Islamic Azad University
Security concerns have given rise to immerging an active area of research due to the many security threats that many organizations have faced at present. Addressing these issues requires getting confidence from user for cloud applications and services. In this paper, the authors have cast light over the major security threats of cloud computing systems, while introducing the most suitable countermeasures for them. They have also cited the aspect to be focused on when talking about cloud security. They have categorized these threats according to different viewpoints, providing a useful and little-known list of threats. After that some effective countermeasures are listed and explained.