# MP-5(3)_custodians

> Employ an identified custodian during transport of system media outside of controlled areas.

- Skill: `cyberstrikeus/mp-5-3-custodians` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/mp-5-3-custodians`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/mp-5-3-custodians/raw
- Safety review: PASS (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: cyberstrikeus (https://skillmd.com/u/cyberstrikeus)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/cyberstrikeus/mp-5-3-custodians

---


# MP-5(3) Custodians

> **Enhancement of:** MP-5

## High-Level Description

**Family:** Media Protection (MP)
**Framework:** NIST SP 800-53 Rev 5

Identified custodians provide organizations with specific points of contact during the media transport process and facilitate individual accountability. Custodial responsibilities can be transferred from one individual to another if an unambiguous custodian is identified.

## What to Check

- [ ] Verify MP-5(3) Custodians is documented in SSP
- [ ] Confirm control is operating effectively
- [ ] Review evidence of continuous monitoring for MP-5(3)
- [ ] Verify enhancement builds upon base control MP-5

## How to Test

### Step 1: Review Documentation

Examine the System Security Plan (SSP) and related artifacts for MP-5(3) implementation details. Verify the organization has documented how this control is satisfied.

### Step 2: Validate Implementation

```
# For cloud environments, use cloud-audit-mcp tools
# For on-premises, review system configurations directly

# Example: Check if account management policies exist
grep -r "account.management\|access.control" /etc/security/ 2>/dev/null
```

### Step 3: Test Operating Effectiveness

Verify the control is actively functioning, not just documented. Check logs, configurations, and operational evidence.

## Tools

| Tool          | Purpose                           | Usage |
| ------------- | --------------------------------- | ----- |
| Manual Review | Documentation and interview-based | N/A   |

## Remediation Guide

### Control Statement

Employ an identified custodian during transport of system media outside of controlled areas.

### Implementation Guidance

Identified custodians provide organizations with specific points of contact during the media transport process and facilitate individual accountability. Custodial responsibilities can be transferred from one individual to another if an unambiguous custodian is identified.

## Risk Assessment

| Finding                            | Severity | Impact                      |
| ---------------------------------- | -------- | --------------------------- |
| MP-5(3) Custodians not implemented | Medium   | Media Protection            |
| MP-5(3) partially implemented      | Low      | Incomplete Media Protection |

## CWE Categories

| CWE ID | Title                 |
| ------ | --------------------- |
| N/A    | No direct CWE mapping |

## References

- [NIST SP 800-53 Rev 5 - MP-5(3)](https://csrc.nist.gov/projects/cprt/catalog#/cprt/framework/version/SP_800_53_5_1_1/home?element=mp-5.3)
- [NIST SP 800-53A Rev 5 (Assessment Procedures)](https://csrc.nist.gov/pubs/sp/800/53/a/r5/final)
- [NIST SP 800-53 Rev 5 Full Catalog](https://csrc.nist.gov/pubs/sp/800/53/r5/upd1/final)

## Checklist

- [ ] Control documented in SSP
- [ ] Implementation evidence collected
- [ ] Operating effectiveness validated
- [ ] Continuous monitoring in place
- [ ] Related controls (none) reviewed