Mathematical models of information system defense against information security threats are proposed based on the classical model of the struggle between two adversaries - the Lanchester model. Using the method of constructing systems of differential equations with a given set of invariants - first integrals, a deterministic model with invariant control and a stochastic model with Viner perturbations and a model with software control with probability 1 have been constructed. The behavior of the systems has been evaluated by means of mathematical modeling in MathCad. Behavior of the constructed models depending on initial conditions is considered. The existence of the stochastic model of information system protection against information security threats protected with probability 1 is established