External attestation and certification audit reports are considered the best method to demonstrate

assurance in cloud services to multiple customers because they provide an independent verification

of the cloud service provider’s controls and practices. These reports are conducted by third-party

auditors and offer a level of transparency and trust that cannot be achieved through self-assessments

or internal documents. They help ensure that the cloud provider meets industry standards and

regulatory requirements, which is crucial for customers to assess the risk and compliance posture of

their cloud service providers.

Reference = The importance of external attestation and certification audit reports is supported by the

Cloud Security Alliance (CSA) and ISACA, which state that the CCAK credential prepares IT and

security professionals to ensure that the right controls are in place and to mitigate the risks and costs

of audit management and penalties for non-compliance1.