Apparatus, systems, and methods may operate to receive multiple security event data streams from a plurality of hardware processing nodes, the multiple security event data streams comprising multiple security events. Additional operations may include extracting multiple security events from multiple security event data streams, and classifying the extracted multiple security events to form domain-specific, categorized data streams. A hierarchy of statistical data streams may then be generated from the domain-specific, categorized data streams. Additional apparatus, systems, and methods are disclosed.