|Oracle7 Server Concepts Manual||
This chapter discusses the auditing feature of Oracle. It includes:
The selective auditing of SQL statements with respect to only the type of statement, not the specific objects on which it operates. Statement auditing options are typically broad, auditing the use of several types of related actions per option; for example, AUDIT TABLE, which tracks several DDL statements regardless of the table on which they are issued. You can set statement auditing to audit selected users or every user in the database.
The selective auditing of the use of powerful system privileges to perform corresponding actions, such as AUDIT CREATE TABLE. Privilege auditing is more focused than statement auditing, auditing only the use of the target privilege. You can set privilege auditing to audit a selected user or every user in the database.
The selective auditing of specific statements on a particular schema object, such as AUDIT SELECT ON EMP. Object auditing is very focused, auditing only a specific statement on a specific object. Object auditing always applies to all users of the database.
You can set audit options to determine the type of audit information that is collected.
The database audit trail is a single table named AUD$ in the SYS schema of each Oracle database's data dictionary. Several predefined views are provided to help you use this information. Instructions for creating and using these views are included in the Oracle7 Server Administrator's Guide.
Depending on the events audited and the auditing options set, the audit trail records can contain different types of information. The following information is always included in each audit trail record, provided that the information is meaningful to the particular audit action:
This describes the operation performed or attempted. The AUDIT_ACTIONS data dictionary table contains a list of these codes and their descriptions.
This describes any system privileges used to perform the operation. The SYSTEM_PRIVILEGE_MAP table lists all of these codes and their descriptions.
This describes the result of the attempted operation. Successful operations return a value of zero, while unsuccessful operations return the Oracle error code describing why the operation was unsuccessful. These codes are listed in Oracle7 Server Messages.
Assuming auditing is enabled in the database, an audit record is generated during the execute phase of statement execution.
Note: If you are not familiar with the different phases of SQL statement processing and shared SQL, see Chapter 11, "SQL and PL/SQL", for background information concerning the following discussion.
SQL statements inside PL/SQL program units are individually audited, as necessary, when the program unit is executed.
The generation and insertion of an audit trail record is independent of a user's transaction; therefore, if a user's transaction is rolled back, the audit trail record remains committed.
Note: Audit records are never generated by sessions established by the user SYS or connections as INTERNAL. Connections by these users bypass certain internal features of Oracle to allow specific administrative operations to occur (for example, database startup, shutdown, recovery, and so on).
An audit record is generated that details the OS user starting the instance, his terminal identifier, the date and time stamp, and whether database auditing was enabled or disabled. This is audited into the OS audit trail because the database audit trail is not available until after startup has successfully completed. Recording the state of database auditing at startup further prevents an administrator from restarting a database with database auditing disabled so that they are able to perform unaudited actions.
An audit record is generated that details the OS user shutting down the instance, her terminal identifier, the date and time stamp.
Connections to the database as INTERNAL
An audit record is generated that details the OS user connecting to Oracle as INTERNAL. This provides accountability of users connected as INTERNAL.
On operating systems that do not make an audit trail accessible to Oracle, these audit trail records are placed in an Oracle audit trail file in the same directory as background process trace files.
Additional Information: See your operating system-specific Oracle documentation for more information about the operating system audit trail.
Additional Information: See your platform-specific Oracle documentation to see if this feature has been implemented on your operating system.
Trusted Oracle and Oracle allow certain actions that are always audited to continue even when the operating system audit trail, or the operating system file containing audit records, is unable to record the audit record. The normal cause of this is that the operating system audit trail, or the file system, is full and unable to accept new records.
When configured with OS auditing, system administrators should ensure that the audit trail or the file system does not fill completely. Most operating systems provide extensive measures to provide administrators with sufficient information and warning to ensure this does not occur. Furthermore, configuring auditing to use the database audit trail removes this vulnerability, as the Oracle Server prevents audited events from occurring if the audit trail is unable to accept the audit record for the statement.
You can audit the use of any system privilege. In all cases of privilege auditing, owner privileges and object privileges are checked before the use of system privileges. If these other privileges suffice to permit the action, the action is not audited. If similar statement and privilege audit options are both set, only a single audit record is generated. For example, if the statement option TABLE and the system privilege CREATE TABLE are both audited, only a single audit record is generated each time a table is created.
Privilege auditing is more focused than statement auditing because each option audits only specific types of statements, not a related list of statements. For example, the statement auditing option TABLE audits CREATE TABLE, ALTER TABLE, and DROP TABLE statements, while the privilege auditing option CREATE TABLE audits only CREATE TABLE statements, since only the CREATE TABLE statement requires the CREATE TABLE privilege.
Privilege auditing can be broad, and audit the activities of all database users, or focused, and audit only the activities of a select list of database users.
You can audit statements that reference tables, views, sequences, standalone stored procedures and functions, and packages (procedures in packages cannot be audited individually). Notice that statements that reference clusters, database links, indexes, or synonyms are not audited directly.
You can, however, audit access to these objects indirectly by auditing the operations that affect the base table. Object audit options are always set for all users of the database; these options cannot be set for a specific list of users. Oracle provides a mechanism for setting default object audit options for all auditable schema objects.
As an illustration of this situation, consider the following series of SQL statements:
AUDIT SELECT ON emp;
CREATE VIEW emp_dept AS
SELECT empno, ename, dname
FROM emp, dept
WHERE emp.deptno = dept.deptno;
AUDIT SELECT ON emp_dept;
SELECT * FROM emp_dept;
As a result of the query on EMP_DEPT, two audit records are generated: one for the query on the EMP_DEPT view and one for the query on the base table EMP (indirectly via the EMP_DEPT view). The query on the base table DEPT does not generate an audit record because the SELECT audit option for this table is not enabled. All audit records pertain to the user that queried the EMP_DEPT view.
The audit options for a view or procedure are determined when the view or procedure is first used and placed in the shared pool. These audit options remain set until the view or procedure is flushed from, and subsequently replaced in, the shared pool. Auditing an object invalidates that object in the cache and causes it to be reloaded. Any changes to the audit options of base objects are not observed by views and procedures in the shared pool. Continuing with the above example, if auditing of SELECT statements is turned off for the EMP table, use of the EMP_DEPT view would no longer generate an audit record for the EMP table.
You can audit an unsuccessful statement execution only if a valid SQL statement is issued but fails because of lack of proper authorization or because it references a non-existent object. Statements that failed to execute because they simply were not valid cannot be audited. For example, an enabled privilege auditing option set to audit unsuccessful statement executions audits statements that use the target system privilege but have failed for other reasons (for example, CREATE TABLE is set, but a CREATE TABLE statement fails due to lack of quota for the specified tablespace).
Using either form of the AUDIT command, you can include
To demonstrate how the BY SESSION option allows the generation of audit records, consider the following two examples.
Example 1 Assume the following:
Example 2 Alternatively, assume the following:
Although you can use the BY SESSION option when directing audit records to the operating system audit trail, this generates and stores an audit record each time an access is made. Therefore, in this auditing configuration, BY SESSION is equivalent to BY ACCESS.
Note: A session is the time between when a user connects to and disconnects from an Oracle database.
Example Assume the following:
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