The intensive development of information and telecommunications technology has a very large impact on society. On the one hand, it greatly facilitates many activities in everyday life, such as searching for information, establishing contacts with other people, or controlling household appliances at a distance. On the other hand, it poses serious threats to our personal data, the information we process, or our property. One of the examples of such threats may be radio identification systems, enabling the registration of working time, entry into restricted zones in workplaces and offices, or warehouse data. Copying data from an identification card may allow unauthorized persons access to premises and data that they should not have. The article presents the principles of operation, the results of the conducted research, and their analysis in the aspect of security of the short-range radio frequency identification systems used in relation to the RFID 125 kHz system, broadly used in access control systems or time and attendance systems. Particular attention has been paid to the possibility of unauthorized acquisition of information contained in the identification card in order to, for example, copy it and gain access to specific protected zones. An analysis of the security of such systems was carried out not only in relation to the data carriers themselves but also to complete access control systems installed in buildings. The research focused especially on the ability to determine the range of information penetration, i.e., the distance of remote information acquisition using electromagnetic radiated emissions.