Advance package Tool (APT) must remove all software components after updated versions have been installed.

From Canonical Ubuntu 16.04 Security Technical Implementation Guide

Associated with: CCI-002617

SV-90209r1_rule Advance package Tool (APT) must remove all software components after updated versions have been installed.

Vulnerability discussion

Previous versions of software components that are not removed from the information system after updates have been installed may be exploited by adversaries. Some information technology products may remove older versions of software automatically from the information system.

Check content

Verify Advance package Tool (APT) is configured to remove all software components after updated versions have been installed. Check that APT is configured to remove all software components after updating with the following command: # grep -i remove-unused /etc/apt/apt.conf.d/50unattended-upgrades Unattended-Upgrade::Remove-Unused-Dependencies "true"; If the "Remove-Unused-Dependencies" parameter is not set to "true", or is missing, this is a finding.

Fix text

Configure APT to remove all software components after updated versions have been installed. Add or updated the following option to the "/etc/apt/apt.conf.d/50unattended-upgrades" file: Unattended-Upgrade::Remove-Unused-Dependencies "true";

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