Cloud Computing provides us a means by which we can access the applications as utilities, over the Internet. It allows us to create, configure, and customize applications online. It offers online data storage, infrastructure and application. The term Cloud refers to a Network or Internet. Applications such as e-mail, web conferencing, customer relationship management (CRM), all run in cloud. Cloud computing is highly promising technology because of its unlimited resource provisioning and data storage services which help us in managing the data as per requirements. But this area is still suffering problem of secure storage and communication of data inside the cloud and in between clouds also. Due to the use of internet and vital remote servers to maintain the data and applications, the cloud computing environment becomes open for the attackers to attack on the user data and communication services. This paper provides review of different security aspects of cloud data storage.