Disable IPv6 Networking Support Automatic Loading

An XCCDF Rule

Description

To prevent the IPv6 kernel module (ipv6) from binding to the IPv6 networking stack, add the following line to /etc/modprobe.d/disabled.conf (or another file in /etc/modprobe.d):

options ipv6 disable=1

This permits the IPv6 module to be loaded (and thus satisfy other modules that depend on it), while disabling support for the IPv6 protocol.

Rationale

Any unnecessary network stacks - including IPv6 - should be disabled, to reduce the vulnerability to exploitation.

ID: xccdf_org.ssgproject.content_rule_kernel_module_ipv6_option_disabled
Severity: Medium
References: 11 14 3 9

BAI10.01 BAI10.02 BAI10.03 BAI10.05 DSS05.02 DSS05.05 DSS06.06

4.3.3.5.1 4.3.3.5.2 4.3.3.5.3 4.3.3.5.4 4.3.3.5.5 4.3.3.5.6 4.3.3.5.7 4.3.3.5.8 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 4.3.3.7.1 4.3.3.7.2 4.3.3.7.3 4.3.3.7.4 4.3.4.3.2 4.3.4.3.3

SR 1.1 SR 1.10 SR 1.11 SR 1.12 SR 1.13 SR 1.2 SR 1.3 SR 1.4 SR 1.5 SR 1.6 SR 1.7 SR 1.8 SR 1.9 SR 2.1 SR 2.2 SR 2.3 SR 2.4 SR 2.5 SR 2.6 SR 2.7 SR 7.6

A.12.1.2 A.12.5.1 A.12.6.2 A.14.2.2 A.14.2.3 A.14.2.4 A.9.1.2

CM-6(a) CM-7(a) CM-7(b)

PR.IP-1 PR.PT-3
Updated: over 1 year ago

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)  - NIST-800-53-CM-7(b)
  - disable_strategy
  - kernel_module_ipv6_option_disabled
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required

- name: Disable IPv6 Networking kernel module
  lineinfile:
    create: true
    dest: /etc/modprobe.d/ipv6.conf
    regexp: ^options\s+ipv6\s+disable=\d
    line: options ipv6 disable=1
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - disable_strategy
  - kernel_module_ipv6_option_disabled
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required

- name: Ensure disable_ipv6 (all and default) is set to 1
  sysctl:
    name: '{{ item }}'
    value: '1'
    state: present
    reload: true
  with_items:
  - net.ipv6.conf.all.disable_ipv6
  - net.ipv6.conf.default.disable_ipv6
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - disable_strategy
  - kernel_module_ipv6_option_disabled
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required

# Remediation is applicable only in certain platforms
if dpkg-query --show --showformat='${db:Status-Status}
' 'kernel' 2>/dev/null | grep -q installed; then

# Prevent the IPv6 kernel module (ipv6) from loading the IPv6 networking stack
echo "options ipv6 disable=1" > /etc/modprobe.d/ipv6.conf
# Since according to: https://access.redhat.com/solutions/72733
# "ipv6 disable=1" options doesn't always disable the IPv6 networking stack from
# loading, instruct also sysctl configuration to disable IPv6 according to:
# https://access.redhat.com/solutions/8709#rhel6disable

declare -a IPV6_SETTINGS=("net.ipv6.conf.all.disable_ipv6" "net.ipv6.conf.default.disable_ipv6")

for setting in "${IPV6_SETTINGS[@]}"
do
	# Set runtime =1 for setting
	/sbin/sysctl -q -n -w "$setting=1"

	# If setting is present in /etc/sysctl.conf, change value to "1"
	# else, add "$setting = 1" to /etc/sysctl.conf
	if grep -q ^"$setting" /etc/sysctl.conf ; then
		sed -i "s/^$setting.*/$setting = 1/g" /etc/sysctl.conf
	else
		echo "" >> /etc/sysctl.conf
		echo "# Set $setting = 1 per security requirements" >> /etc/sysctl.conf
		echo "$setting = 1" >> /etc/sysctl.conf
	fi
done

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

Disable IPv6 Networking Support Automatic Loading

Description

Rationale

Remediation - Ansible

Remediation - Shell Script