I am receiving the /var/log/secure logs from my linux forwarder I am trying to create a search string that can detect when a user has added any user to sudo access. For example, I'd like to be able to detect when user1 adds user2 to the wheel group in order to give user2 sudo access.
I used this to find my user using visudo to add a user to wheel. I am sure there a few different conditions that you'd hunt for...
index=* host=* source=/var/log/secure visudo OR usermod
Replace with your commands or logic accordingly.
I use the nix TA found here to ensure my field extractions (Splunk PS configs, you can use whatever you like): https://bitbucket.org/SPLServices/splunk_ta_nix/src
While on the topic of authentication and privilege, check out this wicked auth app by @dshpritz
https://splunkbase.splunk.com/app/3639/