Disable storing core dumps

An XCCDF Rule

Description

To set the runtime status of the kernel.core_pattern kernel parameter, run the following command:

$ sudo sysctl -w kernel.core_pattern=|/bin/false

To make sure that the setting is persistent, add the following line to a file in the directory /etc/sysctl.d:

kernel.core_pattern = |/bin/false

Rationale

A core dump includes a memory image taken at the time the operating system terminates an application. The memory image could contain sensitive data and is generally useful only for developers trying to debug problems.

ID: xccdf_org.ssgproject.content_rule_sysctl_kernel_core_pattern
Severity: Medium
References: CCI-000366

SC-7(10)

SRG-OS-000480-GPOS-00227

3.3 3.3.1 3.3.1.1
Updated: 5 days ago

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

# Comment out any occurrences of kernel.core_pattern from /etc/sysctl.d/*.conf files

for f in /etc/sysctl.d/*.conf /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf; do

  # skip systemd-sysctl symlink (/etc/sysctl.d/99-sysctl.conf -> /etc/sysctl.conf)
  if [[ "$(readlink -f "$f")" == "/etc/sysctl.conf" ]]; then continue; fi

  matching_list=$(grep -P '^(?!#).*[\s]*kernel.core_pattern.*$' $f | uniq )
  if ! test -z "$matching_list"; then
    while IFS= read -r entry; do
      escaped_entry=$(sed -e 's|/|\\/|g' <<< "$entry")
      # comment out "kernel.core_pattern" matches to preserve user data
      sed -i --follow-symlinks "s/^${escaped_entry}$/# &/g" $f
    done <<< "$matching_list"
  fi
done

#
# Set sysctl config file which to save the desired value
#

SYSCONFIG_FILE="/etc/sysctl.conf"


#
# Set runtime for kernel.core_pattern
#
/sbin/sysctl -q -n -w kernel.core_pattern="|/bin/false"

#
# If kernel.core_pattern present in /etc/sysctl.conf, change value to "|/bin/false"
#	else, add "kernel.core_pattern = |/bin/false" to /etc/sysctl.conf
#

# Strip any search characters in the key arg so that the key can be replaced without
# adding any search characters to the config file.
stripped_key=$(sed 's/[\^=\$,;+]*//g' <<< "^kernel.core_pattern")

# shellcheck disable=SC2059
printf -v formatted_output "%s = %s" "$stripped_key" "|/bin/false"

# If the key exists, change it. Otherwise, add it to the config_file.
# We search for the key string followed by a word boundary (matched by \>),
# so if we search for 'setting', 'setting2' won't match.
if LC_ALL=C grep -q -m 1 -i -e "^kernel.core_pattern\\>" "${SYSCONFIG_FILE}"; then
    escaped_formatted_output=$(sed -e 's|/|\\/|g' <<< "$formatted_output")
    LC_ALL=C sed -i --follow-symlinks "s/^kernel.core_pattern\\>.*/$escaped_formatted_output/gi" "${SYSCONFIG_FILE}"
else
    if [[ -s "${SYSCONFIG_FILE}" ]] && [[ -n "$(tail -c 1 -- "${SYSCONFIG_FILE}" || true)" ]]; then
        LC_ALL=C sed -i --follow-symlinks '$a'\\ "${SYSCONFIG_FILE}"
    fi
    printf '%s\n' "$formatted_output" >> "${SYSCONFIG_FILE}"
fi

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

---
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:      version: 3.1.0
    storage:
      files:
      - contents:
          source: data:,kernel.core_pattern%20%3D%20%7C/bin/false%0A
        mode: 0644
        path: /etc/sysctl.d/75-sysctl_kernel_core_pattern.conf
        overwrite: true

- name: Gather the package facts
  package_facts:
    manager: auto
  tags:
  - NIST-800-53-SC-7(10)
  - PCI-DSSv4-3.3  - PCI-DSSv4-3.3.1
  - PCI-DSSv4-3.3.1.1
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_kernel_core_pattern

- name: List /etc/sysctl.d/*.conf files
  find:
    paths:
    - /etc/sysctl.d/
    - /run/sysctl.d/
    - /usr/local/lib/sysctl.d/
    - /usr/lib/sysctl.d/
    contains: ^[\s]*kernel.core_pattern.*$
    patterns: '*.conf'
    file_type: any
  register: find_sysctl_d
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-53-SC-7(10)
  - PCI-DSSv4-3.3
  - PCI-DSSv4-3.3.1
  - PCI-DSSv4-3.3.1.1
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_kernel_core_pattern

- name: Comment out any occurrences of kernel.core_pattern from config files
  replace:
    path: '{{ item.path }}'
    regexp: ^[\s]*kernel.core_pattern
    replace: '#kernel.core_pattern'
  loop: '{{ find_sysctl_d.files }}'
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-53-SC-7(10)
  - PCI-DSSv4-3.3
  - PCI-DSSv4-3.3.1
  - PCI-DSSv4-3.3.1.1
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_kernel_core_pattern

- name: Ensure sysctl kernel.core_pattern is set to |/bin/false
  sysctl:
    name: kernel.core_pattern
    value: '|/bin/false'
    sysctl_file: /etc/sysctl.conf
    state: present
    reload: true
  when: '"kernel" in ansible_facts.packages'
  tags:
  - NIST-800-53-SC-7(10)
  - PCI-DSSv4-3.3
  - PCI-DSSv4-3.3.1
  - PCI-DSSv4-3.3.1.1
  - disable_strategy
  - low_complexity
  - medium_disruption
  - medium_severity
  - reboot_required
  - sysctl_kernel_core_pattern

Disable storing core dumps

Description

Rationale

Remediation - Shell Script

Remediation - Kubernetes Patch

Remediation - Ansible