Cloud Computing (CC) is a internet based computing technology having shared scalable infrastructure that can be used as service by users. Simply CC can be referred as hardware & software deliverable using internet that is also as a service. An outstanding innovation & technology getting popular due to lower-cost, flexibility and scalability as per user's requirement. Regardless of its popularity large organizations, enterprises are reluctant to move on cloud computing due to its security issues, especially user's data security. Organizations have expressed concern over data security as their confidential and sensitive data needs to be stored by service provider at any location globally, that's why security can't be compromised at all. CC has different security issues at different levels like software security, platform security, infrastructure security etc. This research shall take a review and to focus on user's data security i.e. data storage security issues and how to minimize unauthorized access to data, then available solutions will be presented and an access control model will be suggested. It'll help the reluctant users to easily decide to shift on cloud while understanding the risks associated with CC.