The following techniques can help you achieve your organization's security goals while auditing more efficiently.
For as many audit classes as possible, preselect those classes only for users and roles, not system-wide.
Randomly audit only a certain percentage of users at any one time.
If the audit_binfile plugin is active, reduce the disk storage requirements for audit files by filtering, merging, and compressing the files. Develop procedures for archiving the files, for transferring the files to removable media, and for storing the files offline.
Monitor the audit data in real time for unusual behaviors.
audit_syslog plugin – You can extend management and analysis tools that you have already developed to handle the audit records in syslog files.
audit_binfile plugin – You can set up procedures to monitor the audit trail for certain activities. You can write a script to trigger an automatic increase in the auditing of certain users or certain systems in response to detection of unusual events.
For example, you could write a script that does the following:
Monitors the creation of audit files on the audited systems.
Processes the audit files with the tail command.
The piping of the output from the tail -0f command through the praudit command can yield a stream of audit records as the records are generated. For more information, see the tail(1) man page.
Analyzes this stream for unusual message types or other indicators, and delivers the analysis to the auditor.
Alternatively, the script can be used to trigger automatic responses.
Constantly monitors the audit file systems for the appearance of new not_terminated audit files.
Terminates outstanding tail processes when their files are no longer being written to.