Ready or not, the digitalization of information has come, and privacy is standing out there, possibly at stake. Although digital privacy is an identified priority in our society, few systematic, effective methodologies exist that deal with privacy threats thoroughly. This paper presents a comprehensive framework to model privacy threats in software-based systems. First, this work provides a systematic methodology to model privacy-specific threats. Analogous to STRIDE, an information flow-oriented model of the system is leveraged to guide the analysis and to provide broad coverage. The methodology instructs the analyst on what issues should be investigated, and where in the model those issues could emerge. This is achieved by (i) defining a list of privacy threat types and (ii) providing the mappings between threat types and the elements in the system model. Second, this work provides an extensive catalog of privacy-specific threat tree patterns that can be used to detail the threat analysis outlined above. Finally, this work provides the means to map the existing privacy-enhancing technologies (PETs) to the identified privacy threats. Therefore, the selection of sound privacy countermeasures is simplified.
