RHEL 8 must prevent the loading of a new kernel for later execution.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-230266	RHEL-08-010372	SV-230266r627750_rule		Medium

Description
Changes to any software components can have significant effects on the overall security of the operating system. This requirement ensures the software has not been tampered with and that it has been provided by a trusted vendor. Disabling kexec_load prevents an unsigned kernel image (that could be a windows kernel or modified vulnerable kernel) from being loaded. Kexec can be used subvert the entire secureboot process and should be avoided at all costs especially since it can load unsigned kernel images.

Description

Changes to any software components can have significant effects on the overall security of the operating system. This requirement ensures the software has not been tampered with and that it has been provided by a trusted vendor. Disabling kexec_load prevents an unsigned kernel image (that could be a windows kernel or modified vulnerable kernel) from being loaded. Kexec can be used subvert the entire secureboot process and should be avoided at all costs especially since it can load unsigned kernel images.

STIG	Date
Red Hat Enterprise Linux 8 Security Technical Implementation Guide	2021-03-04

Details

Check Text ( C-32935r567544_chk )
Verify the operating system is configured to disable kernel image loading with the following commands: Check the status of the kernel.kexec_load_disabled kernel parameter $ sudo sysctl kernel.kexec_load_disabled kernel.kexec_load_disabled = 1 If "kernel.kexec_load_disabled" is not set to "1" or is missing, this is a finding. Check that the configuration files are present to enable this kernel parameter $ sudo grep -r kernel.kexec_load_disabled /etc/sysctl.conf /etc/sysctl.d/*.conf /etc/sysctl.d/99-sysctl.conf:kernel.kexec_load_disabled = 1 If "kernel.kexec_load_disabled" is not set to "1", is missing or commented out, this is a finding.

Check Text ( C-32935r567544_chk )

Verify the operating system is configured to disable kernel image loading with the following commands:

Check the status of the kernel.kexec_load_disabled kernel parameter

$ sudo sysctl kernel.kexec_load_disabled

kernel.kexec_load_disabled = 1

If "kernel.kexec_load_disabled" is not set to "1" or is missing, this is a finding.

Check that the configuration files are present to enable this kernel parameter

$ sudo grep -r kernel.kexec_load_disabled /etc/sysctl.conf /etc/sysctl.d/*.conf

/etc/sysctl.d/99-sysctl.conf:kernel.kexec_load_disabled = 1

If "kernel.kexec_load_disabled" is not set to "1", is missing or commented out, this is a finding.

Fix Text (F-32910r567545_fix)
Configure the operating system to disable kernel image loading. Add or edit the following line in a system configuration file in the "/etc/sysctl.d/" directory: kernel.kexec_load_disabled = 1 Load settings from all system configuration files with the following command: $ sudo sysctl --system