Ubuntu OS must be configured so that the Advance Package Tool (APT) prevents the installation of patches, service packs, device drivers, or operating system components without verification they have been digitally signed using a certificate recognized and approved by the organization.

Changes to any software components can have significant effects on the overall security of the operating system. This requirement ensures the software has not been tampered with and that it has been provided by a trusted vendor.

Accordingly, patches, service packs, device drivers, or operating system components must be signed with a certificate recognized and approved by the organization.

Verifying the authenticity of the software prior to installation validates the integrity of the patch or upgrade received from a vendor. This ensures the software has not been tampered with and that it has been provided by a trusted vendor. Self-signed certificates are disallowed by this requirement. The operating system should not have to verify the software again. This requirement does not mandate DOD certificates for this purpose; however, the certificate used to verify the software must be from an approved certificate authority (CA).

Verify APT is configured to prevent the installation of patches, service packs, device drivers, or Ubuntu operating system components without verification they have been digitally signed using a certificate recognized and approved by the organization by using the following command:

     $ grep -i allowunauthenticated /etc/apt/apt.conf.d/* 
     /etc/apt/apt.conf.d/01-vendor-ubuntu:APT::Get::AllowUnauthenticated "false"; 

If "APT::Get::AllowUnauthenticated" is not set to "false", is commented out, or is missing, this is a finding.

Configure APT to prevent the installation of patches, service packs, device drivers, or Ubuntu operating system components without verification they have been digitally signed using a certificate recognized and approved by the organization.

Add or modify the following line in any file under the "/etc/apt/apt.conf.d/" directory:

APT::Get::AllowUnauthenticated "false";