Enterprises are increasingly relying on Cloud services (e.g….
Questions
Enterprises аre increаsingly relying оn Clоud services (e.g., Amаzоn AWS) for a variety of reasons. In this question, we want to explore storage and processing of data in a Cloud environment when there are mandatory access control requirements for the data. Assume authentication and authorization are correctly implemented in a public cloud where resources are shared among multiple applications that belong to different tenants who compete with each other (e.g., two banks). Answer the following questions for this system. A hypervisor allocates resources to various virtual machines (VMs) in the Cloud environment. If the Cloud uses elastic resource allocation, which moves resources across VMs dynamically, covert channels across competing tenants could be a concern. Answer the following questions for this system. If CPUs can be reallocated between different tenants dynamically, can this lead to a covert channel? If your answer is yes, explain how a covert channel can be set up? (2+2 pts.) If a covert channel can be established, would this be a timing or storage covert channel? Explain your answer. (2 pts.) If your answer for question 1.I is yes, would the channel be noisy? Explain your answer. (2 pts.) True or false: Side channels are not a concern in the above Cloud environment. Explain your answer. (2 pts.) Can a storage covert channel be created in this system which allows data to be transferred from tenant T1's process to a process of tenant T2. Explain your answer by showing how a covert channel can be set up or why it is not possible. (1+2 pts.) Assume it has been determined that the Cloud provider must address covert channel concerns of its tenants. We discussed several techniques for mitigation of covert channels. Two examples of such techniques are static resource allocation and the pump. Can timing covert channels be mitigated with static resource allocation? Explain your answer. (1+2 pts.) Could the pump be used for covert channel mitigation in an environment where applications of different tenants do not interact with each other? Explain what types of covert channels can be mitigated using a pump. (2+2 pts.) Could the shared resource matrix (SRM) be used to detect covert channels in such a system when different tenant applications run in separate virtual machines? If yes, explain how or discuss why it is not possible. (2+2 pts.) Assume that when user U's process P makes a request for file F in SELinux, discretionary and type enforcement (TE) permissions are granted. In the multi-level security (MLS) part of the security context of F, the security level is s5. You can assume that both F and U have their compartment set to co..c1023. Answer if the following statements are true or false, and briefly explain your answer. U can never read F when the effective security level in its security context is s4. (2 pts.) U can always read F when the clearance level in its security context is s6. (2 pts.) U may be able to read F when its effective security level is s3 and its clearance level is s6. Explain your answer. (2 pts.)
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