The concept of Mobility as a Service (MaaS) was born in Finland and it is rapidly spreading worldwide [1]. Keypoint of a MaaS provider is that it shall offer a unique and seamless interface to its users, aggregating heterogeneous transport options offered by different mobility providers (e.g., different agencies providing transportation by taxi, bus, train, plane, car-sharing, etc.), handling the whole experience of traveling, from providing information, to travel planning, and payments. To effectively support the creation of a market of MaaS providers, we envision the creation of ICT infrastructures based on microservices. This modern and renowned development model [2] fosters the creation of an ecosystem of reusable components. In the context of MaaS, microservices shall efficiently and flexibly combine heterogeneous data sources, such as available transport options, real-time data regarding vehicles and infrastructures, pricing, etc., to provide customized travel planning, information and ticketing to final users, as well as monitoring and strategic planning tools to policy-makers. We are currently developing one of such infrastructures as a marketplace for mobility services, called Smart Mobility for All (SMAll). In our vision, SMAll is the enabling technology to solve the challenges of the MaaS market, from developing user-contributed, crowd-sourced applications, to launching a MaaS operator, to planning effective and sustainable transport policies for smart cities. However, we recognize that such a promising platform as SMAll has a lot of security issues derived from its openness regarding the usage, deployment, and (above all) reliability of its services.