Error message:
sudo: An error occurred on line 19 of /etc/sudo.conf when loading the plug-in "sudoers_policy"
sudo: /usr/libexec/sudo/sudoers.so must only be writable by the owner
sudo: fatal error, unable to load plug
Enter the following command
su root
chmod 644 usr/libexec/sudo/sudoers.so
chown -R root /usr/libexec/sudo