SV-219342r958928: The Ubuntu operating system must implement address space layout randomization to protect its memory from unauthorized code execution. | Canonical Ubuntu 18.04 LTS STIG SCAP Benchmark

Loading benchmark…

Assessment Title

Rule Text

The Ubuntu operating system must implement address space layout randomization to protect its memory from unauthorized code execution.

Description

Discussion Text

Some adversaries launch attacks with the intent of executing code in non-executable regions of memory or in memory locations that are prohibited. Security safeguards employed to protect memory include, for example, data execution prevention and address space layout randomization. Data execution prevention safeguards can either be hardware-enforced or software-enforced with hardware providing the greater strength of mechanism. Examples of attacks are buffer overflow attacks.

How this relates to the STIG checklist: STIG vs SCAP benchmark.

IA Controls

NIST SP 800-53

Not mappedCCI-002824SV-110009V-100905

References

DPMS Target Canonical Ubuntu 18.04 LTS DISA DPMS Target Canonical Ubuntu 18.04 LTS 4055

Checks

DISA STIG (Manual Reference)

Verify the Ubuntu operating system implements address space layout randomization (ASLR).

Check that ASLR is configured on the system with the following command:

# sudo sysctl kernel.randomize_va_space

kernel.randomize_va_space = 2

Verify the kernel parameter "randomize_va_space" is set to 2 with the following command:

# cat /proc/sys/kernel/randomize_va_space

2

If "kernel.randomize_va_space" is not set to 2, this is a finding.

Check the saved value of the kernel.randomize_va_space variable is not different from 2.

# sudo egrep -R "^kernel.randomize_va_space=[^2]" /etc/sysctl.conf /etc/sysctl.d

If this returns a result, this is a finding.

SCC Automation Reference

The reconstructed evaluation script behind this rule's OVAL check(s) — every module a compound check combines, with this rule's own concrete values and DISA's SCC tool's real per-module mechanism curated from static teardown of SCC releases.

#!/bin/bash
# Reconstructed from oval:mil.disa.stig.ubuntu1804:def:273
# The Ubuntu operating system must implement address space layout randomization to protect its memory from unauthorized code execution.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.
#
# MANUAL REVIEW REQUIRED -- the module(s) below could not be reconstructed
# into working code from curated SCC reference data, and are excluded from
# the automated result:
#   - textfilecontent54_object (textfilecontent54_test) -- kernel.randomize_va_space setting in sysctl configuration files is set to 2, and nothing else: <set> composition (base object oval:mil.disa.stig.ubuntu1804:obj:27301, oval:mil.disa.stig.ubuntu1804:obj:27302): member unresolved -- no extractor for field "subexpression"

# kernel.randomize_va_space setting in kernel is set to 2
# sysctl_object (sysctl_test)
test_1() {
  [ "$(cat /proc/sys/kernel/randomize_va_space)" -eq 2 ]
}

if test_1; then
  echo "PASS (automated portion only -- MANUAL REVIEW still required, see notes above)"
else
  echo "FAIL (or see MANUAL REVIEW note above)"
fi

Assessment Script Powered by AISandbox-executed

A standalone Shell script to assess this control automatically. Review before running it in your environment.

Syntax-checked and actually executed in an isolated sandbox (not the real system this checks) — confirmed to run without errors.

#!/bin/sh
# OVAL Definition: oval:mil.disa.stig.ubuntu1804:def:273

if [ ! -f "/etc/sysctl.conf" ]; then
    echo "PASS"
    exit 0
fi

grep -q "^kernel\.randomize_va_space *= *[01]$" /etc/sysctl.conf || {
    echo "FAIL"
    exit 1
}

sysctl -n kernel.randomize_va_space | grep -q '^2$' || {
    echo "FAIL"
    exit 1
}

echo "PASS"
exit 0

Remediation

Set the "kernel.randomize_va_space" entry found in the "/etc/sysctl.conf" file to a value of "2".

After the line has been modified the kernel settings from all system configuration files must be reloaded; before any of the changes will take effect. 

Run the following command to reload all of the kernel system configuration files:

# sudo sysctl --system