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Oracle® Database Security Guide
12c Release 1 (12.1)

E48135-09
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21 Introduction to Auditing

This chapter contains:

Note:

This part describes how to use pure unified auditing, in which all audit records are centralized in one place. If you have not yet migrated to use unified auditing, then see Oracle Database Upgrade Guide. Be aware that the upgrade process itself does not automatically enable unified auditing. You must manually migrate to unified auditing, as described in Oracle Database Upgrade Guide.

See Also:

"Guidelines for Auditing" for general guidelines to follow for auditing your system

What Is Auditing?

Auditing is the monitoring and recording of configured database actions, from both database users and nondatabase usersFoot 1 . You can base auditing on individual actions, such as the type of SQL statement executed, or on combinations of data that can include the user name, application, time, and so on. You can configure auditing for both successful and failed activities, and include or exclude specific users from the audit. In a multitenant environment, you can audit individual actions of the pluggable database (PDB) or individual actions in the entire multitenant container database (CDB). In addition to auditing the standard activities the database provides, auditing can include activities from Oracle Database Real Application Security, Oracle Recovery Manager, Oracle Data Pump, Oracle Data Mining, Oracle Database Vault, Oracle Label Security, and Oracle SQL*Loader direct path events. Auditing is enabled by default. All audit records are written to the unified audit trail in a uniform format and are made available through the UNIFIED_AUDIT_TRAIL view. These records reside in the AUDSYS schema. The audit records are stored in the SYSAUX tablespace by default. Oracle recommends that you configure a different tablespace for the unified audit trail. For example, you can create a tablespace called SYSAUD with pre-created sized (1 GB) extents for the audit trail tables. To set the new audit trail location, use the DBMS_AUDIT_MGMT.SET_AUDIT_TRAIL_LOCATION procedure. (For more information about this procedure, see Oracle Database PL/SQL Packages and Types Reference.)

You can configure auditing by using any of the following methods:

Oracle recommends that you audit your databases. Auditing is an effective method of enforcing strong internal controls so that your site can meet its regulatory compliance requirements, as defined in the Sarbanes-Oxley Act. This enables you to monitor business operations, and find any activities that may deviate from company policy. Doing so translates into tightly controlled access to your database and the application software, ensuring that patches are applied on schedule and preventing ad hoc changes. By creating effective audit policies, you can generate an audit record for audit and compliance personnel. Be selective with auditing and ensure that it meets your business compliance needs.

Why Is Auditing Used?

You typically use auditing to perform the following activities:

  • Enable accountability for actions. These include actions taken in a particular schema, table, or row, or affecting specific content.

  • Deter users (or others, such as intruders) from inappropriate actions based on their accountability.

  • Investigate suspicious activity. For example, if a user is deleting data from tables, then a security administrator can audit all connections to the database and all successful and unsuccessful deletions of rows from all tables in the database.

  • Notify an auditor of the actions of an unauthorized user. For example, an unauthorized user could be changing or deleting data, or the user has more privileges than expected, which can lead to reassessing user authorizations.

  • Monitor and gather data about specific database activities. For example, the database administrator can gather statistics about which tables are being updated, how many logical I/Os are performed, or how many concurrent users connect at peak times.

  • Detect problems with an authorization or access control implementation. For example, you can create audit policies that you expect will never generate an audit record because the data is protected in other ways. However, if these policies generate audit records, then you will know the other security controls are not properly implemented.

  • Address auditing requirements for compliance. Regulations such as the following have common auditing-related requirements:

    • Sarbanes-Oxley Act

    • Health Insurance Portability and Accountability Act (HIPAA)

    • International Convergence of Capital Measurement and Capital Standards: a Revised Framework (Basel II)

    • Japan Privacy Law

    • European Union Directive on Privacy and Electronic Communications

Best Practices for Auditing

Follow these best practices guidelines:

  • As a general rule, design your auditing strategy to collect the amount of information that you need to meet compliance requirements, but focus on activities that cause the greatest security concerns. For example, auditing every table in the database is not practical, but auditing tables with columns that contain sensitive data, such as salaries, is. With both unified and fine-grained auditing, there are mechanisms you can use to design audit policies that focus on specific activities to audit.

  • Periodically archive and purge the audit trail data. See "Purging Audit Trail Records" for more information.

See Also:

"Guidelines for Auditing" for general guidelines to follow for auditing your system

What Is Unified Auditing?

