Disable Full User Name on Splash Shield

An XCCDF Rule

Description

By default when the screen is locked, the splash shield will show the user's full name. This should be disabled to prevent casual observers from seeing who has access to the system. This can be disabled by adding or setting show-full-name-in-top-bar to false in /etc/dconf/db/local.d/00-security-settings. For example:

[org/gnome/desktop/screensaver]
show-full-name-in-top-bar=false

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/screensaver/show-full-name-in-top-bar

After the settings have been set, run dconf update.

Rationale

Setting the splash screen to not reveal the logged in user's name conceals who has access to the system from passersby.

ID: xccdf_org.ssgproject.content_rule_dconf_gnome_screensaver_user_info
Severity: Medium
References: FMT_MOF_EXT.1
Updated: about 1 year ago

# 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/screensaver\\]" "/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 [ "${#SETTINGSFILES[@]}" -ne 0 ]
then
    if grep -q "^\\s*show-full-name-in-top-bar\\s*=" "${SETTINGSFILES[@]}"
    then
        
        sed -Ei "s/(^\s*)show-full-name-in-top-bar(\s*=)/#\1show-full-name-in-top-bar\2/g" "${SETTINGSFILES[@]}"
    fi
fi

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

escaped_value="$(sed -e 's/\\/\\\\/g' <<< "false")"
if grep -q "^\\s*show-full-name-in-top-bar\\s*=" "${DCONFFILE}"
then
        sed -i "s/\\s*show-full-name-in-top-bar\\s*=\\s*.*/show-full-name-in-top-bar=${escaped_value}/g" "${DCONFFILE}"
    else
        sed -i "\\|\\[org/gnome/desktop/screensaver\\]|a\\show-full-name-in-top-bar=${escaped_value}" "${DCONFFILE}"
fi

dconf update
# Check for setting in any of the DConf db directories
LOCKFILES=$(grep -r "^/org/gnome/desktop/screensaver/show-full-name-in-top-bar$" "/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 "${LOCKFILES}" ]]
then
    sed -i -E "s|^/org/gnome/desktop/screensaver/show-full-name-in-top-bar$|#&|" "${LOCKFILES[@]}"
fi

if ! grep -qr "^/org/gnome/desktop/screensaver/show-full-name-in-top-bar$" /etc/dconf/db/local.d/
then
    echo "/org/gnome/desktop/screensaver/show-full-name-in-top-bar" >> "/etc/dconf/db/local.d/locks/00-security-settings-lock"
fi

dconf update

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

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - dconf_gnome_screensaver_user_info
  - low_complexity  - medium_disruption
  - medium_severity
  - no_reboot_needed
  - unknown_strategy

- name: Disable Full Username on Splash Screen
  ini_file:
    dest: /etc/dconf/db/local.d/00-security-settings
    section: org/gnome/desktop/screensaver
    option: show-full-name-in-top-bar
    value: 'false'
    create: true
    no_extra_spaces: true
  when:
  - '"gdm" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - dconf_gnome_screensaver_user_info
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed
  - unknown_strategy

- name: Prevent user modification of GNOME show-full-name-in-top-bar
  lineinfile:
    path: /etc/dconf/db/local.d/locks/00-security-settings-lock
    regexp: ^/org/gnome/desktop/screensaver/show-full-name-in-top-bar$
    line: /org/gnome/desktop/screensaver/show-full-name-in-top-bar
    create: true
  when:
  - '"gdm" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - dconf_gnome_screensaver_user_info
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed
  - unknown_strategy

- name: Dconf Update
  command: dconf update
  when:
  - '"gdm" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - dconf_gnome_screensaver_user_info
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed
  - unknown_strategy

Disable Full User Name on Splash Shield

Description

Rationale

Remediation - Shell Script

Remediation - Ansible