Threats can be divided into: - source of origin - internal - accidental, unintentional - external - random - former employee's revenge - fraud - terrorist attack - espionage - for fun - nature of threat - technical - non-technical ## Mechanism of threat formation - refusal to provide a service due to external influence - misleading authorized users - gaining unauthorized access to resources - installation of malware or hidden functionalities ## Malware - ransomware - bot - trojan - rootkit - worm - spyware - virus - keylogger