These questions are from the discretionary and mandatory acc…
These questions are from the discretionary and mandatory access control modules. All students in a class belong to a group G and are able to access class resources because G is granted the necessary permissions. Assume Alice has tested out of a topic and does not need to take the quiz on this topic. The professor does not want Alice to have access to this quiz but wants Alice to remain in group G so she can access other resources. Also, the professor wants to grant access to the quiz to all other students by granting the desired access to G. The mechanisms provided by various operating systems can be used to meet this access control requirement. Explain how this can be achieved most efficiently and correctly in Linux with extended access control lists (EACLs) and in Windows. First, provide the access control entries (ACEs) with their types and permissions for the quiz in each system. After this, discuss which of these ACEs will be checked when Alice tries to access the quiz. (2+2+2+2 pts.) The Bell and La Padula (BLP) and Biba models address confidentiality and integrity of data in a system that supports mandatory access control.. A system follows the read-down rule of BLP, but writes by a user are only allowed at the user’s level (no writes to higher levels are allowed). Does this system satisfy the requirements of the BLP and Biba models? First, describe the BLP and Biba requirements and then explain if the requirements of each model are satisfied. (2+2+2+2 pts.) If both models are used simultaneously by a system and object O has the highest sensitivity level (e.g., top secret), what level of integrity should be assigned to O based on Biba? Is there a drawback to using both of these models at the same time? Provide a brief explanation. (1+2 pts.) A certain company has many customers and some of them have conflict-of-interest (CoI) relationships. Also, employees can only access company data by executing applications approved by the company based on their roles or functions in the company. The people responsible for access provisioning in this company came up with the following scheme. All files of a given customer must be stored in a single directory. Initially, users are allowed to execute applications based on their needs and each application can access files needed by it. Access could be removed when applications execute. In particular, when user U executes application A which accesses files from customer C’s directory, access to all files in directories of customers who have a CoI relationship with C is turned off for application A when it is executed by U. Give two examples of policies discussed in the mandatory access control module of the course that could be used to control access to documents by this company. Explain your answer by discussing the specific access requirements identified by the company that are satisfied by each policy. (4+4 pts.) Does the suggested implementation correctly implement each policy that you recommend for the company? Provide a brief justification for your answer. (2+2 pts.)
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