Disable SCTP Support

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Description

The Stream Control Transmission Protocol (SCTP) is a transport layer protocol, designed to support the idea of message-oriented communication, with several streams of messages within one connection. To configure the system to prevent the sctp kernel module from being loaded, add the following line to the file /etc/modprobe.d/sctp.conf:

install sctp /bin/false

This entry will cause a non-zero return value during a sctp module installation and additionally convey the meaning of the entry to the user in form of an error message. If you would like to omit a non-zero return value and an error message, you may want to add a different line instead (both /bin/true and /bin/false are allowed by OVAL and will be accepted by the scan):

install sctp /bin/true

Rationale

Disabling SCTP protects the system against exploitation of any flaws in its implementation.

Remediation

Shell script

The following script can be run on the host to remediate the issue.

#!/bin/bash

# Remediation is applicable only in certain platforms
if rpm --quiet -q kernel-core; then

if LC_ALL=C grep -q -m 1 "^install sctp" /etc/modprobe.d/sctp.conf ; then
	
	sed -i 's#^install sctp.*#install sctp /bin/false#g' /etc/modprobe.d/sctp.conf
else
	echo -e "\n# Disable per security requirements" >> /etc/modprobe.d/sctp.conf
	echo "install sctp /bin/false" >> /etc/modprobe.d/sctp.conf
fi

if ! LC_ALL=C grep -q -m 1 "^blacklist sctp$" /etc/modprobe.d/sctp.conf ; then
	echo "blacklist sctp" >> /etc/modprobe.d/sctp.conf
fi

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

Ansible playbook

The following playbook can be run with Ansible to remediate the issue.

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - CCE-90489-6
  - CJIS-5.10.1
  - NIST-800-171-3.4.6
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - PCI-DSS-Req-1.4.2
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.2
  - disable_strategy
  - kernel_module_sctp_disabled
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required

- name: Ensure kernel module 'sctp' is disabled
  ansible.builtin.lineinfile:
    create: true
    dest: /etc/modprobe.d/sctp.conf
    regexp: install\s+sctp
    line: install sctp /bin/false
  when: '"kernel-core" in ansible_facts.packages'
  tags:
  - CCE-90489-6
  - CJIS-5.10.1
  - NIST-800-171-3.4.6
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - PCI-DSS-Req-1.4.2
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.2
  - disable_strategy
  - kernel_module_sctp_disabled
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required

- name: Ensure kernel module 'sctp' is blacklisted
  ansible.builtin.lineinfile:
    create: true
    dest: /etc/modprobe.d/sctp.conf
    regexp: ^blacklist sctp$
    line: blacklist sctp
  when: '"kernel-core" in ansible_facts.packages'
  tags:
  - CCE-90489-6
  - CJIS-5.10.1
  - NIST-800-171-3.4.6
  - NIST-800-53-CM-6(a)
  - NIST-800-53-CM-7(a)
  - NIST-800-53-CM-7(b)
  - PCI-DSS-Req-1.4.2
  - PCI-DSSv4-1.4
  - PCI-DSSv4-1.4.2
  - disable_strategy
  - kernel_module_sctp_disabled
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required