Biblio

Security and privacy threat modeling is commonly applied to systematically identify and address design-level security and privacy concerns in the early stages of architecture and design. Identifying and resolving these threats should remain a continuous concern during the development lifecycle. Especially with contemporary agile development practices, a single-shot upfront analysis becomes quickly outdated. Despite it being explicitly recommended by experts, existing threat modeling approaches focus largely on early development phases and provide limited support during later implementation phases.In this paper, we present an integrated threat analysis toolchain to support automated, continuous threat elicitation, assessment, and mitigation as part of a continuous integration pipeline in the GitLab DevOps platform. This type of automation allows for continuous attention to security and privacy threats during development at the level of individual commits, supports monitoring and managing the progress in addressing security and privacy threats over time, and enables more advanced and fine-grained analyses such as assessing the impact of proposed changes in different code branches or merge/pull requests by analyzing the changes to the threat model.

Creating secure and privacy-protecting systems entails the simultaneous coordination of development activities along three different yet mutually influencing dimensions: translating (security and privacy) goals to design choices, analyzing the design for threats, and performing a risk analysis of these threats in light of the goals. These activities are often executed in isolation, and such a disconnect impedes the prioritization of elicited threats, assessment which threats are sufficiently mitigated, and decision-making in terms of which risks can be accepted. In the proposed TMaRA approach, we facilitate the simultaneous consideration of these dimensions by integrating support for threat modeling, risk analysis, and design decisions. Key risk assessment inputs are systematically modeled and threat modeling efforts are fed back into the risk management process. This enables prioritizing threats based on their estimated risk, thereby providing decision support in the mitigation, acceptance, or transferral of risk for the system under design.

Implementing security by design in practice often involves the application of threat modeling to elicit security threats and to aid designers in focusing efforts on the most stringent problems first. Existing threat modeling methodologies are capable of generating lots of threats, yet they lack even basic support to triage these threats, except for relying on the expertise and manual assessment by the threat modeler. Since the essence of creating a secure design is to minimize associated risk (and countermeasure costs), risk analysis approaches offer a very compelling solution to this problem. By combining risk analysis and threat modeling, elicited threats in a design can be enriched with risk analysis information in order to provide support in triaging and prioritizing threats and focusing security efforts on the high-risk threats. It requires the following inputs: the asset values, the strengths of countermeasures, and an attacker model. In his paper, we provide an integrated threat elicitation and risk analysis approach, implemented in a threat modeling tool prototype, and evaluate it using a real-world application, namely the SecureDrop whistleblower submission system. We show that the security measures implemented in SecureDrop indeed correspond to the high-risk threats identified by our approach. Therefore, the risk-based security analysis provides useful guidance on focusing security efforts on the most important problems first.

With the increasingly pervasive role of software in society, security is becoming an important quality concern, emphasizing security by design, but it requires intensive specialization. Security in families of systems is even harder, as diverse variants of security solutions must be considered, with even different security goals per product. Furthermore, security is not a static object but a moving target, adding variability. For this, an approach to systematically address security concerns in software product lines is needed. It should consider security separate from other variability dimensions. The main challenges to realize this are: (i) expressing security and its variability, (ii) selecting the right solution, (iii) properly instantiating a solution, and (iv) verifying and validating it. In this paper, we present our research agenda towards addressing the aforementioned challenges.