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


Finding ID Version Rule ID IA Controls Severity
V-217910 RHEL-06-000079 SV-217910r505923_rule Medium
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.
Red Hat Enterprise Linux 6 Security Technical Implementation Guide 2020-09-03


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