Sites that talk about hardening WordPress
http://wpengine.com/blog/wordpress-security-best-practices-white-paper/
http://codex.wordpress.org/Hardening_WordPress
https://yoast.com/wordpress-security/
https://premium.wpmudev.org/blog/keeping-wordpress-secure-the-ultimate-guide/
http://www.woothemes.com/2013/09/improve-your-wordpress-security-with-these-10-tips/
Sites that have plugins that will help with Security and Auditing.
https://wordpress.org/plugins/search.php?type=term&q=audit+log
https://wordpress.org/plugins/sucuri-scanner/