With the adoption of Federal Law No. 187 "On the Security of Critical Information Infrastructure", the implementation of which in practice is not possible without a comprehensive assessment of information security (IS) of subjects of critical information infrastructure (SСII).However, the currently existing regulatory documents of regulators do not consider SСII from the point of view of a systematic approach, the infrastructural component of SСII is not taken into account when building an information protection system. At the same time, the assessment of IS SСII without taking into account the effect on the state and behavior of the system of inter-object and intersubject connections arising in the system leads to an error in the assessment, since the system itself, under certain conditions, can generate infrastructural destructivism. Thus, the error in assessing the ISSII arises due to the failure to take into account the indicator of the SСII's inability to implement its functionality in full under the influence of infrastructure risks, i.e. infrastructural destructivism. From the point of view of the theory of sustainability, this indicator can be correlated with the category of “infrastructure sustainability of SСII”. The proposed by the authors of the study, the model for assessing the infrastructure sustainability (IS) of SСII is presented 1) using the apparatus of cognitive modeling, 2) using the apparatus of the theory of reliability of technical systems. Within the framework of cognitive modeling, the power of concepts is set by experts. In the presented study, for this assessment, it is proposed to use the apparatus of logical-probabilistic modeling, through a clear structuring of the system - SСII. Thus, the assessment of the infrastructure stability of the SCII is characterized by the possibility of assessing the probability of no-failure operation of the facilities of the CII and preventing failures in the functioning of the CII spheres, which guarantees stability and the required level of information security. In this case, the problem of assessing IS in this case acquires a key character in the comprehensive assessment of IS SСII.
