The system must limit the ability of processes to have simultaneous write and execute access to memory.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-217910	RHEL-06-000079	SV-217910r505923_rule		Medium

Description
ExecShield uses the segmentation feature on all x86 systems to prevent execution in memory higher than a certain address. It writes an address as a limit in the code segment descriptor, to control where code can be executed, on a per-process basis. When the kernel places a process's memory regions such as the stack and heap higher than this address, the hardware prevents execution in that address range.

Description

ExecShield uses the segmentation feature on all x86 systems to prevent execution in memory higher than a certain address. It writes an address as a limit in the code segment descriptor, to control where code can be executed, on a per-process basis. When the kernel places a process's memory regions such as the stack and heap higher than this address, the hardware prevents execution in that address range.

STIG	Date
Red Hat Enterprise Linux 6 Security Technical Implementation Guide	2020-09-03

Details

Check Text ( C-19391r376745_chk )
The status of the "kernel.exec-shield" kernel parameter can be queried by running the following command: $ sysctl kernel.exec-shield kernel.exec-shield = 1 $ grep kernel.exec-shield /etc/sysctl.conf /etc/sysctl.d/* kernel.exec-shield = 1 If "kernel.exec-shield" is not configured in the /etc/sysctl.conf file or in the /etc/sysctl.d/ directory, is commented out, or does not have a value of "1", this is a finding.

Check Text ( C-19391r376745_chk )

The status of the "kernel.exec-shield" kernel parameter can be queried by running the following command:

$ sysctl kernel.exec-shield
kernel.exec-shield = 1

$ grep kernel.exec-shield /etc/sysctl.conf /etc/sysctl.d/*
kernel.exec-shield = 1

If "kernel.exec-shield" is not configured in the /etc/sysctl.conf file or in the /etc/sysctl.d/ directory, is commented out, or does not have a value of "1", this is a finding.

Fix Text (F-19389r376746_fix)
To set the runtime status of the "kernel.exec-shield" kernel parameter, run the following command: # sysctl -w kernel.exec-shield=1 Set the system to the required kernel parameter by adding the following line to "/etc/sysctl.conf" or a config file in the /etc/sysctl.d/ directory (or modify the line to have the required value): kernel.exec-shield = 1 Issue the following command to make the changes take effect: # sysctl --system

Fix Text (F-19389r376746_fix)

To set the runtime status of the "kernel.exec-shield" kernel parameter, run the following command:

# sysctl -w kernel.exec-shield=1

Set the system to the required kernel parameter by adding the following line to "/etc/sysctl.conf" or a config file in the /etc/sysctl.d/ directory (or modify the line to have the required value):

kernel.exec-shield = 1

Issue the following command to make the changes take effect:

# sysctl --system