For further clarification of methodological issues of the social network’s information security we stratified the systems that support human relations into three components of different nature: computer, communication and social ones. A security model for a network component is developed using consideration of security for individual nodes. Modeling of attacks on networks in whole is analyzed taking into account specification of network security level. The results for real computer, communication and social entities supported that for a network attacked intentionally it is better off allocating the investment proportionally to degree centralities of the nodes rather than uniformely. The analysis further hints that to make investment justifiable to protect a network, its proprietor should spend lesser than to reach approximately 0.4 of network security level.