Abstract. In recent years, the threat of cyberattacks has been growing rapidly in numerous industrial sectors that have an impact on our daily life. One of these is the space industry, where the risk of hacking a single satellite can lead to dangerous effects not only for economics but also for Earth critical infrastructure like: transportation systems, water networks, and electric grid. The vulnerability of complex space systems has already been demonstrated in the past. In 1998, for example, hackers took control of the ROSAT X-Ray satellite pointing its solar panels directly to the Sun and causing physical damage. Nowadays, since the attention is moved on small and less sophisticated system, such as CubeSat, the risk of cyber intrusions is even higher as the COTS (Commercial-Off-The-Shelf) technology they use is based on open-source operating systems. In order to counteract this imminent problem, the development of a high-fidelity CubeSat digital model is needed to study and solve related space cybersecurity issues. In fact, thanks to the virtual prototype, what-if simulations can be performed allowing to analyze different cyberattacks scenarios and predict undesirable events on the CubeSat flying on its operative orbit. Moreover, the building of the digital model requires a holistic modeling approach and simulation tools which allows to consider Multiphysics phenomena occurring on the space system itself. Finally, the possibility of connecting the virtual model to a real space system, obtaining the so-called Digital Twin (DT), will help engineers to conduct more accurate actions during the mission.