The Official (ISC)2 CCSP CBK Reference. Leslie Fife

some challenges for the cybersecurity professional. When resources are pooled, it can lead to multitenancy. A competitor or a rival can be sharing the same physical hardware. If the system, especially the hypervisor, is compromised, sensitive data could be exposed.

      Resource pooling also implies that resources are allocated and deallocated as needed. The inability to ensure data erasure can mean that remnants of sensitive files could exist on storage allocated to another user. This increases the importance of data encryption and key management.

      Measured Service

      Metering service usage allows a CSP to charge for the resources used. In a private cloud, this can allow an organization to charge each department based on their usage of the cloud. For a public cloud, it allows each customer to pay for the resources used or consumed. With a measured service, everyone pays their share of the costs.

      The cloud is especially advantageous for organizations with peaks in their resource needs or cycles of usage. For example, a tax preparer uses more resources in the United States in the beginning of the year, peaking on April 15. Many industries have sales dates: Memorial Day, President's Day, Black Friday, Cyber Monday, Arbor Day, etc. Okay, maybe not Arbor Day. Resource needs peak at these times. A company can pay for the metered service for these peak times rather than maintaining the maximum resource level throughout the year. Maintaining the maximum resources in-house would be expensive and a waste of resources.

      Building Block Technologies

      These technologies are the elements that make cloud computing possible. Without virtualization, there would be no resource pooling. Advances in networking allow for ubiquitous access. Improvements in storage and databases allow remote virtual storage in a shared resource pool. Orchestration puts all the pieces together. The combination of these technologies allows better resource utilization and improves the cost structure of technology. Providing the same resources on-premise can also be accomplished by these technologies, but with lower resource utilization and at a higher cost in many situations. Where costs are not decreased by cloud computing, a case for on-premise resources can be made.

      Virtualization

      Virtualization allows the sharing of servers. Virtualization is not unique to cloud computing and can be used to share corporate resources among multiple process and services. For example, a service can have VMware installed and run a mail server on one virtual machine (VM) and a web server on another VM, both using the same physical hardware. This is resource sharing.

      Cloud computing takes this idea and expands it beyond what most companies are capable of doing. The CSP shares resources among a large number of services and customers (also called tenants). Each tenant has full use of their environment without knowledge of the other tenants. This increases the efficient use of the resources significantly.

In addition, a CSP may have multiple locations. This allows services and data to move seamlessly between locations, improving resource use by the CSP. Services and data can easily be in multiple locations, improving business continuity and fault tolerance. The CSP can use the ease with which virtualization allows the movement of data and services to take advantage of available space and excess capacity, wherever it may be located.

      This can create some security and compliance concerns, when data cannot move freely across borders or jurisdictional issues exist. These issues are best handled during contract negotiation. Another concern is if the hypervisor is compromised, as it controls all VMs on a machine. If the hypervisor is compromised, all data can be compromised. The security of the hypervisor is the responsibility of the CSP.

      Storage

      A variety of storage solutions allow cloud computing to work. Two of these are storage area networks (SANs) and network-attached storage (NAS). These and other advances in storage allow a CSP to offer flexible and scalable storage capabilities.

      A SAN provides secure storage among multiple computers within a specific customer's domain. A SAN appears like a single disk to the customer, while the storage is spread across multiple locations. This is one type of shared storage that works across a network.

      Another type of networked storage is the NAS. This network storage solution uses TCP/IP and allows file-level access. A NAS appears to the customer as a single file system. This is a solution that works well in a cloud computing environment.

      The responsibility for choosing the storage technology lies with the CSP and will change over time as new technologies are introduced. These changes should be transparent to the customer. The CSP is responsible for the security of the shared storage resource.

      Shared storage can create security challenges if file fragments remain on a disk after it has been deallocated from one customer and allocated to another. A customer has no way to securely wipe the drives in use, as the customer does not control the physical hardware. However, the use of crypto-shredding can make these fragments unusable if recovered.

      Networking

      As all resources in a cloud environment are accessed through the network, a robust, available network is an essential element. The Internet is the network used by public and community clouds, as well as many private clouds. This network has proven to be widely available with broad capabilities. The Internet has become ubiquitous in society, allowing for the expansion of cloud-based services.

An IP-based network is only part of what is needed for cloud computing. Low latency, high bandwidth, and relatively error-free transmissions make cloud computing possible. The use of public networks also creates some security concerns. If access to cloud resources is via a public network, like the Internet, the traffic can be intercepted. If transmitted in the clear, the data can be read. The use of encryption and secure transport keeps the data in motion secure and cloud computing safer.

      Databases

      Databases allow for the organization of customer data. By using a database in a cloud environment, the administration of the underlying database becomes the responsibility of the CSP. They become responsible for patching, tuning, and other database administrator services. The exception is IaaS, where the user is responsible for whatever database they install.

      The other advantage of databases offered through a cloud service is the number of different database types and options that can be used together. While traditional relational databases are available, so are other types. By using traditional databases and other data storage tools as well as large amounts of data resources, data warehouses, data lakes, and other data storage strategies can be implemented.

      Orchestration

      Cloud orchestration is the use of technology to manage the cloud infrastructure. In a modern organization, there is a great deal of complexity. This has been called the multicloud. An organization may contract through the VMO with multiple SaaS services. In addition, they may have accounts with multiple CSPs, such as AWS, IBM Cloud Foundry, and Microsoft Azure. In addition, they may be using public, private, and community clouds.

      This complexity could lead to data being out of sync, processes being broken, and the workforce unable to keep track of all the part. Like the conductor of an orchestra, cloud orchestration partners keep all of these pieces working together including data, processes, and application services. Orchestration is the glue that ties all of the pieces together through programming and automation. Orchestration is valuable whether an organization runs a single cloud environment or a multicloud environment.

      This is more than simply automating a task here and a task there. However, automation is used by the cloud orchestration service to create one seemingly seamless organizational cloud environment. In addition to hiding much of the complexity of an organization's cloud environment, cloud orchestration can reduce costs, improve efficiency, and support the overall workforce.