Threat Modeling: Designing for Security

Chapter 15Human Factors and Usability

Usable security matters because people are an important element in the security of any system. If you don't consider how people will use your system, the odds are against them using it well. The security usability community is learning to model people, the sorts of decisions you need them to make, and the sorts of scenarios in which they act. The toolbox for addressing these issues is small but growing, and the tools are not yet as prescriptive as you might like. As such, this chapter gives you (in particular the security expert) deeper background than some other chapters, and the best advice available.

Because humans are different from other elements of security, and because the models, threats, and means of addressing them are different, this chapter covers challenges of modeling human factors in terms of security, and the techniques available to address them.

The chapter starts with models of people, as they motivate everything in this chapter. It continues with models of software which are useful for human factors work. These two models interact with threat elicitation techniques which are covered next, and are similar to those you learned about in Part II of this book. Threats in this chapter include those in which an attacker tries to convince a person to take action, and threats in which the computer needs to defer to a person for a decision. After threat elicitation, you'll learn tools and techniques for addressing human factors ...