The article deals with the influence of information on the Internet. The growth and importance of resources of a new type – social networks, forums, blogs – as a means to discuss different events, problems, distribution of opinions, influencing actions of network users, have an increasing influence on the existence of modern man. A specific feature of Internet resources is the principle of attracting users to familiarize with the content and its multiple replication. While questions of credibility, reliability, objectivity of information are not taken into account. The use of information flows by hackers suggests the possibility of providing informational-psychological influence on emotional and sensitive, rational-volitional and intellectual spheres of the subconscious and psyche receptors, resulting in the formation of their predictable views, opinions, behaviour that directly or indirectly contribute to the objectives of an attacker. All this testifies to the topicality of the problems of assessing the influence of information on users of Internet resources. The article highlights the main factors complicating the analysis in the field of information effects: the rapid development of information technologies and means of communicating informational messages to the recipients; the inability to predict the patterns of behaviour of subjects of impact; inability to give an accurate estimate of what the message reached the recipient, and to assess the impact of informational influence. The author justifies a probabilistic approach to assessing the impact of Internet resources on users' opinions. The results of mathematical calculations are graphically illustrated and confirmed by the statistical information obtained with the help of modern web analytic systems: GfK Group, Rambler Top 100, Brand Analytics, Yandex Statistics. The results obtained by the author during the survey of the Internet users revealed resources that have a large audience and high frequency of attendance and are more potential threats to information security. Probabilistic assessment allows to identify the main areas where the buildup of forces and means of ensuring protection from the negative effects of information.
