Abstract: In this paper, we propose a model for predicting the dynamics of a generalized efficiency index for corporate computer networks operating under conditions of malicious cyber activity. The model represents the dynamics of the index as a function of the operational efficiency of a corporate network at each instant on a certain time interval. In this case, the level of operational efficiency of the network depends on the operational efficiency of its components and is described by a system of differential equations that take into account both malicious activity and the process of eliminating its effects. Under some simplifying conditions, we find analytical solutions of these equations, which significantly facilitates the prediction of the dynamics of the generalized efficiency index. © 2021, Allerton Press, Inc.