A security event is a change in the everyday operations of a network or information technology service indicating that a security policy may have been violated or a security safeguard may have failed. In a computing context, events include any identifiable occurrence that has significance for system hardware or software. Security events are those that may have significance to the security of systems or data.
The first indication of an event may come from a software-defined alert or by end users notifying a help desk that, for example, network services have slowed down. As a rule, an event is a relatively minor occurance or situation that can be resolved fairly easily and events that require an IT administrator to take action are classified as incidents. A help desk ticket from a single user reporting that they think they have contracted a virus is a security event, because it could indicate a security issue. If evidence of the virus is found on the user's computer, however, it can be considered a security incident.
According to a report from threat detection vendor Damballa, organizations surveyed had an average of 10,000 security events a day. Security products such as antivirus software can reduce the number of security events and many incidence response processes can be automated to make the workload more manageable. Events that don't require action by an administrator may be handled automatically by security information and event management (SIEM) products.