Disable User Administration in GNOME3

An XCCDF Rule

Description

By default, GNOME will allow all users to have some administratrion capability. This should be disabled so that non-administrative users are not making configuration changes. To configure the system to disable user administration capability in the Graphical User Interface (GUI), add or set user-administration-disabled to true in /etc/dconf/db/local.d/00-security-settings. For example:

[org/gnome/desktop/lockdown]
user-administration-disabled=true

Once the settings have been added, add a lock to /etc/dconf/db/local.d/locks/00-security-settings-lock to prevent user modification. For example:

/org/gnome/desktop/lockdown/user-administration-disabled

After the settings have been set, run dconf update.

Rationale

Allowing all users to have some administratrive capabilities to the system through the Graphical User Interface (GUI) when they would not have them otherwise could allow unintended configuration changes as well as a nefarious user the capability to make system changes such as adding new accounts, etc.

ID: xccdf_org.ssgproject.content_rule_dconf_gnome_disable_user_admin
Severity: High
References: 3.1.5

FMT_MOD_EXT.1
Updated: about 1 year ago

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-171-3.1.5
  - dconf_gnome_disable_user_admin  - high_severity
  - low_complexity
  - medium_disruption
  - no_reboot_needed
  - unknown_strategy

- name: Detect if user-administration-disabled can be found on /etc/dconf/db/local.d/
  find:
    path: /etc/dconf/db/local.d/
    contains: ^\s*user-administration-disabled
  register: dconf_gnome_disable_user_admin_config_files
  when:
  - '"gdm" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - NIST-800-171-3.1.5
  - dconf_gnome_disable_user_admin
  - high_severity
  - low_complexity
  - medium_disruption
  - no_reboot_needed
  - unknown_strategy

- name: Configure user-administration-disabled - default file
  ini_file:
    dest: /etc/dconf/db/local.d//00-security-settings
    section: org/gnome/desktop/lockdown
    option: user-administration-disabled
    value: 'true'
    create: true
  when:
  - '"gdm" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  - dconf_gnome_disable_user_admin_config_files is defined and dconf_gnome_disable_user_admin_config_files.matched
    == 0
  tags:
  - NIST-800-171-3.1.5
  - dconf_gnome_disable_user_admin
  - high_severity
  - low_complexity
  - medium_disruption
  - no_reboot_needed
  - unknown_strategy

- name: Configure user-administration-disabled - existing files
  ini_file:
    dest: '{{ item.path }}'
    section: org/gnome/desktop/lockdown
    option: user-administration-disabled
    value: 'true'
    create: true
  with_items: '{{ dconf_gnome_disable_user_admin_config_files.files }}'
  when:
  - '"gdm" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  - dconf_gnome_disable_user_admin_config_files is defined and dconf_gnome_disable_user_admin_config_files.matched
    > 0
  tags:
  - NIST-800-171-3.1.5
  - dconf_gnome_disable_user_admin
  - high_severity
  - low_complexity
  - medium_disruption
  - no_reboot_needed
  - unknown_strategy

- name: Detect if lock for user-administration-disabled can be found on /etc/dconf/db/local.d/
  find:
    path: /etc/dconf/db/local.d/locks
    contains: ^\s*user-administration-disabled
  register: dconf_gnome_disable_user_admin_lock_files
  when:
  - '"gdm" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - NIST-800-171-3.1.5
  - dconf_gnome_disable_user_admin
  - high_severity
  - low_complexity
  - medium_disruption
  - no_reboot_needed
  - unknown_strategy

- name: Prevent user modification user-administration-disabled - default file
  lineinfile:
    path: /etc/dconf/db/local.d/locks/00-security-settings-lock
    regexp: ^/org/gnome/desktop/lockdown/user-administration-disabled$
    line: /org/gnome/desktop/lockdown/user-administration-disabled
    create: true
  when:
  - '"gdm" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  - dconf_gnome_disable_user_admin_lock_files is defined and dconf_gnome_disable_user_admin_lock_files.matched
    == 0
  tags:
  - NIST-800-171-3.1.5
  - dconf_gnome_disable_user_admin
  - high_severity
  - low_complexity
  - medium_disruption
  - no_reboot_needed
  - unknown_strategy

