Instruments and Systems: Monitoring, Control, and Diagnostics Annotation << Back Approach to Assessing the Security of a Computer Communications Network Based on the Number of Vulnerabilities A.S. BELOV, M.M. DOBRYSHIN, D.E. SHUGUROV, K.M. BOLSHIBRATSKY The purpose of the article is to bring to information security specialists and researchers a new numerical approach to assessing the security of computer communications network, which allows to determine at the stage of commissioning a computer network, the probability that an attacker will be able to detect a vulnerability not protected by means of protection against computer attacks, and at the stage of network operation, the periodicity of updating (updating) of information security system. The maximum duration between updates is determined based on the analysis of time series describing the number of information security events. A distinctive feature of the approach is the integrated accounting of parameters that characterize the security of information, the information technology used and the computer network. The approach makes it possible to increase the reliability of information security level assessment in dynamics, the validity of the periodicity of system modernization. Research methods: logical-hypothetical method, elements of probability theory and mathematical statistics. The main results of the work are analytical expressions of probability of realization and occurrence of vulnerabilities for static and dynamic state of computer communication network, as well as analytical expression allowing to determine the maximum time intervals between security system upgrades. Keywords: information security, computer attacks, information security system, modernization. DOI: 10.25791/pribor.11.2022.1371 Pp. 20-25.