Access Control Flashcards

Question

What is an access control system?

Answer 1

Answer: An access control system consists of a protection state (defines permissions) and an enforcement mechanism (enforces the protection state).

Answer 2

Answer: An access matrix is a technique to represent the protection state, showing what operations subjects can perform on objects.

Answer 3

Answer: A reference monitor is an enforcement mechanism that checks if a request is authorized by the access control policy.

Answer 4

Answer: 1.Complete mediation 2.Tamperproof 3.Verifiable

Answer 5

Answer: Discretionary Access Control (DAC) Mandatory Access Control (MAC) Role-Based Access Control (RBAC) Rule-Based Access Control (RuBAC)

Answer 6

Answer: DAC is an access control method where the owner of a resource sets the policies for who is allowed to access.

Answer 7

Answer: MAC is an access control method where the operating system enforces access permissions and restrictions based on security levels.

Answer 8

Answer: RBAC is an access control method that uses roles and user groups to determine access privileges.

Answer 9

Answer: RuBAC is an access control method that uses rule lists to define access parameters.

Answer 10

Answer: ABAC is an access control method that uses attributes to form policy rules, providing more flexibility than RBAC.

Answer 11

Answer: Auditing is used to enforce the principle of least privilege and minimize risks associated with users retaining unnecessary access rights.

Answer 12

Answer: A secure protection state is one that meets secrecy, integrity, and availability goals.

Answer 13

Answer: A Trojan horse is a program that masquerades as a benign application but contains a malicious function, posing a security risk by potentially leaking sensitive information.

Answer 14

Answer: The Simple-Security Property states that subjects cannot read data that is more secret than their subject is allowed.

Answer 15

Answer: The Security Property states that subjects cannot write data to files that are less secret than they are.

Answer 16

Answer: The authorization module takes the interface’s inputs and converts them into a query for the reference monitor’s policy store.

Answer 17

Answer: The components of access control are: Authentication (verifying user identity), Authorization (specifying access rights), Access (allowing access to resources), Manage (adding/removing users and their permissions), and Audit (reviewing access logs to ensure security). These are crucial for ensuring only authorized users can access the resources they need and to track and manage access effectively.

Answer 18

A reference monitor is a security mechanism that controls access to objects (resources) in a system. It acts as a guard, ensuring that subjects (users, processes) can only access objects according to a defined security policy. It is a key component of the enforcement mechanism in an access control system.

Answer 19

1. Complete Mediation: 1.1 Every access to every object must be checked by the reference monitor. 1.2 This prevents any bypassing of security checks. 1.3Importance: Ensures that no unauthorized access can occur, regardless of the request. 2. Tamperproof: 2.1 The reference monitor itself must be protected from modification. 2.2 Untrusted processes cannot alter its logic or the access control policy it enforces. 2.3 Importance: Maintains the integrity of the access control system; if it's compromised, the entire system is vulnerable. 3. Verifiable: 3.1 The reference monitor's code and logic should be simple enough to be tested and formally verified. 3.2 This ensures it functions correctly and enforces the policy as intended. 3.3 Importance: Provides assurance that the security mechanism is reliable and trustworthy.

Answer 20

Example: A user (subject) wants to read a file (object). 1. Interface: 1.1 The user's request (e.g., a system call) is received by the reference monitor's interface. 1.2 This interface defines how requests are submitted to the reference monitor. 2. Authorization Module: 2.1 The authorization module takes the request and determines what checks need to be performed. 2.2 It maps the user to a subject label, the file to an object label, and the "read" action to a specific operation. 2.3 It then formulates a query for the policy store. 3.Policy Store: 3.1 The policy store holds the access control policy. 3.2 It receives the query from the authorization module (e.g., "Can user X read file Y?"). 3.3 It returns a decision (yes or no) based on the policy. The reference monitor then allows or denies the file read operation based on the policy store's decision.

Answer 21

The protection state describes the current set of permissions and access rights in a system. It defines what operations subjects (users, processes) can perform on objects (files, devices). It's a snapshot of the system's security configuration at a given time.

Answer 22

1. Structure: 1.1 A table where rows represent subjects (e.g., users, processes). 1.2 Columns represent objects (e.g., files, resources). 1.3 Each cell (intersection of a row and column) contains the set of operations a subject can perform on an object. 2. Purpose: 2.1 Provides a clear and concise way to visualize and manage access rights. 2.2 Helps in defining and enforcing security policies.

Answer 23

1. Limitations: 1.1 Size: Can become very large and unwieldy in systems with many subjects and objects. 1.2 Dynamic Changes: Difficult to manage frequent changes like user creation/deletion or file creation/deletion. 1.3 Complexity: Managing access rights becomes complex as the system grows. 2. Mitigation Strategies: 2.1 Access Control Lists (ACLs): Store permissions with objects rather than in a matrix. 2.2 Capability Lists: Store permissions with subjects. 2.3 Role-Based Access Control (RBAC): Group permissions into roles to simplify management. 2.4 Attribute-Based Access Control (ABAC): Use attributes for more flexible and context-aware permissions.

