The cloud service provider is responsible for the patching of the hypervisor layer in all three cloud deployment models (IaaS, PaaS, and SaaS). The hypervisor layer is the software that allows the creation and management of virtual machines on a physical server. The hypervisor layer is part of the cloud infrastructure, which is owned and operated by the cloud service provider. The cloud service provider is responsible for ensuring that the hypervisor layer is secure, reliable, and up to date with the latest patches and updates. The cloud service provider should also monitor and report on the status and performance of the hypervisor layer, as well as any issues or incidents that may affect it.
The cloud service customer is not responsible for the patching of the hypervisor layer, as they do not have access or control over the cloud infrastructure. The cloud service customer only has access and control over the cloud resources and services that they consume from the cloud service provider, such as virtual machines, storage, databases, applications, etc. The cloud service customer is responsible for ensuring that their own cloud resources and services are secure, compliant, and updated with the latest patches and updates.
The patching of the hypervisor layer is not a shared responsibility between the cloud service provider and the cloud service customer, as it is solely under the domain of the cloud service provider. The shared responsibility model in cloud computing refers to the division of security and compliance responsibilities between the cloud service provider and the cloud service customer, depending on the type of cloud deployment model. For example, in IaaS, the cloud service provider is responsible for securing the physical infrastructure, network, and hypervisor layer, while the cloud service customer is responsible for securing their own operating systems, applications, data, etc. In PaaS, the cloud service provider is responsible for securing everything up to the platform layer, while the cloud service customer is responsible for securing their own applications and data. In SaaS, the cloud service provider is responsible for securing everything up to the application layer, while the cloud service customer is responsible for securing their own data and user access.
Patching on hypervisor layer is required, as it is essential for maintaining the security, reliability, and performance of the cloud infrastructure. Patching on hypervisor layer can help prevent vulnerabilities, bugs, errors, or exploits that may compromise or affect the functionality of the virtual machines or other cloud resources and services. Patching on hypervisor layer can also help improve or enhance the features or capabilities of the hypervisor software or hardware. Reference := Patching process - AWS Prescriptive Guidance What is a Hypervisor in Cloud Computing and Its Types? - Simplilearn In all three cloud deployment models, (IaaS, PaaS, and ... - Exam4Training Reference Architecture: App Layering | Citrix Tech Zone Hypervisor - GeeksforGeeks

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 primary purpose of the Open Certification Framework (OCF) for the CSA STAR program is to provide global, accredited, and trusted certification of the cloud service provider. According to the CSA website1, the OCF is an industry initiative to allow global, trusted independent evaluation of cloud providers. It 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 OCF aims to address the gaps within the IT ecosystem that are inhibiting market adoption of secure and reliable cloud services. The OCF also integrates with popular third-party assessment and attestation statements developed within the public accounting community to avoid duplication of effort and cost. The OCF manages the foundation that runs and monitors the CSA STAR Certification program, which is an assurance framework that enables cloud service providers to embed cloud-specific security controls. The STAR Certification program has three levels of assurance, each based on a different type of audit or assessment: Level 1: Self-Assessment, Level 2: Third-Party Audit, and Level 3: Continuous Auditing. The OCF also oversees the CSA STAR Registry, which is a publicly accessible repository that documents the security controls provided by various cloud computing offerings2. The OCF helps consumers to evaluate and compare their providers' resilience, data protection, privacy capabilities, and service portability. It also helps providers to demonstrate their compliance with industry standards and best practices.
Reference:
Open Certification Framework Working Group | CSA
STAR | CSA

When applying the Top Threats Analysis methodology following an incident, the scope of the technical impact identification step is to determine the impact on confidentiality, integrity, and availability of the information system. The Top Threats Analysis methodology is a framework developed by the Cloud Security Alliance (CSA) to help organizations identify, analyze, and mitigate the most critical threats to cloud computing. The methodology consists of six steps: threat identification, threat analysis, technical impact identification, business impact analysis, risk assessment, and risk treatment12.
The technical impact identification step is the third step of the methodology, and it aims to assess how the incident affected the security properties of the information system, namely confidentiality, integrity, and availability. Confidentiality refers to the protection of data from unauthorized access or disclosure. Integrity refers to the protection of data from unauthorized modification or deletion. Availability refers to the protection of data and services from disruption or denial. The technical impact identification step can help organizations to understand the severity and extent of the incident and its consequences on the information system12.
The other options are not within the scope of the technical impact identification step. Option A, determine the impact on the controls that were selected by the organization to respond to identified risks, is not within the scope because it is part of the risk treatment step, which is the sixth and final step of the methodology. Option C, determine the impact on the physical and environmental security of the organization, excluding informational assets, is not within the scope because it is not related to the information system or its security properties. Option D, determine the impact on the financial, operational, compliance, and reputation of the organization, is not within the scope because it is part of the business impact analysis step, which is the fourth step of the methodology. Reference := Top Threats Analysis Methodology - CSA1 Top Threats Analysis Methodology - Cloud Security Alliance