Information security of the computer systems is focused on securing its characteristics like confidentiality, integrity and accessibility from different by themselves unfavourable effects. A potentially possible unfavourable effect is construed as threat. To prevent or complicate realization of threats and reduce possible damage, they create and maintain in active capacity an actions system of securing information in computer systems. The system includes computer system, physical environment, personnel and information. To secure its characteristics in the computer systems it is very important to consider a non-technical aspect, in particular a personnel aspect (for example, boss, administrator and user). Due to that, social engineering techniques are proposed to assess the information security. Within the techniques, personnel sensitiveness is taken as its weakness, demands, mania (addiction) and interests. Their manipulation allows get unauthorized access to information without destroying and distortion of the main for him system creating features (integrity, development). It results in the new model of personnel behavior, creation of favourable conditions to realize information threat and, consequently, reduction of the information security capability of the system to prevent the effects. It is reflected in the forms of fraud, cheating, deception, intrigue, hoax and provocation. The use of each form is preceded by defining its content via a thorough planning, organization and control. These actions make the basis of the social engineering techniques. On one side, they can be realized via modern telecommunication techniques. On the other side, it involves establishing direct contact with personnel. Thus, it is possible to disclose, neutralize and prevent information vulnerability in computer systems using social engineering techniques. It raises its security in view of a non-technical aspect.