Authorization

Authorization is a process of assigning authenticated subjects access and the
right to carry out specific operations, depending upon their preconfigured access rights and permissions outlined in an access criteria. An access criteria is
developed by the administrator, or security officer, to support and carry out the
organization’s security policy. A criteria can be based on one or both of the following items:
•Clearance The security level the subject holds, which directly dictates
the objects that are accessible to it.
•Need-to-know The formal access level approved that correlates to
what information should and should not be available to a subject.
Mandatory access control (MAC) environments use clearances, classifications, and need-to-know to determine if a subject can access an object and what
operations can be carried out. Discretionary access control (DAC) environments use access control lists (ACLs), which are developed based strictly on the
subject’s need-to-know. MAC and DAC environments are described in the “Access
Control Models and Techniques” section of this chapter.
It is important to only give the subject access to the objects (resources, devices,
and information) that are required for it to complete its tasks. This concept is referred to asleast privilege. This reduces the possibility of fraud and damaging
accidents by limiting access to objects based purely on business needs.
It is best for mechanisms that are making access decisions to default to “no
access.”This means that if a subject is not explicitly allowed, it is implicitly denied.
In other words, if I don’t tell you specifically you can do something, you can do
nothing.
If a task must be completed by two or more individuals coming together to
carry out their piece of the task, it is referred to as dual control. For example, in a
cryptographic key recovery technology, the master key needed to decrypt a lost
key is usually split up into two or more pieces and each piece is given to an individual. If this master key needs to be reconstructed to recover a lost key, each individual with a piece of the key must submit their portion, which the system
combines to create the original master key. This is dual control, because it requires more than one person to complete an important task.