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.