RHEL6: All Up in Your Face with Auditd

Strongbad2kqAuditd is the userland piece of the RHEL audit tool suite. When its up and running, audit messages sent by the kenel will be send to log files that you have configured. By default, only a small and limited number of messages will be picked up by Auditd; these are mostly messages related to authentication and authorization.

Auditd has three main config files as shown below

  • /etc/sysconfig/auditd – basic configuration options
  • /etc/audit/auditd.conf – main config file
  • /etc/audit/audit.rules – auditing rules

Auditd and Syslog:

Its possible to send audit messages to a syslog. By setting active=yes in /etc/audisp/plugins.d/syslog.conf you can send all your audit messages to syslog. If your system is setup to log to a remote syslog server, then your audit messages will go along for the ride as well. Note that you can also send audit messages to a remote logging server via native audit protocol over TCP. I am not going to go into this option, but I want to make sure that we are aware that it exists.

 

Looking for Audit Events in All the Wrong Places:

Auditd includes a handy-dandy tool for searching audit logs. Ausearch. You can check out all your current audit log messages using the command below.

[root@ip-172-31-21-28 ~]# ausearch -l

Viewing audit logs in their raw format can be accomplished with the command below

[root@ip-172-31-21-28 ~]# ausearch –raw

The -a option allows you to search by audit event ids

[root@ip-172-31-21-28 ~]# ausearch -a 282

Auditd also includes ausearch, which allows you to get a quick summary of audit events, rather than trying to view massive audit logs. Usage and output shown below.

root@ip-172-31-21-28 ~]# aureport

Summary Report
======================
Range of time in logs: 07/17/2014 10:21:36.438 – 07/17/2014 19:52:49.556
Selected time for report: 07/17/2014 10:21:36 – 07/17/2014 19:52:49.556
Number of changes in configuration: 4
Number of changes to accounts, groups, or roles: 24
Number of logins: 20
Number of failed logins: 4
Number of authentications: 75
Number of failed authentications: 3
Number of users: 3
Number of terminals: 18
Number of host names: 19
Number of executables: 14
Number of files: 0
Number of AVC's: 10
Number of MAC events: 20
Number of failed syscalls: 10
Number of anomaly events: 0
Number of responses to anomaly events: 0
Number of crypto events: 244
Number of keys: 0
Number of process IDs: 203
Number of events: 1132

You can also use aureport and ausearch together. Simliar to the powerfull partnership between Batman and Robin, these two tools complement each other in ways that you can only imagine. Check out my sexy bits below.

[root@ip-172-31-21-28 ~]# ausearch –start today –raw | aureport

Summary Report
======================
Range of time in logs: 07/17/2014 10:21:36.438 – 07/17/2014 20:01:01.911
Selected time for report: 07/17/2014 10:21:36 – 07/17/2014 20:01:01.911
Number of changes in configuration: 4
Number of changes to accounts, groups, or roles: 24
Number of logins: 20
Number of failed logins: 4
Number of authentications: 75
Number of failed authentications: 3
Number of users: 3
Number of terminals: 18
Number of host names: 19
Number of executables: 14
Number of files: 0
Number of AVC's: 10
Number of MAC events: 20
Number of failed syscalls: 10
Number of anomaly events: 0
Number of responses to anomaly events: 0
Number of crypto events: 244
Number of keys: 0
Number of process IDs: 205
Number of events: 1144

Want to know another cool tool that is part of auditd? I know, its a lot to take in at one time, but I am sure that you can handle it. Using autrace you can trace and investigate system calls made by a process. 

Want to see everything that nslookup is doing? Then run the command below.

[root@ip-172-31-21-28 ~]# autrace /usr/bin/nslookup google.com

This will output a pid for you to trace with ausearch.

Trace complete. You can locate the records with 'ausearch -i -p 3359'

 

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