With the importance of information security increasing daily, the importance of physical layer security is increasing along with upper layer security. In recent years, owing to technological advancements such as higher accuracy and lower cost of measuring instruments, higher processing speed of computers, and increasing storage capacity of digital devices, advanced attacks that were previously difficult to implement have been realized. Furthermore, such threats have now extended to general commercial products as well as military applications and diplomatic domains. Hence, in this talk, I would like to introduce the issue of information security degradation through electromagnetic fields, which is a physical security attack that cannot be easily detected. I would also like to introduce the associated mechanism of security degradation by electromagnetic fields, corresponding countermeasures, and standardization trends.