First of all, thanks for the Ultimate Security Checker -plugin, it's awesome! But I think this should be fixed...
Files & folders permission check gives a warning:
"Insufficient rights on wp-content folder!"
I assume it checks that wp-content has permissions 777, as the 'How to Fix' section says:
/wp-content/ should be writeable for all(777).
This is not good for security. 755 is what it should be. If some plugin, or something else, (temporarily) needs 777 if can be changed when configuring the plugin and then back. This check should be removed from the Ultimate Security Check, or change it to 755.
Also, (for the "How to Fix" part: for most blogs 644 does not work for /wp-admin/ and /wp-includes/ - Codex says (correctly) that by default all directories should be 755. (Hardening WordPress: File Permissions)