The increasing reliance on digital technologies, particularly the Internet of Things (IoT), drives the growth of digital twins (DTs). However, implementing DTs in industrial settings poses challenges, including integration, synchronization, data governance, and security. This paper explores how the STRIDE methodology can be applied to secure DTs, focusing on external and internal communications. The paper aims to bridge the gap in DT security by suggesting focus areas for STRIDE analysis in industrial DT projects. The focus areas provide a way to look at the security of DT in various deployment scenarios: DT development, deployment in replication mode, deployment in simulation mode, and using DT infrastructure for lateral movement. The use of focus areas has been illustrated with a short case study of a DT representing a chemical plant.