Page 1400 - (ISC)² CISSP Certified Information Systems Security Professional Official Study Guide

Control Specifications Development

Security-conscious organizations also ensure that adequate security
controls are designed into every system from the earliest stages of

development. It’s often useful to have a control specifications
development phase in your lifecycle model. This phase takes place
soon after the development of functional requirements and often
continues as the design and design review phases progress.

During the development of control specifications, it’s important to
analyze the system from a number of security perspectives. First,
adequate access controls must be designed into every system to ensure

that only authorized users are allowed to access the system and that
they are not permitted to exceed their level of authorization. Second,
the system must maintain the confidentiality of vital data through the
use of appropriate encryption and data protection technologies. Next,
the system should provide both an audit trail to enforce individual

accountability and a detective mechanism for illegitimate activity.
Finally, depending on the criticality of the system, availability and
fault-tolerance issues should be addressed as corrective actions.

Keep in mind that designing security into a system is not a onetime
process and it must be done proactively. All too often, systems are
designed without security planning, and then developers attempt to
retrofit the system with appropriate security mechanisms.

Unfortunately, these mechanisms are an afterthought and do not fully
integrate with the system’s design, which leaves gaping security
vulnerabilities. Also, the security requirements should be revisited
each time a significant change is made to the design specifications. If a
major component of the system changes, it’s likely that the security
requirements will change as well.

Design Review

Once the functional and control specifications are complete, let the

system designers do their thing! In this often-lengthy process, the
designers determine exactly how the various parts of the system will
interoperate and how the modular system structure will be laid out.
Also, during this phase the design management team commonly sets