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-38597	RHEL-06-000079	SV-50398r2_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.

STIG	Date
Red Hat Enterprise Linux 6 Security Technical Implementation Guide	2016-12-16

Details

Check Text ( C-46155r3_chk )

The status of the "kernel.exec-shield" kernel parameter can be queried by running the following command: $ sysctl kernel.exec-shield $ grep kernel.exec-shield /etc/sysctl.conf The output of the command should indicate a value of "1". If this value is not the default value, investigate how it could have been adjusted at runtime, and verify it is not set improperly in "/etc/sysctl.conf". If the correct value is not returned, this is a finding.

Fix Text (F-43545r1_fix)
To set the runtime status of the "kernel.exec-shield" kernel parameter, run the following command: # sysctl -w kernel.exec-shield=1 If this is not the system's default value, add the following line to "/etc/sysctl.conf": kernel.exec-shield = 1