- name: Prevent user modification user-administration-disabled - existing files
  lineinfile:
    path: '{{ item.path }}'
    regexp: ^/org/gnome/desktop/lockdown/user-administration-disabled$
    line: /org/gnome/desktop/lockdown/user-administration-disabled
    create: true
  with_items: '{{ dconf_gnome_disable_user_admin_lock_files.files }}'
  when:
  - '"gdm" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  - dconf_gnome_disable_user_admin_lock_files is defined and dconf_gnome_disable_user_admin_lock_files.matched
    > 0
  tags:
  - NIST-800-171-3.1.5
  - dconf_gnome_disable_user_admin
  - high_severity
  - low_complexity
  - medium_disruption
  - no_reboot_needed
  - unknown_strategy

- name: Dconf Update - user-administration-disabled
  command: dconf update
  when:
  - '"gdm" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - NIST-800-171-3.1.5
  - dconf_gnome_disable_user_admin
  - high_severity
  - low_complexity
  - medium_disruption
  - no_reboot_needed
  - unknown_strategy

# Remediation is applicable only in certain platforms
if rpm --quiet -q gdm && { [ ! -f /.dockerenv ] && [ ! -f /run/.containerenv ]; }; then

# Check for setting in any of the DConf db directories
# If files contain ibus or distro, ignore them.
# The assignment assumes that individual filenames don't contain :readarray -t SETTINGSFILES < <(grep -r "\\[org/gnome/desktop/lockdown\\]" "/etc/dconf/db/" \
                                | grep -v 'distro\|ibus\|local.d' | cut -d":" -f1)
DCONFFILE="/etc/dconf/db/local.d/00-security-settings"
DBDIR="/etc/dconf/db/local.d"

mkdir -p "${DBDIR}"

# Comment out the configurations in databases different from the target one
if [ "${#SETTINGSFILES[@]}" -ne 0 ]
then
    if grep -q "^\\s*user-administration-disabled\\s*=" "${SETTINGSFILES[@]}"
    then
        
        sed -Ei "s/(^\s*)user-administration-disabled(\s*=)/#\1user-administration-disabled\2/g" "${SETTINGSFILES[@]}"
    fi
fi

[ ! -z "${DCONFFILE}" ] && echo "" >> "${DCONFFILE}"
if ! grep -q "\\[org/gnome/desktop/lockdown\\]" "${DCONFFILE}"
then
    printf '%s\n' "[org/gnome/desktop/lockdown]" >> ${DCONFFILE}
fi

escaped_value="$(sed -e 's/\\/\\\\/g' <<< "true")"
if grep -q "^\\s*user-administration-disabled\\s*=" "${DCONFFILE}"
then
        sed -i "s/\\s*user-administration-disabled\\s*=\\s*.*/user-administration-disabled=${escaped_value}/g" "${DCONFFILE}"
    else
        sed -i "\\|\\[org/gnome/desktop/lockdown\\]|a\\user-administration-disabled=${escaped_value}" "${DCONFFILE}"
fi

dconf update
# Check for setting in any of the DConf db directories
LOCKFILES=$(grep -r "^/org/gnome/desktop/lockdown/user-administration-disabled$" "/etc/dconf/db/" \
            | grep -v 'distro\|ibus\|local.d' | grep ":" | cut -d":" -f1)
LOCKSFOLDER="/etc/dconf/db/local.d/locks"

mkdir -p "${LOCKSFOLDER}"

# Comment out the configurations in databases different from the target one
if [[ ! -z "${LOCKFILES}" ]]
then
    sed -i -E "s|^/org/gnome/desktop/lockdown/user-administration-disabled$|#&|" "${LOCKFILES[@]}"
fi

if ! grep -qr "^/org/gnome/desktop/lockdown/user-administration-disabled$" /etc/dconf/db/local.d/
then
    echo "/org/gnome/desktop/lockdown/user-administration-disabled" >> "/etc/dconf/db/local.d/locks/00-security-settings-lock"
fi

dconf update

else
    >&2 echo 'Remediation is not applicable, nothing was done'
fi

Disable User Administration in GNOME3

Description

Rationale

Remediation - Ansible

Remediation - Shell Script