Verify /boot/grub2/user.cfg Group Ownership
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Description
The file /boot/grub2/user.cfg
should be group-owned by the root
group to prevent reading or modification of the file.
To properly set the group owner of /boot/grub2/user.cfg
, run the command:
$ sudo chgrp root /boot/grub2/user.cfg
Rationale
The root
group is a highly-privileged group. Furthermore, the group-owner of this
file should not have any access privileges anyway. Non-root users who read the boot parameters
may be able to identify weaknesses in security upon boot and be able to exploit them.
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 [ ! -d /sys/firmware/efi ] && rpm --quiet -q grub2-common && { [ ! -f /.dockerenv ] && [ ! -f /run/.containerenv ]; }; then
chgrp 0 /boot/grub2/user.cfg
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-86008-0
- CJIS-5.5.2.2
- NIST-800-171-3.4.5
- NIST-800-53-AC-6(1)
- NIST-800-53-CM-6(a)
- PCI-DSS-Req-7.1
- PCI-DSSv4-2.2.6
- configure_strategy
- file_groupowner_user_cfg
- low_complexity
- low_disruption
- medium_severity
- no_reboot_needed
- name: Test for existence /boot/grub2/user.cfg
stat:
path: /boot/grub2/user.cfg
register: file_exists
when:
- '"/boot/efi" not in ansible_mounts | map(attribute="mount") | list'
- '"grub2-common" in ansible_facts.packages'
- ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
tags:
- CCE-86008-0
- CJIS-5.5.2.2
- NIST-800-171-3.4.5
- NIST-800-53-AC-6(1)
- NIST-800-53-CM-6(a)
- PCI-DSS-Req-7.1
- PCI-DSSv4-2.2.6
- configure_strategy
- file_groupowner_user_cfg
- low_complexity
- low_disruption
- medium_severity
- no_reboot_needed
- name: Ensure group owner 0 on /boot/grub2/user.cfg
file:
path: /boot/grub2/user.cfg
group: '0'
when:
- '"/boot/efi" not in ansible_mounts | map(attribute="mount") | list'
- '"grub2-common" in ansible_facts.packages'
- ansible_virtualization_type not in ["docker", "lxc", "openvz", "podman", "container"]
- file_exists.stat is defined and file_exists.stat.exists
tags:
- CCE-86008-0
- CJIS-5.5.2.2
- NIST-800-171-3.4.5
- NIST-800-53-AC-6(1)
- NIST-800-53-CM-6(a)
- PCI-DSS-Req-7.1
- PCI-DSSv4-2.2.6
- configure_strategy
- file_groupowner_user_cfg
- low_complexity
- low_disruption
- medium_severity
- no_reboot_needed