DISCUSSION [NIST SP 800-171 R2]

Any changes to the hardware, software, or firmware components of systems can potentially have significant effects on the overall security of the systems. Therefore, organizations permit only qualified and authorized individuals to access systems for purposes of initiating changes, including upgrades and modifications. Access restrictions for change also include software libraries. Access restrictions include physical and logical access control requirements, workflow automation, media libraries, abstract layers (e.g., changes implemented into external interfaces rather than directly into systems), and change windows (e.g., changes occur only during certain specified times). In addition to security concerns, commonly-accepted due diligence for configuration management includes access restrictions as an essential part in ensuring the ability to effectively manage the
configuration.

NIST SP 800-128 provides guidance on configuration change control.

FURTHER DISCUSSION

Define, identify, and document qualified individuals authorized to make physical and logical changes to the organization’s hardware, software, software libraries, or firmware components. Control of configuration management activities may involve:

physical access control that prohibits unauthorized users from gaining physical access to an asset (e.g., requiring a special key card to enter a server room);

logical access control that prevents unauthorized users from logging onto a system to make configuration changes (e.g., requiring specific credentials for modifying configuration settings, patching software, or updating software libraries);

workflow automation in which configuration management workflow rules define human tasks and data or files are routed between people authorized to do configuration management based on pre-defined business rules (e.g., passing an electronic form to a manager requesting approval of configuration change made by an authorized employee);

an abstraction layer for configuration management that requires changes be made from an external system through constrained interface (e.g., software updates can only be made from a patch management system with a specific IP address); and

utilization of a configuration management change window (e.g., software updates are only allowed between 8:00 AM and 10:00 AM or between 6:00 PM and 8:00 PM).

Example

Your datacenter requires expanded storage capacity in a server. The change has been approved, and security is planning to allow an external technician to access the building at a specific date and time under the supervision of a manager [a,b,c,d]. A system administrator creates a temporary privileged account that can be used to log into the server’s operating system and update storage settings [e,f,g]. On the appointed day, the technician is escorted into the datacenter, upgrades the hardware, expands the storage in the operating system (OS), and departs. The manager verifies the upgrade and disables the privileged account [h].

Potential Considerations

Are only employees who are approved to make physical or logical changes on systems allowed to do so [a,d,e,h]? 24

Are authorized personnel approved and documented by the service owner and IT security [a,e]? 25

Does all change documentation include the name of the authorized employee making the change [b,d,f,h]? 26

Copyright

Copyright 2020, 2021 Carnegie Mellon University and The Johns Hopkins University Applied Physics Laboratory LLC.

Copyright 2021 Futures, Inc.

This material is based upon work funded and supported by the Department of Defense under Contract No. FA8702-15-D-0002 with Carnegie Mellon University for the operation of the Software Engineering Institute, a federally funded research and development center, and under Contract No. HQ0034-13-D-0003 and Contract No. N00024-13-D-6400 with the Johns Hopkins University Applied Physics Laboratory LLC, a University Affiliated Research Center.

The view, opinions, and/or findings contained in this material are those of the author(s) and should not be construed as an official Government position, policy, or decision, unless designated by other documentation.

NO WARRANTY. THIS MATERIAL IS FURNISHED ON AN “AS-IS” BASIS. CARNEGIE MELLON UNIVERSITY AND THE JOHNS HOPKINS UNIVERSITY APPLIED PHYSICS LABORATORY LLC MAKE NO WARRANTIES OF ANY KIND, EITHER EXPRESSED OR IMPLIED, AS TO ANY MATTER INCLUDING, BUT NOT LIMITED TO, WARRANTY OF FITNESS FOR PURPOSE OR MERCHANTABILITY, EXCLUSIVITY, OR RESULTS OBTAINED FROM USE OF THE MATERIAL NOR ANY WARRANTY OF ANY KIND WITH RESPECT TO FREEDOM FROM PATENT, TRADEMARK, OR COPYRIGHT INFRINGEMENT.