The past five years of research have highlighted many potential benefits of integrating Reconfigurable Intelligent Surfaces (RISs) into wireless communication systems. The capacity and reliability can be significantly improved by controlling these surfaces to enhance the channel conditions. In this webinar, we will instead look at the dark side of the RIS technology: the harm it might cause if not properly controlled. The issues could either be accidental or intentional. One example is that another entity controls the RIS, typically to enhance the communication in an adjacent frequency band. This might inadvertently hurt the performance in your band and cause a new pilot contamination phenomenon. In the worst case, the RIS might be hijacked by someone with malicious intent, who could purposely configure it to reduce your communication performance and create unusual phenomena. How harmful might these issues be in practice?