CIS Controls 5.3.* (PAM)

[ucguerrilla]

On Ubuntu 16.04 LTS, I encountered several issues with the PAM configurations that may warrant review / confirmation. Tested this on a basic server configuration with base system OpenSSH installed (only).

Under the CIS controls for 5.3:

1. Since we are using pam-pwquality, you may want to install the linux package: apt-get install libpam-pwquality BEFORE copying files.

2. The template file (templates/common-passwd-CIS) copy command had no affect in my testing because the system file that you want to overwrite is actually: /etc/pam.d/common-password

3. The templates/command-passwd-CIS syntax is actually non-compliant with CIS control 5.3.3, which is expecting the module pam_pwhistory to be used. Also, the section added to the template following the "#CIS" comment did not behave as expected in my testing. I think a template config like the following may work better: (at least, it achieved my objectives and behaved as expected/desired for password resets for local users and from root)

#
# /etc/pam.d/common-password - password-related modules common to all services
#
# This file is included from other service-specific PAM config files,
# and should contain a list of modules that define the services to be
# used to change user passwords.  The default is pam_unix.

# Explanation of pam_unix options:
#
# The "sha512" option enables salted SHA512 passwords.  Without this option,
# the default is Unix crypt.  Prior releases used the option "md5".
#
# The "obscure" option replaces the old `OBSCURE_CHECKS_ENAB' option in
# login.defs.
#
# See the pam_unix manpage for other options.

# As of pam 1.0.1-6, this file is managed by pam-auth-update by default.
# To take advantage of this, it is recommended that you configure any
# local modules either before or after the default block, and use
# pam-auth-update to manage selection of other modules.  See
# pam-auth-update(8) for details.

# here are the per-package modules (the "Primary" block)
password    requisite           pam_pwquality.so  try_first_pass retry=3
password    required            pam_pwhistory.so  use_authtok  remember=5
password    [success=1 default=ignore]  pam_unix.so obscure use_authtok try_first_pass sha512 remember=5
# here's the fallback if no module succeeds
password    requisite           pam_deny.so
# prime the stack with a positive return value if there isn't one already;
# this avoids us returning an error just because nothing sets a success code
# since the modules above will each just jump around
password    required            pam_permit.so

# and here are more per-package modules (the "Additional" block)
# end of pam-auth-update config

[Jsitech]

Thanks for bringing this to my attention, will look into it.