The emerging growth and evolution of web based systems and services make the job of audit professionals a complicated and time-consuming one for many enterprises. In this context, continuous process auditing (CPA) systems in the form of audit-as-a-service (AaaS) emerges as an inexpensive and effective approach. A CPA system helps to satisfy process auditing needs and recommendations in the context of distributed enterprise systems while requiring fewer resources and enabling processes to be audited continuously in real-time. We present a conceptual system architecture for Continuous Process Auditing (CPA) based on domain ontologies, audit rules, knowledge learning techniques and audit report recommendation procedures. This approach provides a representation of a CPA system for a process based e-commerce platform, offering customizable audit rule based solutions for audit professionals, system administrators and senior decision makers.