertinent security issues are raised at the appropriate points in the program, to ensure adequate precautions are taken during design, implementation, test, and fielding, and to ensure that only an acceptable level of risk is incurred when the system is released for fielding. The SSEMP forms the basis for an agreement with SSE representing the developer, the government program office, the certifier, the accreditor, and any additional organizations that have a stake in the security of the system. The SSEMP identifies the major tasks for certification & accreditation (C&A), document preparation, system evaluation, and engineering; identifies the responsible organizations for each task; and presents a schedule for the completion of those tasks.
SSE security planning and risk management planning includes task and event planning associated with establishing statements of work and detailed work plans as well as preparation and negotiation of SSE plans with project stakeholders. For each program, SSE provides the System Security Plan (SSP) or equivalent. An initial system security Concept of Operations (CONOPS) may also be developed. The SSP provides
- the initial planning of the proposed SSE work scope;
- detailed descriptions of SSE activities performed throughout the system development life cycle;
- the operating conditions of the system;
- the security requirements;
- the initial SSE risk assessment (includes risks due to known system vulnerabilities and their potential impacts due to compromise and/or data loss); and
- the expected verification approach and validation results.
These plans are submitted with the proposal and updated as required during engineering development. In the case where a formal C&A is contracted and implemented, these plans comply with the government’s C&A process, certification responsibilities, and other agreement details, as appropriate. The C&A process is the documented agreement between the customer and contractor on the certification boundary. Upon agreement of the stakeholders, these plans guide SSE activities throughout the system development life cycle.
Baldwin, K., J. Miller, P. Popick, and J. Goodnight. 2012. The United States Department of Defense Revitalization of System Security Engineering Through Program Protection. Proceedings of the 2012 IEEE Systems Conference, 19-22 March 2012, Vancouver, BC, Canada. Accessed 28 August 2012 at http://www.acq.osd.mil/se/docs/IEEE-SSE-Paper-02152012-Bkmarks.pdf.
Tipton, H.F. (ed.). 2006. Official (ISC)2 guide to the CISSP CBK, 1st ed. Boston, MA, USA: Auerbach Publications.
Anderson, R.J. 2008. Security Engineering: A Guide to Building Dependable Distributed Systems, 2nd Ed. New York, NY, USA: John Wiley & Sons.
Allen, Julia; Barnum, Sean; Ellison, Robert; McGraw, Gary; and Mead, Nancy. 2008. Software security engineering: a guide for project managers. New York, NY, USA: Addison Wesley Professional.
ISO. 2005. Information technology -- Security techniques -- Code of practice for information security management. ISO/IEC 27002. Geneva, SW: ISO.
ISO. 2007. Information technology -- Security techniques -- Systems Security Engineering -- Capability Maturity Model® (SSE-CMM®) ISO/IEC 21827. Geneva, SW: ISO.
Jurjens, J. 2005. "Sound Methods and effective tools for model-based security engineering with UML." Proceedings of the 2005 International Conference on Software Engineering. Munich, GE: ICSE, 15-21 May.
MITRE. 2012. "Systems Engineering for Mission Assurance." In Systems Engineering Guide. Accessed 19 June 2012 at [http://www.mitre.org/work/systems_engineering/guide/enterprise_engineering/se_for_mission_assurance/].
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