cis-ubuntu2004-v300-1-5-1

name	cis-ubuntu2004-v300-1-5-1
description	Ensure address space layout randomization is enabled
category	cis-storage
version	3.0.0
author	cyberstrike-official
tags	["cis","ubuntu","linux","ubuntu-20.04","aslr","kernel","hardening"]
cis_id	1.5.1
cis_benchmark	CIS Ubuntu Linux 20.04 LTS Benchmark v3.0.0
tech_stack	["ubuntu","linux"]
cwe_ids	[]
chains_with	[]
prerequisites	[]
severity_boost	{}

1.5.1 Ensure address space layout randomization is enabled (Automated)

Profile

• Level 1 - Server
• Level 1 - Workstation

Description

Address space layout randomization (ASLR) is an exploit mitigation technique which randomly arranges the address space of key data areas of a process.

Rationale

Randomly placing virtual memory regions will make it difficult to write memory page exploits as the memory placement will be consistently shifting.

Audit Procedure

Command Line

Run the following script to verify the following kernel parameter is set in the running configuration and correctly loaded from a kernel parameter configuration file:

• kernel.randomize_va_space is set to 2

Note: kernel parameters are loaded by file and parameter order precedence. The following script observes this precedence as part of the auditing procedure. The parameters being checked may be set correctly in a file. If that file is superseded, the parameter is overridden by an incorrect setting later in that file, or in a canonically later file, that "correct" setting will be ignored both by the script and by the system during a normal kernel parameter load sequence.

#!/usr/bin/env bash

{
    a_output=(); a_output2=(); a_parlist=(kernel.randomize_va_space=2)
    l_systemdsysctl="$(readlink -f /lib/systemd/systemd-sysctl || readlink -f /usr/lib/systemd/systemd-sysctl)"
    l_ufwscf="$([ -f /etc/default/ufw ] && awk -F= '/^\s*IPT_SYSCTL=/ {print $2}' /etc/default/ufw)"
    f_kernel_parameter_chk()
    {
        l_running_parameter_value="$(sysctl "$l_parameter_name" | awk -F= '{print $2}' | xargs)"
        if grep -Pq -- '\b'"$l_parameter_value"'\b' <<< "$l_running_parameter_value"; then
            a_output+=(" - \"$l_parameter_name\" is correctly set to \"$l_running_parameter_value\"" \
            )
        
            a_output2+=( \
             \
            )
        
        
    }
    
}