The aim of this Book is to critically investigate the security management policy in the Cloud computing, and also review on those emerging threats which affect the Confidentiality, Integrity and Availability of Cloud computing services. The study is done using an extensive literature review, and analysis implementation of Cloud threat models. Investigation was put on, on the proposed threat model, using a functional model framework design, and the threat model was used to evaluate the vulnerability of Cloud computing services based on threat model for the Cloud, and threat model for service users. A scenario on the overview of how the attacks take place was also presented. The findings provide us with the fact that Cloud remote services are vulnerable to attacks. In most case the C.I.A of Cloud services were compromised with the assistance of an Insider, and also external threats only succeeds when the Cloud virtual system design is weak. Thus vulnerable virtual system design can easily be penetrated using Man-in-the Middle attack and Distributed Denial of Service attacks (DDOS). All these attacks are characterized by gathering user confidential informations.