Insider threat is a security threat which originates within an organisation. For instance, an existing or a former employee or a business partner possessing confidential data and information may turn out to be a threat to the security of an organisation.
Further, insider threats can be malicious or accidental. In case of malicious threats, a user purposely attempts to obtain some confidential data. On the other hand, accidental threat is an attack where data loss occurs from a known user having no malicious intent.