An external audit is an appropriate tool and technique to support a customer's verification of the cloud service provider's claims regarding its responsibilities according to the shared responsibility model. An external audit is an independent and objective examination of the cloud service provider's policies, procedures, controls, and performance by a qualified third-party auditor. An external audit can provide assurance that the cloud service provider is fulfilling its obligations and meeting the customer's expectations in terms of security, compliance, availability, reliability, and quality. An external audit can also identify any gaps or weaknesses in the cloud service provider's security posture and suggest recommendations for improvement.
An external audit can be based on various standards, frameworks, and regulations that are relevant to the cloud service provider's industry and domain. For example, some common external audits for cloud service providers are:
ISO/IEC 27001: This is an international standard that specifies the requirements for establishing, implementing, maintaining, and continually improving an information security management system (ISMS). An ISMS is a systematic approach to managing sensitive information so that it remains secure. An ISO/IEC 27001 certification demonstrates that the cloud service provider has implemented a comprehensive and effective ISMS that covers all aspects of information security, including risk assessment, policy development, asset management, access control, incident management, business continuity, and compliance.1 SOC 2: This is an attestation report that evaluates the cloud service provider's security controls based on the American Institute of Certified Public Accountants (AICPA) Trust Services Criteria. The Trust Services Criteria are a set of principles and criteria for evaluating the design and operating effectiveness of controls that affect the security, availability, processing integrity, confidentiality, and privacy of a system. A SOC 2 report provides assurance that the cloud service provider has implemented adequate controls to protect the customer's data and systems.2 CSA STAR: This is a program for flexible, incremental, and multi-layered cloud provider certification and/or attestation according to the Cloud Security Alliance's industry leading security guidance and control framework. The CSA STAR program consists of three levels of assurance: Level 1: Self-Assessment, Level 2: Third-Party Audit, and Level 3: Continuous Auditing. The CSA STAR program aims to provide transparency, assurance, and trust in the cloud ecosystem by enabling customers to assess and compare the security and compliance posture of cloud service providers.3 The other options listed are not suitable for supporting a customer's verification of the cloud service provider's claims regarding its responsibilities according to the shared responsibility model. An internal audit is an audit conducted by the cloud service provider itself or by an internal auditor hired by the cloud service provider. An internal audit may not be as independent or objective as an external audit, and it may not provide sufficient evidence or credibility to the customer. A contractual agreement is a legal document that defines the roles, responsibilities, expectations, and obligations of both the cloud service provider and the customer. A contractual agreement may specify the terms and conditions for service delivery, performance, availability, security, compliance, data protection, incident response, dispute resolution, liability, and termination. However, a contractual agreement alone does not verify or validate whether the cloud service provider is actually fulfilling its claims or meeting its contractual obligations. A security assessment is a process of identifying, analyzing, and evaluating the security risks and vulnerabilities of a system or an organization. A security assessment may involve various methods such as vulnerability scanning, penetration testing, threat modeling, or risk analysis. A security assessment may provide useful information about the current state of security of a system or an organization, but it may not cover all aspects of the shared responsibility model or provide assurance that the cloud service provider is complying with its responsibilities on an ongoing basis.

The first step of the Cloud Risk Evaluation Framework is to identify key risk categories. Key risk categories are the broad areas or domains of cloud security and compliance that may affect the cloud service provider and the cloud service customer. Key risk categories may include data security, identity and access management, encryption and key management, incident response, disaster recovery, audit assurance and compliance, etc.
Identifying key risk categories helps to scope and focus the cloud risk assessment process, as well as to prioritize and rank the risks based on their relevance and significance. Identifying key risk categories also helps to align and map the risks with the applicable standards, regulations, or frameworks that govern cloud security and compliance12.
Analyzing potential impact and likelihood (A) is not the first step of the Cloud Risk Evaluation Framework, but rather the third step. Analyzing potential impact and likelihood is the process of estimating the consequences or effects of a risk event on the business objectives, operations, processes, or functions (impact), as well as the probability or frequency of a risk event occurring (likelihood). Analyzing potential impact and likelihood helps to measure and quantify the severity or magnitude of the risk event, as well as to prioritize and rank the risks based on their impact and likelihood12.
Establishing cloud risk profile (B) is not the first step of the Cloud Risk Evaluation Framework, but rather the second step. Establishing cloud risk profile is the process of defining and documenting the expected level of risk that an organization is willing to accept or tolerate in relation to its cloud services (risk appetite), as well as the actual level of risk that an organization faces or encounters in relation to its cloud services (risk exposure). Establishing cloud risk profile helps to determine and communicate the objectives, expectations, and responsibilities of cloud security and compliance, as well as to align and integrate them with the business strategy and goals12.
Evaluating and documenting the risks is not the first step of the Cloud Risk Evaluation Framework, but rather the fourth step. Evaluating and documenting the risks is the process of assessing and reporting on the effectiveness and efficiency of the controls or actions that are implemented or applied to prevent, avoid, transfer, or accept a risk event (risk treatment), as well as identifying and addressing any gaps or issues that may arise (risk monitoring). Evaluating and documenting the risks helps to ensure that the actual level of risk is aligned with the desired level of risk, as well as to update and improve the risk management strategy and plan12. References :=
* Cloud Auditing Knowledge: Preparing for the CCAK Certificate Exam
* Cloud Risk-10 Principles and a Framework for Assessment - ISACA