In unified auditing, the unified audit trail captures audit information from the following sources:

  • Audit records (including SYS audit records) from unified audit policies and AUDIT settings

  • Fine-grained audit records from the DBMS_FGA PL/SQL package

  • Oracle Database Real Application Security audit records

  • Oracle Recovery Manager audit records

  • Oracle Database Vault audit records

  • Oracle Label Security audit records

  • Oracle Data Mining records

  • Oracle Data Pump

  • Oracle SQL*Loader Direct Load

The unified audit trail, which resides in a read-only table in the AUDSYS schema in the SYSAUX tablespace, makes this information available in a uniform format in the UNIFIED_AUDIT_TRAIL data dictionary view, and is available in both single-instance and Oracle Database Real Application Clusters environments. In addition to the user SYS, users who have been granted the AUDIT_ADMIN and AUDIT_VIEWER roles can query these views. If your users only need to query the views but not create audit policies, then grant them the AUDIT_VIEWER role.

When the database is writeable, audit records are written to the unified audit trail. If the database is not writable, then audit records are written to new format operating system files in the $ORACLE_BASE/audit/$ORACLE_SID directory.

See Also:

Oracle Database Reference for detailed information about the UNIFIED_AUDIT_TRAIL data dictionary view

Benefits of the Unified Audit Trail

The benefits of a unified audit trail are many:

  • After unified auditing is enabled, it does not depend on the initialization parameters that were used in previous releases. See Table G-1 for a list of these initialization parameters.

  • The audit records, including records from the SYS audit trail, for all the audited components of your Oracle Database installation are placed in one location and in one format, rather than your having to look in different places to find audit trails in varying formats. This consolidated view enables auditors to co-relate audit information from different components. For example, if an error occurred during an INSERT statement, standard auditing can indicate the error number and the SQL that was executed. Oracle Database Vault-specific information can indicate whether this error happened because of a command rule violation or realm violation. Note that there will be two audit records with a distinct AUDIT_TYPE. With this unification in place, SYS audit records appear with AUDIT_TYPE set to Standard Audit.

  • The management and security of the audit trail is also improved by having it in single audit trail.

  • Overall auditing performance is greatly improved. The default mode that unified audit works is Queued Write mode. In this mode, the audit records are batched in SGA queue and is persisted in a periodic way. Because the audit records are written to SGA queue, there is a significant performance improvement. To set the performance mode, see "Auditing Activities with Unified Audit Policies and the AUDIT Statement".

  • You can create named audit policies that enable you to audit the supported components listed at the beginning of this section, as well as SYS administrative users. Furthermore, you can build conditions and exclusions into your policies.

Checking if Your Database Has Migrated to Unified Auditing

You can find if your database has been migrated to unified auditing by querying the V$OPTION dynamic view as follows:

SELECT VALUE FROM V$OPTION WHERE PARAMETER = 'Unified Auditing';

PARAMETER         VALUE
----------------  ----------
Unified Auditing  TRUE

Enter Unified Auditing in the case shown in this query.

This output shows that unified auditing is enabled. If unified auditing has not been enabled, then the output is FALSE.

See Also:

"Disabling Unified Auditing" if you must disable unified auditing

Mixed Mode Auditing

This section contains:

About Mixed Mode Auditing

When you create a new database, by default the database uses mixed mode auditing, which enables both traditional (that is, the audit facility from releases earlier than Release 12c) and the new audit facilities (unified auditing). This chapter describes how to use pure unified auditing only.

You can enable the database in either of these two modes: the mixed mode auditing or pure unified auditing mode. Even though the features of unified auditing are enabled in both these modes, there are differences between them. In mixed mode, you can use the new unified audit facility alongside the traditional auditing facility. In pure unified auditing, you only use the unified audit facility.

Table 21-1 summarizes the features of these two modes and how you enable them.

Table 21-1 Differences Between MIxed Mode Audting and Pure Unified Auditing

Mode Features How to Enable

Mixed mode auditing

Has both traditional and unified auditing

Enable any unified audit policy. There is no need to restart the database.

Pure unified auditing

Has only unified auditing

Link the oracle binary with uniaud_on, and then restart the database. Oracle Database Upgrade Guide describes how to enable pure unified auditing.


