Generate USBGuard Policy

An XCCDF Rule

Description

By default USBGuard when enabled prevents access to all USB devices and this lead to inaccessible system if they use USB mouse/keyboard. To prevent this scenario, the initial policy configuration must be generated based on current connected USB devices.

Rationale

The usbguard must be configured to allow connected USB devices to work properly, avoiding the system to become inaccessible.

ID: xccdf_org.ssgproject.content_rule_usbguard_generate_policy
Severity: Medium
References: CCI-000416 CCI-001958

CM-8(3)(a) IA-3

FMT_SMF_EXT.1

SRG-OS-000378-GPOS-00163

OL08-00-040140

SV-248863r853872_rule
Updated: about 1 year ago

# Remediation is applicable only in certain platforms
if ( [ ! -f /.dockerenv ] && [ ! -f /run/.containerenv ] && ! grep -q s390x /proc/sys/kernel/osrelease ); then

if rpm --quiet -q usbguard
then
    USBGUARD_CONF=/etc/usbguard/rules.conf    if [ ! -f "$USBGUARD_CONF" ] || [ ! -s "$USBGUARD_CONF" ]; then
        usbguard generate-policy > $USBGUARD_CONF
        if [ ! -s "$USBGUARD_CONF" ]; then
            # make sure OVAL check doesn't fail on systems where
            # generate-policy doesn't find any USB devices (for
            # example a system might not have a USB bus)
            echo "# No USB devices found" > $USBGUARD_CONF
        fi
        # make sure it has correct permissions
        chmod 600 $USBGUARD_CONF

        SYSTEMCTL_EXEC='/usr/bin/systemctl'
        "$SYSTEMCTL_EXEC" unmask 'usbguard.service'
        "$SYSTEMCTL_EXEC" restart 'usbguard.service'
        "$SYSTEMCTL_EXEC" enable 'usbguard.service'
    fi
else
    echo "USBGuard is not installed. No remediation was applied!"
fi

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

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - DISA-STIG-OL08-00-040140
  - NIST-800-53-CM-8(3)(a)  - NIST-800-53-IA-3
  - configure_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - usbguard_generate_policy

- name: Generate USBGuard Policy
  block:

  - name: Gather the package facts
    package_facts:
      manager: auto

  - name: Check that the /etc/usbguard/rules.conf exists
    stat:
      path: /etc/usbguard/rules.conf
    register: policy_file

  - name: Create USBGuard Policy configuration
    command: usbguard generate-policy
    register: policy
    when: not policy_file.stat.exists or policy_file.stat.size == 0

  - name: Copy the Generated Policy configuration to a persistent file
    copy:
      content: '{{ policy.stdout }}'
      dest: /etc/usbguard/rules.conf
      mode: 384
    when: not policy_file.stat.exists or policy_file.stat.size == 0

  - name: Add comment into /etc/usbguard/rules.conf when system has no USB devices
    lineinfile:
      path: /etc/usbguard/rules.conf
      line: '# No USB devices found'
      state: present
    when: not policy_file.stat.exists or policy_file.stat.size == 0

  - name: Enable service usbguard
    systemd:
      name: usbguard
      enabled: 'yes'
      state: started
      masked: 'no'
  when:
  - ( ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
    and ansible_architecture != "s390x" )
  - '"usbguard" in ansible_facts.packages'
  tags:
  - DISA-STIG-OL08-00-040140
  - NIST-800-53-CM-8(3)(a)
  - NIST-800-53-IA-3
  - configure_strategy
  - low_complexity
  - low_disruption
  - medium_severity
  - no_reboot_needed
  - usbguard_generate_policy

Generate USBGuard Policy

Description

Rationale

Remediation - Shell Script

Remediation - Ansible