## 2 Background
### Cloud Computing Deployment Models  
Organisations can deploy cloud computing infrastructure using four different architectures. Deployment depends on the ownership, administration, location, security policies, and nature of the data. The STRIDE analysis of the four cloud computing deployment models is shown in Table 6 and are as follows:  
1. Private cloud: Deployment environment is owned by private sectors solely for the secure storage of company's data [41]. Private clouds are managed mainly by third-party providers but exist on-premise. Access is granted only by company staff to control authorisation management for security purposes. For example, an organisation that wants to make its customer's data available can create a private data centre. Providing more access control over sensitive information and enhanced data security mechanisms to ensure privacy in a private cloud setting. The major drawback of these settings is their purchase cost for equipment and utility bills. 2. Community cloud: A cloud environment collectively owned by a set of organisations with the same motive. The community cloud is similar to a private cloud, but the computational resources and underlying infrastructure are exclusively controlled by two organisations with common privacy and security motives. It is also more expensive than the public cloud, and data access is not regulated correctly due to untrusted parties that might arise. The advantage of the community cloud is the involvement of fair third-party access for security auditing. 3. Public cloud: The public cloud is mainly owned by large organisations offering cloud services, such as Google Apps, Amazon AWS and Microsoft Office 365. Resources in public clouds are primarily provided as a service at a pass-as-you-go fee. The benefits are mainly on-demand purchases: the more the usage, the more the payment. Public cloud users are mostly home users in their houses accessing the providers' network via the internet. The security issues of the public cloud are its lack of data security and privacy as a result of its public nature. There is no control over the transmission of information or the access to sensitive data [41]. Despite its colossal security limitation, small organisations have benefited from its services due to their limited sensitive information with minimal privacy risks. 4. Hybrid cloud: A hybrid cloud service can be offered by a private cloud owner forming a partnership with a public owner, making it more complex because of the involvement of two or more cloud providers. This approach allows the cost-effectiveness and scalability of public cloud environments without exposing data to third-party and mission-critical software applications. The hybrid system offers private cloud features, enabling rapid scalability features of the public cloud. Overall, it provides a drastic improvement to organisational agility and offers greater flexibility to business when compared to other approaches. The security limitations of the hybrid cloud are the limitations of the public cloud, such as public exposure of sensitive information, which poses a significant security risk. An approach to solving this issue is the idea of identity and access management to cloud facilities. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Infrastructure as a Service** & **Platform as a Service** & **Software as a Service** \\ \hline Spoofing & & X & X \\ Tampering & & & X \\ Repudiation & & & X \\ Information Disclosure & & & X \\ Denial of Service & X & X & X \\ Elevation of Privilege & X & X & X \\ \hline \hline \end{tabular} The symbol X denotes the existence of a STRIDE component.  
\end{table} 
Table 5: Cloud service delivery STRIDE analysis. The different deployment models of the cloud provide sharing of user data to more than one operating organisation, sometimes for Personal Identity Information (PII) authorisation. Organisations must maintain information confidentiality and integrity to avoid data tampering by unauthorised users in communicating data across boundaries.