The textbook examines the actual security issues for open information systems and network technologies. Great attention is paid to organizational, legal, informational and analytical activities in the area of ensuring the security for data, information and knowledge. The textbook is intended for students enrolled for the training field 09.04.03 «Applied Informatics» («Master» qualification), in the discipline «Integrated Information Security». This textbook may be of benefit to students of higher educational institutions enrolled in the specialty «Applied Informatics (by knowledge domains)» and other economic specialties.