Establish and maintain an authoritative source and repository to provide a trusted source and accountability for approved and implemented system components.
The establishment and maintenance of an authoritative source and repository includes a system component inventory of approved hardware, software, and firmware; approved system baseline configurations and configuration changes; and verified system software and firmware, as well as images and/or scripts. The authoritative source implements integrity controls to log changes or attempts to change software, configurations, or data in the repository. Additionally, changes to the repository are subject to change management procedures and require authentication of the user requesting the change. In certain situations, organizations may also require dual authorization for such changes. Software changes are routinely checked for integrity and authenticity to ensure that the changes are legitimate when updating the repository and when refreshing a system from the known, trusted source. The information in the repository is used to demonstrate adherence to or identify deviation from the established configuration baselines and to restore system components from a trusted source. From an automated assessment perspective, the system description provided by the authoritative source is referred to as the desired state. The desired state is compared to the actual state to check for compliance or deviations. [NIST SP 800-128] provides guidance on security configuration management, including security configuration settings and configuration change control.
[NIST IR 8011-1] provides guidance on automation support to assess system and system component configurations.
Trusted software, whether securely developed in house or obtained from a trusted source, should have baseline data integrity established when first created or obtained, such as by using hash algorithms to obtain a hash value that would be used to validate the source prior to use of the software in a given system. Hardware in the repository should be stored in boxes or containers with tamper-evident seals. Hashes and seals should be checked on a regular basis employing the principle of separation of duties.
You are the primary system build technician at a medium-sized company. You have been put in charge of creating, documenting, and implementing a baseline configuration for all user systems [c]. You have identified a minimum set of software that is needed by all employees to complete their work (e.g., office automation software). You acquire trusted versions of the software and build one or more baselines of all system software, firmware, and applications required by the organization. The gold version of each baseline is stored in a secure configuration management system repository and updated as required to maintain integrity and security. Access to the build repository for updates and use is carefully controlled using access control mechanisms that limit access to you and your staff. All interations with the repository are logged. Using an automated build tool, your team builds each organizational system using the standard baseline
Potential Assessment Considerations
- Does an authoritative source and repository exist to provide a trusted source and accountability for approved and implemented system components [c,d]?