DATABASE SECURITY - Database Design and Development: An Essential Guide for IT Professionals - page 501

SPECIAL SECURITY CONSIDERATIONS
We have covered several topics on database security so far. You know the common
types of security threats. You have explored solution options. You have reviewed
the two major approaches to database access control—discretionary and manda-
tory. Before we finish our discussion of the significant topics, we need to consider
just a few more.
In our discussion on granting access privileges, we have been referring to indi-
vidual users or user groups that need access privileges. Who are these users, and
how do you identify them to the database system? This is an important question we
need to address. Another obvious question is, Where is the DBA in all of these data-
base security provisions, and what is the role of the DBA? Finally, we will inspect
what are known as statistical databases and consider special security problems
associated with these.
Authorization
The security mechanism protecting a database system is expected to prevent users
from performing database operations unless they are authorized to do so. Autho-
rization for data access implies access control. We have discussed discretionary and
mandatory access control approaches. Let us now complete the discussion by touch-
ing on a few remaining topics.
Profiles To authorize a subject that may be a user, a group of users, a program,
or a module, an account is assigned to the subject. Let us confine our discussion to
a subject who is a user. User Samantha Jenkins is eligible to have access to the
human resources database. So first, Jenkins must be assigned an account or user-
identification.
The DBMS maintains a user profile for each user account. The profile for Jenkins
includes all the database objects such as tables, views, rows, and columns that she
is authorized to access. In the user profile, you will also find the types of access
privileges such as read, update, insert, and delete granted to Jenkins.
Alternatively, the DBMS may maintain an object profile for each database object.
An object profile is another way of keeping track of the authorizations. For example,
in the object profile for the EMPLOYEE table, you will find all the user accounts
that are authorized to access the table. Just like a user profile, an object profile also
indicates the types of access privileges.
Authorization Rules The user profile or the object profile stipulates which user
can access which database object and in what way. These are the authorization rules.
By examining these rules, the DBMS determines whether a specific user may be
permitted to perform the operations of read, update, insert, or delete on a particu-
lar database object. You have already looked at an example of an authorization
matrix in Figure 16-4. This matrix tends to be exhaustive and complex in a large
database environment.
Many DBMSs do not implement elaborate information matrices as presented in
Figure 16-4 to enforce authorization rules. Instead, they adopt simpler versions to
implement authorization rules. Authorization rules may be represented as an autho-