Mixed mode is intended to introduce unified auditing, so that you can have a feel of how it works and what its nuances and benefits are. Mixed mode enables you to migrate your existing applications and scripts to use unified auditing. Once you have decided to use pure unified auditing, you can relink the oracle binary with the unified audit option turned on and thereby enable it as the one and only audit facility the Oracle database runs. If you decide to revert back to mixed mode, you can.

As in previous releases, the traditional audit facility is driven by the AUDIT_TRAIL initialization parameter. Only for mixed mode auditing, you should set this parameter to the appropriate traditional audit trail. This traditional audit trail will then be populated with audit records, along with the unified audit trail.

When you upgrade your database to the current release, traditional auditing is preserved, and the new audit records are written to the traditional audit trail. After you complete the migration (as described in Oracle Database Upgrade Guide), the audit records from the previous release are still available in those audit trails. You then can archive and purge these older audit trails by using the DBMS_AUDIT_MGMT PL/SQL procedures, based on your enterprise retention policies.

See Also:

How Database Creation Determines the Type of Auditing You Have Enabled

Unified auditing uses the $ORACLE_BASE/audit directory as the location for the new format operating system files. For newly created databases, mixed mode auditing is enabled by default through the predefined policy ORA_SECURECONFIG.

To start using unified auditing, you must enable at least one unified audit policy, and to stop using it, disable all unified audit policies.

See Also:

"Secure Options Predefined Unified Audit Policy" for more information about the ORA_SECURECONFIG policy

Capabilities of Mixed Mode Auditing

Mixed mode auditing provides the following capabilities:

  • It enables the use of all existing auditing initialization parameters: AUDIT_TRAIL, AUDIT_FILE_DEST, AUDIT_SYS_OPERATIONS, and AUDIT_SYSLOG_LEVEL.

  • It writes mandatory audit records only to the traditional audit trails.

  • It bases standard audit records on the standard audit configuration, and writes these records to the audit trail designated by the AUDIT_TRAIL initialization parameter.

    However, be aware that standard audit trail records are also generated based on unified audit policies and only these audit records are written to the unified audit trail. The standard audit records generated as a result of unified audit policies follow the semantics of unified audit policy enablement.

  • Administrative user sessions generate SYS audit records. These records are written if the AUDIT_SYS_OPERATIONS initialization parameter is set to TRUE. This process writes the records only to the traditional audit trails. However, when unified audit policies are enabled for administrative users, these unified audit records are also written to unified audit trail.

  • The format of the audit records that are written to traditional audit trails remains the same as in Oracle Database 11g Release 2.

  • By default, Oracle Database writes unified audit records to system global area (SGA) queues. In other words, it writes the records periodically, not immediately. You can control how often the audit records are written. See "Writing the Unified Audit Trail Records to the AUDSYS Schema" for more information.

  • The performance cost of writing an audit record is equivalent to the sum of the times required for generating and writing an audit record to the traditional audit trail and the unified audit trail.

  • Mixed mode auditing provides a glance of the unified audit mode features. Oracle recommends that you migrate to unified audit mode once you are comfortable with the new style of audit policies and audit trail. To migrate to unified auditing, see Oracle Database Upgrade Guide.

Who Can Perform Auditing?

In order to perform any kind of auditing, you must be granted one of the following roles:

  • AUDIT_ADMIN role. This role enables you to create unified and fine-grained audit policies, use the AUDIT and NOAUDIT SQL statements, view audit data, and manage the audit trail administration. Grant this role only to trusted users.

  • AUDIT_VIEWER role. This role enables users to view and analyze audit data. The kind of user who needs this role is typically an external auditor.

Note:

In previous releases, users were allowed to add and remove audit configuration to objects in their own schemas without any additional privileges. This ability is no longer allowed.

Using Auditing in a Multitenant Environment

You can apply audit settings to individual PDBs or to the CDB as a whole, depending on the type of policy. In a Multitenant environment, each PDB, including the root, has own unified audit trail.

See the following sections for more information:

See Also:

Oracle Database Concepts for information about the common audit configurations in a multitenant environment

Auditing in a Distributed Database

Auditing is site autonomous. A database instance audits only the statements issued by directly connected users. A local Oracle Database node cannot audit actions that take place in a remote database.



Footnote Legend

Footnote 1: "Nondatabase users" refers to application users who are recognized in the database using the CLIENT_IDENTIFIER attribute. To audit this type of user, you can use a unified audit policy condition, a fine-grained audit policy, or Oracle Database Real Application Security.