Security assessment of virtual machines in open source clouds

A company security perimeter is impaired if virtual machines are migrated from on-premise to the cloud. Although cloud service providers (CSP) offer some security level to migrated virtual machines, mostly from outside the cloud, the cloud customer is challenged with newly raised security challenges due to multi-tenancy, i.e. the threat from other co-tenant virtual machines hosted inside the cloud. CSP also faces threats from all tenants in the cloud. Both CSP and the tenants can be compromised in case of vulnerability. In this paper we analyze virtual machine security threats that might occur by other tenants or outside the cloud. Also, we compare the security level that the most common open source clouds provide for a particular virtual machine. The security assessment is realized for virtual machines with different operating systems.