The increasing networking and decentralization of cyber-physical systems in industry offers high potential; for instance, through a more efficient use of resources and equipment maintenance. On the other hand, this increases the complexity of these Industry 4.0 systems, which are characterized by distributed functional scopes and global information exchange. The high degree of interconnectivity and growing complexity blur the system boundaries making them more susceptible to attacks. Security is therefore a key issue in the operation and acceptance of Industry 4.0 systems. In order to adequately account for security in Industry 4.0 systems, security should be taken into consideration since the early stages of system design (Security-by-design). This should prevent the use of costly and laborious measures in the future. Model-based tools, through which systems and their security aspects can be modelled and analyzed, provide an appropriate approach for this matter. This contribution presents a concept for a model-based design tool which supports security-by-design facilities for Industry 4.0. The objective of this design tool is the development of current and future secure Industry 4.0 systems.