The research focuses on topical issue of the Internet security. In particular, the issue of level increase in security of authentication services through additional identification using optimal feature space is being considered. This article is devoted to the practical application of additional identification technologies in authentication services. The paper presents sets of informative features characterizing the access subject. A classification of methods for identifying the user's work environment is proposed. The article presents the experimental results of intercomparison between scientifically-grounded methods and technologies for identifying the user's work environment.