RHEL 9 must have GPG signature verification enabled for all software repositories.

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.

All software packages must be signed with a cryptographic key recognized and approved by the organization.

Verifying the authenticity of software prior to installation validates the integrity of the software package received from a vendor. This verifies the software has not been tampered with and that it has been provided by a trusted vendor.

Verify RHEL 9 software repositories defined in "/etc/yum.repos.d/" have been configured with "gpgcheck" enabled with the following command:

$ sudo grep -w gpgcheck /etc/yum.repos.d/*.repo | more gpgcheck = 1

If "gpgcheck" for software packages and repositories is not set to either "1", "true", or "yes" (keywords containing letters are case insensitive), or if the option is missing or commented out, ask the system administrator how the GPG signatures of local software packages are being verified.

If no process to verify GPG signatures has been approved by the organization, this is a finding.

Configure RHEL 9 software repositories defined in "/etc/yum.repos.d/" to have "gpgcheck" enabled with the following command:

$ sudo sed -i 's/gpgcheck\s*=.*/gpgcheck=1/g' /etc/yum.repos.d/*

Note: Any of the following are acceptable: "1", "true", or "yes" (keywords containing letters are case insensitive).