At present, society is increasingly dependent on certain technologies, services, systems. The failure of such elements would have an impact on the functioning of the state and the very lives of the population. Such elements may be marked as critical if they meet the criteria set. The elements are assessed based on the sectoral and cross-cutting criteria of the country. The current threat is terrorism, which may jeopardize the functioning of critical infrastructure elements. It is, therefore, necessary to pay attention to their security. Security is closely related to concepts such as resilience and vulnerability. In some studies, these two terms are considered identical. The authors of this article consider these two terms as related. The article aims to analyze the approaches to these two concepts and to conclude what the two concepts are related to each other.