| Preventing non-privileged users from executing privileged functions mitigates the risk that unauthorized individuals or processes may gain unnecessary access to information or privileges.
System documentation should include a definition of the functionality considered privileged.
Depending on circumstances, privileged functions can include, for example, establishing accounts, performing system integrity checks, or administering cryptographic key management activities. Non-privileged users are individuals that do not possess appropriate authorizations. Circumventing intrusion detection and prevention mechanisms or malicious code protection mechanisms are examples of privileged functions that require protection from non-privileged users.
A privileged function in PostgreSQL/database context is any operation that modifies the structure of the database, its built-in logic, or its security settings. This would include all Data Definition Language (DDL) statements and all security-related statements. In an SQL environment, it encompasses, but is not necessarily limited to:
There may also be Data Manipulation Language (DML) statements that, subject to context, should be regarded as privileged. Possible examples include:
DELETE affecting more than n rows, for some n, or
DELETE without a WHERE clause;
UPDATE affecting more than n rows, for some n, or
UPDATE without a WHERE clause;
any SELECT, INSERT, UPDATE, or DELETE to an application-defined security table executed by other than a security principal.
Depending on the capabilities of PostgreSQL and the design of the database and associated applications, the prevention of unauthorized use of privileged functions may be achieved by means of DBMS security features, database triggers, other mechanisms, or a combination of these.
However, the use of procedural languages within PostgreSQL, such as pl/R and pl/Python, introduce security risk. Any user on the PostgreSQL who is granted access to pl/R or pl/Python is able to run UDFs to escalate privileges and perform unintended functions. Procedural languages such as pl/Perl and pl/Java have "untrusted" mode of operation, which do not allow a non-privileged PostgreSQL user to escalate privileges or perform actions as a database administrator. |