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AusCERT 2013: Designing Privacy by Design

I presented my latest privacy engineering tools to the AusCERT 2013 information security conference. Here's the abstract and conference handouts.

Abstract

Privacy by Design is a concept founded by the Ontario Privacy Commissioner Dr. Ann Cavoukian. Dubbed "PbD", it's basically the same good idea as designing in quality, or designing in security. It has caught on nicely as a mantra for privacy advocates worldwide. The trouble is, few designers or security professionals can tell what it means.

Privacy continues to be a bit of a jungle for security practitioners. It's not that they're uninterested in privacy; rather, it's rare for privacy objectives to be expressed in ways they can relate to. Only one of the 10 or 11 or more privacy principles we have in Australia is ever labelled "security" and even then, all it will say is security must be "reasonable" given the sensitivity of the Personal Information concerned. With this legalistic language, privacy is somewhat opaque to the engineering mind; security professionals naturally see it as meaning little more than encryption and maybe some access control.

To elevate privacy practice from the personal plane to the professional, we need to frame privacy objectives in a way that generates achievable design requirements. This presentation will showcase a new methodology to do this, by extending the familiar standardised Threat & Risk Assessment (TRA). A hybrid Privacy & Security TRA adds extra dimensions to the information asset inventory. Classically an information asset inventory accounts for the confidentiality, integrity and availability (C.I.A.) of each asset; the extended methodology goes further, to identify which assets represent Personal Information, and for those assets, lists privacy related attributes like consent status, accessibility and transparency. The methodology also broadens the customary set of threats to include over-collection, unconsented disclosure, incomplete responses to access requests, over-retention and so on.

The extended TRA methodology brings security and privacy practices closer together, giving real meaning to the goal of Privacy by Design. Privacy and security are sometimes thought to be in conflict, and indeed they often are. We should not sugar coat this; after all, systems designers are of course well accustomed to tensions between competing design objectives. To do a better job at privacy, security practitioners need new tools like the Security & Privacy TRA to surface the requirements in an actionable way.

The hybrid Threat & Risk Assessment

TRAs are widely practiced during requirements analysis stages of large information systems projects. There are a number of standards that guide the conduct of TRAs, such as ISO 31000. A TRA first catalogs all information assets controlled by the system, and then systematically explores all foreseeable adverse events that threaten those assets. Relative risk is then gauged, usually as a product of threat likelihood and severity, and the set of threats to be prioritised according to importance. Threat mitigations are then considered and the expected residual risks calculated. An especially good thing about a formal TRA is that it presents management with the risk profile to be expected after the security program is implemented, and fosters consciousness of the reality that finite risks always remain.

The important privacy qualities of Personal Information assets include Accessibility, Permissibility (to disclose), Sensitivity (of e.g. health information), Transparency (of the reasons for collection) and Quality. Typical threats to privacy include over-collection (which can be an adverse consequence of excessive event logging or diagnostics), over-disclosure, incompleteness of records furnished in response to access requests, and over-retention of PI beyond the prima facie business requirement. When it comes to mitigating privacy threats, security practitioners may be pleasantly surprised to find that most of their building blocks are applicable.

The hybrid Security-Privacy Threat & Risk Assessment will help ICT practitioners put Privacy by Design into practice. It helps reduce privacy principles to information systems engineering requirements, and surfaces potential tensions between security practices and privacy. ICT design frequently deals with competing requirements. When engineers have the right tools, they can deal properly with privacy.

AusCERT 2013 Handouts attached below.