When you cut through the marketing hype—and ignore all of the LinkedIn trolls predicting the doom of the Cybersecurity Maturity Model Certification (CMMC) program— you realize CMMC did not arise out of the blue. When you reasearch its history, you will find nothing especially new or unfamiliar. CMMC simply requires third party attestation of what defense contractors already had to do in order to fulfill the legal requirements of their agreements. The major change associated with CMMC is that it no longer allows for the self-assessment of cyber hygiene associated with Controlled Unclassified Information (CUI), as measured against NIST-SP-800-171 “Protecting Controlled Unclassified Information in Nonfederal Systems and Organizations.”

Individual contractors no longer have the authority to say how well they secure CUI. Instead, a third pary must come in and assess this information. In essence, it all comes down to CUI. But what do we mean we say Controlled Unclassified Information (CUI)?

What is CUI?

The US Government defines CUI as information which requires safeguarding or dissemination controls necessitated by law, regulation, or Government-Wide Policy; however, it does not include classified or nuclear stuff. The latter two fall under classified policies, and therefore require even more protections than CUI.

The CUI program is thoroughly explained in the Code of Federal Regulation 32, Part 2002. This program standardizes how the Executive Branch handles CUI. The Department of Defense (DoD), for example, established a CUI policy on March 6th 2002. This policy, DoD Instruction 5200.48, “Controlled Unclassified Information,” fulfills their requirements to develop a CUI policy. Every department, and thus their respective agencies, must have a similar CUI policy.

The CUI designation was created in response to 9/11 via President Obama’s Executive Order 13556. This executive order required all unclassified information throughout the Executive Branch which necessitated additional protection above and beyond information not for public release to be labeled CUI. Before this CUI policy, no uniform marking system existed for this kind of information across the Federal Government. Different agencies used an alphabet soup of labels such as FOUO, LES, and SBU.

Under the Executive Order, the National Archives and Record Administration (NARA) was appointed to lead on developing a universal CUI Policy. The Secretary of Commerce, through the Office of Management and Budget, decided that CUI required moderate protection. FISMA, the Federal Information Modernization Security Act, then authorized the National Institute of Standards and Technologies (NIST) to develop standards for the protection of CUI.

In fact, section two of the Executive Order designated NARA as the Executive Agency to oversee the order and the CUI program. NARA delegated this authority to the Information Security Oversight Office (ISOO). ISOO established a CUI registry that is:

  • Publicly Accessible
  • Includes authorized categories
  • Includes subcategories and guidance
  • Includes citations to laws and regulation and government wide policies

The Department of Defense then defined their relevant categories using DoD Instruction 5200.48, “Controlled Unclassified Information”.

The ISOO CUI policy defines two types of CUI: Basic and Specified. Specified CUI contains specific handling controls, which it requires or permits agencies to use, and which differ from those used for Basic CUI. So, if a federal law or regulation requires handling instructions beyond the basic protections of CUI, we call this CUI Specified. An agency can decide internally, or with agreement from ISOO, to require additional protections.

CUI Lifecycle

The CUI lifecycle requires a contractor to identify the CUI they handle, to explicitly mark this data as CUI, to protect this CUI while in transit and at rest, to only share CUI for a lawful purpose, to destroy CUI when necessary, and to decontrol CUI when it no longer needs additional security.

Identifying CUI

It is best to begin this process by determining if you have any CUI in your system, or if you wish to bid on future contracts that would require CUI in your systems. Unfortunately, most of the data contractors receive from the DoD and prime contractors will not have proper markings. This does no alleviate a contractor of the legal responsibilities for protecting CUI, especially if they have existing contracts with the Defense Federal Acquisition Regulation Supplemental (DFARS) clause 7012, which requires self-attestation for protecting CUI against a 171 baseline.

Once you identify the CUI in your system, identify which contract vehicles with a 7012 clause the CUI is often associated with. Then identify the people or roles with legal access to that CUI under each contract. In fact, you should create a matrix to capture this information.

You cannot expect the DoD or a prime contractor to label all CUI created under a CUI contract. How could a Contracting Officer (CO) or a Program Management Office decide if the personal notes taken or meeting minutes contain CUI?

