NIST SP 800-171 Rev 2 · 3.1 Access Control
3.1.21 Portable storage on external systems
Limit use of portable storage devices on external systems.
- SPRS weight
- 1
- 1 point deducted from 110 when not implemented.
- CMMC level
- L2
- Level 2 only; not among the 17 Level 1 practices.
- Assessment objectives
- 3
- From NIST SP 800-171A, each one a “determine if” an assessor answers.
What an assessor checks
NIST SP 800-171A breaks 3.1.21 into 3 objectives. Every one has to be met for the requirement to be met; a partial answer scores as not implemented.
- [a]Determine if use of organizational portable storage devices containing CUI on external systems is identified and documented.
- [b]Determine if limits on the use of organizational portable storage devices containing CUI on external systems are defined.
- [c]Determine if use of organizational portable storage devices containing CUI on external systems is limited as defined.
- Examine
- [SELECT FROM: Access control policy; procedures addressing the use of external systems; security plan; system configuration settings and associated documentation; system connection or processing agreements; account management documents; other relevant documents or records].
- Interview
- [SELECT FROM: Personnel with responsibilities for restricting or prohibiting use of organization-controlled storage devices on external systems; system or network administrators; personnel with information security responsibilities].
- Test
- [SELECT FROM: Mechanisms implementing restrictions on use of portable storage devices].
If it is open: POA&M eligibility
May be carried on a Level 2 POA&M · 1 point deducted
A 1-point requirement outside the six named exclusions - eligible to carry, and NOT MET until a closeout assessment confirms it.
A POA&M is only permitted at a score of 88 or above, and closes in one 180-day window. Check a full gap list or compute your score.
Where 3.1.21 maps
NIST SP 800-53 Rev 5
- AC-21 Information Sharing
NIST CSF 2.0
- Data-in-use is protected
SOC 2
No direct mapping.
Query it from your own tools
This page and the MacTech CMMC MCP server render the same dataset. Ask your assistant and it will answer from the methodology, not from memory.
lookup_control 3.1.21 get_assessment_objectives 3.1.21 generate_poam_entries ["3.1.21"]
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