Ensure Users Cannot Change GNOME3 Screensaver Settings

An XCCDF Rule

Description

If not already configured, ensure that users cannot change GNOME3 screensaver lock settings by adding /org/gnome/desktop/screensaver/lock-delay to /etc/dconf/db/local.d/locks/00-security-settings-lock to prevent user modification. For example:

/org/gnome/desktop/screensaver/lock-delay

After the settings have been set, run dconf update.

Rationale

A session time-out lock is a temporary action taken when a user stops work and moves away from the immediate physical vicinity of the information system but does not logout because of the temporary nature of the absence. Rather than relying on the user to manually lock their operating system session prior to vacating the vicinity, GNOME desktops can be configured to identify when a user's session has idled and take action to initiate the session lock. As such, users should not be allowed to change session settings.

ID: xccdf_org.ssgproject.content_rule_dconf_gnome_screensaver_user_locks
Severity: Medium
References: 1 12 15 16

DSS05.04 DSS05.10 DSS06.10

3.1.10

CCI-000057 CCI-000060

4.3.3.6.1 4.3.3.6.2 4.3.3.6.3 4.3.3.6.4 4.3.3.6.5 4.3.3.6.6 4.3.3.6.7 4.3.3.6.8 4.3.3.6.9

SR 1.1 SR 1.10 SR 1.2 SR 1.5 SR 1.7 SR 1.8 SR 1.9

A.18.1.4 A.9.2.1 A.9.2.4 A.9.3.1 A.9.4.2 A.9.4.3

CM-6(a)

PR.AC-7

FMT_MOF_EXT.1

SRG-OS-000029-GPOS-00010 SRG-OS-000031-GPOS-00012

SV-204399r880773_rule

1.7.5
Updated: about 1 year ago

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - DISA-STIG-RHEL-07-010081
  - NIST-800-171-3.1.10  - NIST-800-53-CM-6(a)
  - dconf_gnome_screensaver_user_locks
  - low_complexity
  - medium_disruption
  - medium_severity
  - no_reboot_needed
  - unknown_strategy

- name: Prevent user modification of GNOME lock-delay
  lineinfile:
    path: /etc/dconf/db/local.d/locks/00-security-settings-lock
    regexp: ^/org/gnome/desktop/screensaver/lock-delay$
    line: /org/gnome/desktop/screensaver/lock-delay
    create: true
  when:
  - '"gdm" in ansible_facts.packages'
  - ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
  tags:
  - DISA-STIG-RHEL-07-010081
  - NIST-800-171-3.1.10
  - NIST-800-53-CM-6(a)
  - dconf_gnome_screensaver_user_locks
  - 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:
  - DISA-STIG-RHEL-07-010081
  - NIST-800-171-3.1.10
  - NIST-800-53-CM-6(a)
  - dconf_gnome_screensaver_user_locks
  - low_complexity
  - medium_disruption
  - medium_severity
  - 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
LOCKFILES=$(grep -r "^/org/gnome/desktop/screensaver/lock-delay$" "/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 "${LOCKFILES}" ]]
then
    sed -i -E "s|^/org/gnome/desktop/screensaver/lock-delay$|#&|" "${LOCKFILES[@]}"
fi

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

dconf update

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

Ensure Users Cannot Change GNOME3 Screensaver Settings

Description

Rationale

Remediation - Ansible

Remediation - Shell Script