Answer 24

1. Mandatory Access Control (MAC): 1.1 Centralized control by a system administrator. 1.2 Access decisions based on security labels assigned to subjects and objects. 1.3 Enforces a strict, system-wide policy. 2. Discretionary Access Control (DAC): 2.1 Decentralized control; resource owners have control over who accesses their resources. 2.2 Access decisions based on user identities and permissions. 2.3 More flexible, allows for individual user preferences. 3. Comparison: 3.1 MAC emphasizes security and control 3.2 DAC emphasizes flexibility and user autonomy

Answer 25

MAC: 1. Benefits: High security, consistency, and enforcement of the principle of least privilege. 2. Drawbacks: Rigid, less flexible, and high administrative overhead. DAC: 1. Benefits: Flexible, easy to implement, and less administrative overhead. 2. Drawbacks: Less secure, potential for inconsistent policies, and difficult to scale.

Answer 26

MAC: 1. Military or government systems with high-security requirements. 2. Any system where confidentiality and integrity are paramount and user discretion is limited. 3. Reasoning: MAC's centralized control and label-based system ensure that information flow is strictly controlled and protected. DAC: 1. Personal computer systems or small office environments. 2. File-sharing systems where users need to easily manage access to their own data. 3. Reasoning: DAC's flexibility and ease of use make it suitable for scenarios where users need autonomy over their resources.

Answer 27

Principles: 1. Access permissions are associated with roles, not directly with users. 2. Users are assigned to roles. 3. Role assignments can change, but permissions associated with roles typically remain static. Components: 1. Users: Individuals who interact with the system. 2. Roles: Job functions or titles that define a set of permissions. 3. Permissions: Access rights to resources. 4. Role Assignments: The mapping of users to roles.

Answer 28

ABAC: 1. Access is granted based on attributes of the user, the resource, and the environment. 2. Attributes are characteristics or properties (e.g., user's department, resource sensitivity, time of day, location). 3. Policies are defined using these attributes. Flexibility Compared to RBAC: 1. Granularity: ABAC allows for finer-grained control than RBAC. 2. Context-Awareness: ABAC can incorporate contextual information (e.g., time, location). 3. Dynamic Policies: ABAC policies can be more easily adapted to changing requirements.

Answer 29

RBAC: 1. Advantages: Centralized management, intuitive policies, and easy maintenance in static environments. 2. Disadvantages: Not suitable for granular policies, can become complex in dynamic environments, and limited scope. ABAC: 1. Advantages: High flexibility, context-aware, fine-grained control, and well-suited for cloud environments. 2. Disadvantages: Requires a strong foundation and can be more complex to implement initially. Circumstances for ABAC over RBAC: 1. Cloud computing: Need for dynamic, context-aware policies. 2. Healthcare: Fine-grained control over patient data based on attributes like doctor specialty and patient consent. 3. Finance: Complex regulations requiring attribute-based access (e.g., access based on transaction amount, user location, time of day).

Answer 30

Simple-Security Property: 1. A subject cannot read data at a higher security level. 2. "No read up." 3. Significance: Prevents unauthorized disclosure of sensitive information. Security Property: 1. A subject cannot write data to a lower security level. 2. "No write down." 3. Significance: Prevents compromised subjects from leaking sensitive information to less secure areas.

Answer 31

Trojan Horse: 1. A malicious program disguised as legitimate software. 2. Users are tricked into installing it. Threats: 1. Data theft: Can steal sensitive information. 2. Data modification: Can alter or delete data. 3. System compromise: Can provide attackers with unauthorized access.

Answer 32

1. Principle of Least Privilege: Limits the damage a Trojan horse can do by restricting the user's privileges. 2. Mandatory Access Control (MAC): Can prevent a Trojan horse from accessing or writing to files outside the user's security level. 3. Regular Audits: Help detect unauthorized access or changes to files. 4. Strong Authentication: Makes it harder for attackers to use stolen credentials to install Trojan horses.

Answer 33

Operating systems integrate access control into their core functions. Key Components: 1. Kernel: The core of the OS, responsible for enforcing access control. 2. File System: Manages file permissions (e.g., DAC in many systems). 3. Memory Management: Controls access to memory segments. 4. Process Management: Manages process privileges. Interaction: 1. When a process tries to access a resource (e.g., open a file), the OS kernel intercepts the request. 2. The kernel's reference monitor checks if the access is allowed based on the system's access control policy. 3. The kernel then either grants or denies the request.

Answer 34

The kernel is the central authority for access control. It has complete control over system resources. It must be tamperproof to prevent bypassing of access control. The kernel enforces the principle of least privilege to limit the potential damage from security breaches. It acts as a reference monitor, ensuring all access requests are validated.

Answer 35

Challenges: 1. Complexity: Modern OSs are very complex, with many interacting components. 2. Performance Overhead: Access control checks can add overhead. 3. Compatibility: Maintaining compatibility with existing applications. 4. Evolving Threats: OSs must adapt to new security

Answer 36

Protection: security goals are met in the presence of [trusted subjects] Security: security goals are met in the presence of [potentially malicious subjects]

Access Control Flashcards

Main Concepts and Practice Questions