The RMF Is a Multilevel Loop


The RMF shown in Figure 2-1 has an obvious loop. This loop is meant to graphically represent the idea that risk management is a continuous process. That is, identifying risks only once during a software project is insufficient. The idea of "crossing off a particular stage" once it has been executed and never doing those activities again is incorrect. Though the five stages are shown in a particular serial order in Figure 2-1, they may need to be applied over and over again throughout a project, and their particular ordering may be interleaved in many different ways.

There are two main reasons for this complication. First, risks can crop up at any time during the software lifecycle. One natural way to apply a cycle of the loop is during each particular software lifecycle phase. For example, software risks should be identified, ranked, and mitigated (one loop) during requirements and again during design (another loop). Second, risks can crop up between stages, regardless of where in the process a project finds itself.[4]

[4] Note that the process-agnostic view described in Chapter 1 still holds here. I am not suggesting the utility of any one software process over any other. Just like the touchpoints, the RMF is process agnostic as well.

In addition to the issue of continuous looping is a further complication regarding level of application. Put simply, the RMF is fractal. In other words, the entire process can be applied at several different levels. The primary level is the project level. Each stage of the loop clearly must have some representation during a complete project in order for risk management to be effective. Another level is the software lifecycle phase level. The loop will most likely have a representation at the requirements phase, the design phase, the architecture phase, the test planning phase, and so on. A third level is the artifact level. The loop will have a representation during both requirements analysis and use case analysis, for example. Fortunately, a generic description of the validation loop as a serial looping process is sufficient to capture critical aspects at all of these levels at once.

In order to facilitate the learning process, this chapter presents the RMF as a series of stages, tasks, and methods that can be performed in succession, each stage following a particular process and producing a new set of work products and metrics that enhances and clarifies previously created data sets. In reality I describe how the RMF encompasses a particular cycle of the loop that is repeatedly executed on more than one level. The RMF loop restarts continuously so that newly arising business and technical risks can be identified and the status of existing risks currently undergoing mitigation can be kept up.

Understanding that the risk management process is by nature cumulative, and at times arbitrary and difficult to predict (depending on project circumstances), is an important insight. Given this insight, I acknowledge that the practice of specific RMF stages, tasks, and methods (as described serially here, for pedagogical reasons) may occur independently of one another, in parallel, repeatedly, and unsystematically.

Analysts may "skip through" an analytical process, as information gained from the performance of one activity may require the analyst to perform an activity located earlier, or several steps later, in the process cycle. For instance, after finding a rare technical risk, an analyst may need to conduct additional research prior to reprioritizing the risk tables and updating the risk mitigation strategy. In light of our discussion, users of the RMF should focus more on the basic concepts and activities presented here than on the particular order they are presented in.

In practice, less experienced analysts should rely on following these processes as closely as possible, preserving order, and proceeding in continuous loops. Expert analysts are likely to devise work patterns that use the concepts and processes described here, but in a less ordered way.




Software Security. Building Security In
Software Security: Building Security In
ISBN: 0321356705
EAN: 2147483647
Year: 2004
Pages: 154
Authors: Gary McGraw

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