MP-3 Media Marking in NIST SP 800-53 Rev 5 asks you to mark system media with distribution limitations, handling caveats and applicable security markings. You may exempt certain media from marking if it stays within a controlled area you define.
800-53 binds US federal systems and, through contracts, some of their suppliers. The guidance refers to controlled unclassified information, a US government category. A commercial company can apply the same idea to its own classes of data.
What it means in practice
If a backup drive holds customer data, a person picking it up should be able to tell. A simple label such as Confidential, Internal or Restricted does the job. The mark should tell people what they may do with the media.
The exemption is useful. Media kept inside a locked server room may not need a label on every disk. Decide where that boundary is and write it down.
Evidence to collect
- The marking scheme and the data classes it uses.
- Photos or samples of marked media.
- The list of exempt media types and the controlled area where they stay.
- The procedure that tells staff how to mark.
Common gaps
Labels exist but no one knows what they mean. Exempt media travel outside the controlled area. Paper is marked and drives are not.
How to implement it
Reuse your data classification policy. Buy label stock, put it in the places where media are created, and teach people in onboarding. Mark on creation, not later.
There are no enhancements for MP-3 in the record.
Quick check
Can any media skip marking?
Yes. The control allows an exemption for media that remain within a controlled area you define.
