Electromagnetic Security refers to the compliance of electronic devices with Information Security requirements with regards to electromagnetic disturbances, and has important implications where there are Functional Safety or other risks to be managed. In this study, the resilience and the integrity of electronic devices are the topics of interest. Many studies have been devoted to the detection, the analysis and the classification of failures and damage by electromagnetic interference induced on commercial off-the-shelf devices, which mostly require external monitoring and measurement equipment. More recently, an approach based on the exploitation of existing internal resources of the tested devices has been proposed. Monitoring of effects due to exposure to EM fields is important for both EM Security and Functional Safety. This paper shows how this can be done by measuring the existing internal parameters of computers and smartphones during exposure to unintentional or intentional electromagnetic fields.