1. Any threat of a deliberate unauthorized change to the state of a data processing system. Note: For example, an active threat that would result in modification of messages, insertion of spurious messages, masquerade, or denial of service. 2. The threat of a deliberate unauthorized change to the state of the system. Note: Examples of security-relevant active threats may be: modification of messages, replay of messages, insertion of spurious messages, masquerading as an authorized entity and denial of service.