Marking CUI

The CUI program set out to protect unclassified information and ensure the timely sharing of information. The marking requirements of CUI vary based on the kinds of CUI and the chosen designation indicator. These influence the requirements for banner markings, which have to include category markings, control markings, and any limited dissemination markings (only certain people should see this).

CUI marking requirements are influenced by more than just their category and control markings. The type of media it is associated with, such as emails or military documents, can influence the marking as well. Email banners may differ from the requirements for removable media. CUI can also be co-mingled into documents that require different limited dissemination, or are considered classified. Finally, you also have rules about marking CUI for mailing.

The marking must include a designation indicator. This indicates who created the CUI. This can include a variety of formats such as a letterhead, a logo on a sticker, a signature, or a controlled byline. You have no requirement to include contact information, but many markings add this optional information.

Department of Defense guidance suggests using a Designation Indicator block when space allows. This includes who controls the data, as well as anyone to which control was flowed through an authorized and legal use, any limited dissemination controls, and a point of contact. For example:

Controlled by: OUSD(I&S)

Controlled by: CL&S INFOSECCUI Category(ies): PRVCY, OPSEC

Limited Dissemination Control: FEDCON

POC: John Brown, 703-555-0123

The banner marking can include three elements. The first, the control marking, is mandatory. This can say “controlled” or “CUI.” Category markings are required for CUI Specified, and are separated by two // slashes. If dissemination controls are included, those follow the category markings, again after two forward slashes. Banners must appear in Bold Capitalized text, and ought to be centered when possible.

CUI works as a basic CUI label.

Category markings are optional, except in the case of CUI Specified. In fact, when you have Specified CUI, you are required to include the letters SP before the category marking. If more then one type of specified marking is included, you alphabetize them, but only separate each by one / forward slash after the first category, which follows the two // forward slashes and the basic marking.

CUI//SP-HLTH/PHYS In this example we see two CUI specified categories which follow the basic CUI marking.

The banner markings can also designate the dissemination controls. Limited Dissemination Controls identify an intended audience, so a document does not need continuous authorization.

No Foreign Dissemination (NOFORN) —Information may not be disseminated in any form to foreign governments, foreign nationals, foreign or international organizations, or non-U.S. citizens.

Federal Employees Only (FED ONLY) —Dissemination authorized only to employees of the U.S. Government executive branch agencies, or armed forces personnel of the U.S. or Active Guard and Reserve.

Federal Employees and Contractors Only (FEDCON) —Includes individuals or employees who enter a contract with the U.S. to perform a specific job or supply labor, and dissemination is in furtherance of the contractual purpose.

No Dissemination to Contractors (NOCON) —Intended for use when dissemination is not permitted to federal contractors, but permits dissemination to state, local, or tribal employees.

Dissemination List Controlled DL ONLY —Dissemination authorized only to those individuals, organizations, or entities included on an accompanying dissemination list.

Authorized for Release to Certain Foreign Nationals Only (REL TO USA, LIST) —Information has been predetermined by the designating agency to be releasable only to the foreign country(ies) or international organization(s) indicated, through established foreign disclosure procedures and channels.

The Department of Defense CUI guidance also allows dissemination marking to be included in the designation box. These include:

Distribution Statement A: Approved for public release. Distribution is unlimited.

Distribution Statement B: Distribution authorized to U.S. Government agencies only (fill in reason and date of determination).

Distribution Statement C: Distribution authorized to U.S. Government agencies and their contractors (fill in reason and date of determination). Other requests for this document shall be referred to (insert controlling DoD office).

Distribution Statement D: Distribution authorized to Department of Defense and U.S. DoD contractors only (insert reason and date of determination). Other requests for this document shall be referred to (insert controlling DoD office).

Distribution Statement E: Distribution authorized to DoD Components only (fill in reason and date of determination). Other requests shall be referred to (insert controlling DoD office).

Distribution Statement F: Further dissemination only as directed by (insert controlling DoD Office and date of determination) or higher DoD authority.

On digital media, you include these markings. On PowerPoint slides, you can include the CUI label at the top and bottom of the title slide with the indication block and the CUI label on the bottom of each slide. In a word document, you can include a cover sheet with the marking and designation block.

Removable Media

On a removable storage device, you are required to include the basic marking and a controlling indicators. Each file contained on the storage device needs its own marking. When feasible, you should include all required elements in the designation block, but the CUI basic marking and the originator or controller must always be included.


