This document surveys aspects of the audit of cloud services including: 1) role and responsibilities of parties conducting audit and description of the interactions between the CSC, CSP, and CSN; 2) approaches for conducting audits of cloud services to facilitate confidence in delivering and using cloud services; 3) examples of available frameworks and standards which can be used for audit schemes, for certification, and for authorization. This document builds upon the cloud auditor role as defined in ISO/IEC 17789 and ISO/IEC 22123. This document is applicable to all types and sizes of organizations that need to plan and conduct internal or external audits, and that use, provide and support cloud services. This document is not intended to describe certification or to identify controls that are published elsewhere.