The proliferation of Internet users is increasing rapidly as a result of network growth in technology (wired and wireless) in recent years, cloud computing services has gained attention in the scientific and industrial communities. Cloud computing provides a flexible and cost effective services for consumers and companies through offering services, resources and infrastructure for providers. Cloud computing is a sub-domain of computer network so security issues are a challenge for cloud computing spread, there are many security issues and concerns appear while using cloud services. Protecting data from threats and attacks is the most challenging tasks now-a-days, since people and companies stores confidential data in the cloud.