openstack-ansible-security/doc/source/developer-notes/V-38497.rst

Ubuntu 14.04 allows accounts with null passwords to authenticate via PAM by default. This STIG requires that those login attempts are blocked.

In Ubuntu, this functionality is controlled by the nullok_secure parameter found in /etc/pam.d/common-auth. The Ansible task for this STIG will remove the nullok_secure from the PAM configuration file. The effects of the change are immediate and no service restarts are required.

However, deployers can opt-out of this change by adjusting an Ansible variable:

pam_remove_nullok: no

Setting the variable to yes (the default) will cause the Ansible tasks to remove the nullok_secure parameter while setting the variable to no will leave the PAM configuration unchanged.