Monday, December 13, 2010

ACCESS CONTROL FACTS FROM SECURITY POINT OF VIEW

* Access control is the ability to permit or deny the privileges that users have when accessing resources on a network or computer. Access control involves three entities:

=> Objects are the data, applications, systems, networks, and physical space.

=>Subjects are the users, applications, or processes that need access to objects.

=>The access control system includes the policies, procedures, and technologies that are implemented to control a subject's access to an object.

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* Access control includes the following processes:

=> Identification identifies the subject. Examples include a username or a user ID number.

=> Authentication is the process of validating a subject's identity. It includes the identification process, the user providing input to prove identity, and the system accepting that input as valid.

=> Authorization is the granting or denying a subject's access to an object based on the level of permissions or the actions allowed on the object.

=>Auditing (also referred to as accounting) is maintaining a record of a subject's activity within the information system.
Note: Authentication, authorization, and auditing are known as the AAA of access control.

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* An access control policy defines the steps and measures that are taken to control access to objects by subjects. Access controls can be classified according to the function they perform:

=> Preventive access controls deter intrusion or attacks, for example, separation of duties or dual-custody processes.

=> Detective access controls search for details about the attack or the attacker, for example, intrusion detection systems.

=> Corrective access controls implement short-term repairs to restore basic functionality following an attack.

=> Deterrent access controls discourage continued or escalations of attacks during an attack.

=> Recovery access controls restore the system to normal operations after the attack and short-term stabilization period.

=> Compensative access controls are alternatives to primary access controls.
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* Access control measures can also be classified based on how they restrict or control access:

=> Administrative controls are policies that describe accepted practices. Examples are directive policies and employee awareness training.

=> Technical controls are computer mechanisms that restrict access.
Examples are encryption, one-time passwords, access control lists, and firewall rules.

=> Physical controls restrict physical access. Examples are perimeter security, site location, networking cables, and employee segregation.


On a computer network, a directory service is an example of a technical access control system that you use to manage and enforce access control policies. Examples of directory services are:

=> Active Directory for Microsoft Windows networks.

=> Novell's eDirectory for NetWare, Linux, and Windows networks.

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* Within the directory service:

=> A user account is created for each subject.
Identification is performed during logon by supplying a valid user account name.

=> Authentication is performed during logon by supplying the password or other requirements for proving identity.

=> Authorization to use network resources, such as files, printers, or computers, is controlled by identifying permissions or rights.

=> Auditing is performed by the operating system as it tracks actions taken by subjects on objects.

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