Nowadays, the systems developed to integrate real physical processes and virtual computational processes -the cyber-physical systems (CPS), are used in multiple areas of industry and critical national infrastructure, such as manufacturing, medicine, traffic management and security, automotive engineering, industrial process control, energy saving, ecological management, industrial robots, technical infrastructure management, distributed robotic systems, protection target systems, nanotechnology and biological systems technology. With wide use, the level of IT and cyberrisks increases drastically and successful attacks against the CPS will lead to unmanageable and unimaginable consequence. Thus, the need in well-designed risk assessment system of CPS is clear and such system can provide an overall view of CPS security status and support efficient allocations of safeguard resources. The nature of CPS differs from IT mainly with the requirement for real-time operations, thus, traditional risk assessment method for IT system can be adopted in CPS. Design of a unified modelling language based domain specific language described in this paper achieves synergy from in IT industry widely used UML modelling technique and the domain specific risk management extensions. As a novelty for UML modelling, especially for simulation purposes, the presented DSL is enriched by a set of stochastic attributes of modelled activities. Such stochastic attributes are usable for further implementation of discrete-event system simulators.