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H a z a r d A n a l y s i s a n d T h r e a t M o d e l i n g
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Example Quality Assurance Script for Hazard Analysis Reviews
A quality assurance script to ensure compliance with regulatory
requirements might read as follows:
Loop for each requirement in the database
Does the requirement have a hazard associated with it?
If the requirement has a hazard associated with it, is the risk
severe enough to warrant mitigation? If the risk is severe enough
to warrant mitigation, then does the requirement trace to
complementary mitigating requirements? If not, then add the
requirement that appears not to have been mitigated to a
published list of requirements requiring further investigation.
Loop End

resulting in injury, and to prevent that from happening, requirements
are added to the database to ensure that sensors in the door detect
resistance and prevent closure on the passenger. The reflection process
is then completed by creating traces from the hazard requiring
mitigation to the mitigating requirement.

Hazard Analysis and MDRE
Extending a modeling tool to support hazard analysis helps support
performing visual inspections and conducting reviews. Furthermore,
any traces in the model are intrinsic to the relationships. An example
is shown in Figure 11.4 of an X-ray machine use case, along with
potential hazards and mitigating requirements. Note that the symbols
used to indicate hazards can be domain specific, e.g., radiation, toxic
material, biohazard, high voltage, and so on. The use of domain-
specific symbols helps to move the analysis effort from the analyst’s
domain into the subject matter expert’s or customer’s domain,
enabling client and expert reviews (see Chapter 4).

Requirement Hazard Analysis Requires Mitigating Mitigating Is a Mitigating Mitigates
Completed Requirements Requirement Requirement
REQ103.7 REQ101.5
Door closes on Yes Yes REQ103.7.1 No
Engineer signal REQ103.10.3
REQ101.5 Door
Door sensor to Yes No Yes REQ103.7 Close
detect obstruction Hazard
in door Analysis
FIGURE 11.3 Database attributes supporting hazard analysis