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User Domain Policies.

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Presentation on theme: "User Domain Policies."— Presentation transcript:

1 User Domain Policies

2 Chapter 9: User Domain Policies

3 User Domain Policies Typical domain user and account types

4 User Domain Policies Security personnel responsibilities

5 User Domain Policies Access Control
Mandatory access control (MAC) refers to a type of access control by which the operating system constrains the ability of a subject or initiator to access or generally perform some sort of operation on an object or target. In practice, a subject is usually a process or thread; objects are constructs such as files, directories, TCP/UDP ports, shared memory segments, IO devices etc. Subjects and objects each have a set of security attributes. Whenever a subject attempts to access an object, an authorization rule enforced by the operating system kernel examines these security attributes and decides whether the access can take place. Any operation by any subject on any object is tested against the set of authorization rules (aka policy) to determine if the operation is allowed. A database management system, in its access control mechanism, can also apply mandatory access control; in this case, the objects are tables, views, procedures, etc.

6 User Domain Policies Access Control
Discretionary access control (DAC) is a type of access control defined by the Trusted Computer System Evaluation Criteria "as a means of restricting access to objects based on the identity of subjects and/or groups to which they belong. The controls are discretionary in the sense that a subject with a certain access permission is capable of passing that permission (perhaps indirectly) on to any other subject (unless restrained by mandatory access control)". Discretionary access control is commonly discussed in contrast to mandatory access control (MAC, sometimes termed non-discretionary access control). Occasionally a system as a whole is said to have "discretionary" or "purely discretionary" access control as a way of saying that the system lacks mandatory access control. On the other hand, systems can be said to implement both MAC and DAC simultaneously, where DAC refers to one category of access controls that subjects can transfer among each other, and MAC refers to a second category of access controls that imposes constraints upon the first.

7 User Domain Policies Access Control
Role-based access control (RBAC) is an approach to restricting system access to authorized users. It is used by the majority of enterprises with more than 500 employees, and can implement mandatory access control (MAC) or discretionary access control (DAC). RBAC is sometimes referred to as role-based security. Within an organization, roles are created for various job functions. The permissions to perform certain operations are assigned to specific roles. Members or staff (or other system users) are assigned particular roles, and through those role assignments acquire the computer permissions to perform particular computer-system functions. Since users are not assigned permissions directly, but only acquire them through their role (or roles), management of individual user rights becomes a matter of simply assigning appropriate roles to the user's account; this simplifies common operations, such as adding a user, or changing a user's department.

8 User Domain Policies Access Control
Three primary rules are defined for RBAC: Role assignment: A subject can exercise a permission only if the subject has selected or been assigned a role. Role authorization: A subject's active role must be authorized for the subject. With rule 1 above, this rule ensures that users can take on only roles for which they are authorized. Permission authorization: A subject can exercise a permission only if the permission is authorized for the subject's active role. With rules 1 and 2, this rule ensures that users can exercise only permissions for which they are authorized.

9 User Domain Policies Access Control
The NIST RBAC model is a standardized definition of role based access control. Although originally developed by the National Institute of Standards and Technology, the standard was adopted and is copyrighted and distributed as INCITS by the International Committee for Information Technology Standards (INCITS). The latest version is INCITS It is managed by INCITS committee CS1.

10 User Domain Policies Access Control
Lattice-based access control (LBAC) is a complex access control model based on the interaction between any combination of objects (such as resources, computers, and applications) and subjects (such as individuals, groups or organizations). In this type of label-based mandatory access control model, a lattice is used to define the levels of security that an object may have and that a subject may have access to. The subject is only allowed to access an object if the security level of the subject is greater than or equal to that of the object. Mathematically, the security level access may also be expressed in terms of the lattice (a partial order set) where each object and subject have a greatest lower bound (meet) and least upper bound (join) of access rights.

11 User Domain Policies Access Control
For example, if two subjects A and B need access to an object, the security level is defined as the meet of the levels of A and B. In another example, if two objects X and Y are combined, they form another object Z, which is assigned the security level formed by the join of the levels of X and Y. LBAC is known as a label-based access control (or rule-based access control) restriction as opposed to role-based access control (RBAC). Lattice based access control models were first formally defined by Denning (1976)

12 User Domain Policies Access Control
Bell–LaPadula Model (abbreviated BLP) is a state machine model used for enforcing access control in government and military applications. It was developed by David Elliott Bell and Leonard J. LaPadula, subsequent to strong guidance from Roger R. Schell to formalize the U.S. Department of Defense (DoD) multilevel security (MLS) policy. The model is a formal state transition model of computer security policy that describes a set of access control rules which use security labels on objects and clearances for subjects. Security labels range from the most sensitive (e.g."Top Secret"), down to the least sensitive (e.g., "Unclassified" or "Public").

13 User Domain Policies Access Control
The model defines two mandatory access control (MAC) rules and one discretionary access control (DAC) rule with three security properties: The Simple Security Property - a subject at a given security level may not read an object at a higher security level (no read-up). The ★-property (read "star"-property) - a subject at a given security level must not write to any object at a lower security level (no write-down). The Discretionary Security Property - use of an access matrix to specify the discretionary access control.

14 User Domain Policies Access Control
Biba Model or Biba Integrity Model developed by Kenneth J. Biba in 1977, is a formal state transition system of computer security policy that describes a set of access control rules designed to ensure data integrity. Data and subjects are grouped into ordered levels of integrity. The model is designed so that subjects may not corrupt objects in a level ranked higher than the subject, or be corrupted by objects from a lower level than the subject. In general the model was developed to address integrity as the core principle, which is the direct inverse of the Bell–LaPadula model. The Biba model defines a set of security rules, the first two of which are similar to the Bell-LaPadula model. These first two rules are the reverse of the Bell-LaPadula rules: The Simple Integrity Axiom states that a subject at a given level of integrity must not read an object at a lower integrity level (no read down). The * (star) Integrity Axiom states that a subject at a given level of integrity must not write to any object at a higher level of integrity (no write up). Invocation Property states that a process from below can not request higher access; only with subjects at an equal or lower level.

15 User Domain Policies Access Control
Clark–Wilson integrity model provides a foundation for specifying and analyzing an integrity policy for a computing system. The model is primarily concerned with formalizing the notion of information integrity. Information integrity is maintained by preventing corruption of data items in a system due to either error or malicious intent. An integrity policy describes how the data items in the system should be kept valid from one state of the system to the next and specifies the capabilities of various principals in the system. The model defines enforcement rules and certification rules.

16 User Domain Policies Access Control
The model’s enforcement and certification rules define data items and processes that provide the basis for an integrity policy. The core of the model is based on the notion of a transaction. A well-formed transaction is a series of operations that transition a system from one consistent state to another consistent state. In this model the integrity policy addresses the integrity of the transactions. The principle of separation of duty requires that the certifier of a transaction and the implementer be different entities.

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