Email is a bit trickier. When you send an email (try not to) containing CUI, you must let the recipient know. You must include a banner marking in the body of the email. Furthemore, best practice suggests including it in the CUI itself. Many companies use email server rules to sequester email with CUI. The subject line helps protect the data. When you forward email you must keep all banner markings. Make sure you cut and paste the banner to the top of the forward. You can also portion mark emails like regular documents where you call out sections that contain CUI.

Physical Protection of CUI

You will need to create a controlled environment to protect CUI. The regulations require you to have at least one physical barrier, such as sealed envelopes, locked doors, bins, drawers, or electronic locks. You have flexibility in deciding what counts as a physical barrier.

You also need to consider meeting areas. You will need to control meeting access when CUI is shared and discussed. You will need to mark the door with the lock, noting only authorized indivduals allowed, and you will need a clean desk policy for after the meeting.

Think about who has access to your controlled environments. You will need to lock away CUI from after hour cleaning crews, and to keep visitor and employee logs of areas that contain or discuss CUI. Your computer systems and networks also need to control access. You need to include banner markings on devices and systems that can connect to controlled environments.

Basically, on electronic systems, you need to create some kind of barrier to prevent unauthorized access to CUI. This can include network folders, files, intranet, cloud enclaves, file sharing sites, and individual machines or devices.

Encryption and CUI

Based on Office of Management and Budget (OMB) policy, CUI requires moderate protection. This, in turn, requires encryption which meets a specific level called FIPS Validated 140-2A. At the simplest definition, encryption means that something we read in plain text is scrambled into a cyphertext. The authorized holder then has a “key” to unscramble the ciphertext into plain text.

The approved encryption techniques are authorized by NIST in a document called “Federal Information Processing Standards (FIPS) 140-2.” The approved techniques, which can change based on use case and authorizer, include: AES, Triple-DES, and the Digital Signature Standard (“DSS”). NIST-SP-800-171 (3.1.13 and 3.13.11) and CMMC spell out specific requirements for encryption (AC.3.014, SC.3.177).

With FIPs level encryption, we make an important distinction between modules and devices. A module can be an embedded part of a product, such as an “encrypt this email” button or an entire product such as a CUI cloud enclave. A device, such as a laptop or cellphone, does not itself need the encryption. The tool accessed on that device to share, view, store, or transmit CUI must use encryption modules that meet FIPS standards.

Destroying CUI

When you destroy CUI, the NARA policy CFR 32 Part 2002 requires the CUI to end up unreadable, indecipherable, and irreconcilable. The NARA policy follows guidance of National Institute of Standards and Technology (NIST) Special Publication (SP) 800-88, Revision l: “Guidelines for Media Sanitization” or any technique approved by Classified National Security Information (32 CFR 2001.47).

In 2019, NARA released guidance on destroying paper-based CUI. You must follow the specifics of NIST-SP-800-88 when shredding paper. You must crosscut, meaning up and down, and left and right, down to 1mm x 5mm (0.04in x 0.2in) in size. You can also pulverize paper using disintegrator devices equipped with a 3/32in pulverizer. The approved shredders can get expensive. Many companies use a third party shredder or recycler that will provide a certification that they meet the requirements of NIST-SP-800-88.

You can always go the cheapest route and follow the burn recommendations.

In terms of media, there are also destruction requirements. NIST SP 800-171 3.8.3 states, “Sanitize or destroy system media containing CUI before disposal or release for reuse.” The type of media will determine how you sanitize the device. Hard drives, for example, need different disposal methods than static hard drives.

Decontrolling CUI

CFR 32 Part 2002 defines decontrolling as the event in which the authorizing agency decides the CUI “no longer requires such controls.” You must have policies and procedure in place to decontrol CUI. CUI can be decontrolled automatically or through positive decontrol. In automotive decontrol, a prior event, such as a date, is chosen when the controls are no longer required by law or policy. In positive decontrol, the authorizing agency takes an action to remove the controls.

While a contractor can be appointed by the authorizing agency to disagree with the ability to decontrol CUI on a contract with the 7012 clause, it will not happen often.

In the end, when you think CMMC, just think about CUI and how you can protect it from unauthorized disclosure.