# SC-3(3)_minimize-nonsecurity-functionality

> Minimize the number of nonsecurity functions included within the isolation boundary containing security functions.

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

---


# SC-3(3) Minimize Nonsecurity Functionality

> **Enhancement of:** SC-3

## High-Level Description

**Family:** System and Communications Protection (SC)
**Framework:** NIST SP 800-53 Rev 5

Where it is not feasible to achieve strict isolation of nonsecurity functions from security functions, it is necessary to take actions to minimize nonsecurity-relevant functions within the security function boundary. Nonsecurity functions contained within the isolation boundary are considered security-relevant because errors or malicious code in the software can directly impact the security functions of systems. The fundamental design objective is that the specific portions of systems that provide information security are of minimal size and complexity. Minimizing the number of nonsecurity functions in the security-relevant system components allows designers and implementers to focus only on those functions which are necessary to provide the desired security capability (typically access enforcement). By minimizing the nonsecurity functions within the isolation boundaries, the amount of code that is trusted to enforce security policies is significantly reduced, thus contributing to understandability.

## What to Check

- [ ] Verify SC-3(3) Minimize Nonsecurity Functionality is documented in SSP
- [ ] Confirm control is operating effectively
- [ ] Review evidence of continuous monitoring for SC-3(3)
- [ ] Verify enhancement builds upon base control SC-3

## How to Test

### Step 1: Review Documentation

Examine the System Security Plan (SSP) and related artifacts for SC-3(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                                |
| --------------- | ------------------------------------- | ------------------------------------ |
| cloud-audit-mcp | Check encryption and network controls | `cloud_audit_encryption`             |
| nmap            | Network scanning                      | `nmap -sV --script ssl-enum-ciphers` |

## Remediation Guide

### Control Statement

Minimize the number of nonsecurity functions included within the isolation boundary containing security functions.

### Implementation Guidance

Where it is not feasible to achieve strict isolation of nonsecurity functions from security functions, it is necessary to take actions to minimize nonsecurity-relevant functions within the security function boundary. Nonsecurity functions contained within the isolation boundary are considered security-relevant because errors or malicious code in the software can directly impact the security functions of systems. The fundamental design objective is that the specific portions of systems that provide information security are of minimal size and complexity. Minimizing the number of nonsecurity functions in the security-relevant system components allows designers and implementers to focus only on those functions which are necessary to provide the desired security capability (typically access enforcement). By minimizing the nonsecurity functions within the isolation boundaries, the amount of code that is trusted to enforce security policies is significantly reduced, thus contributing to understandability.

## Risk Assessment

| Finding                                                    | Severity | Impact                                          |
| ---------------------------------------------------------- | -------- | ----------------------------------------------- |
| SC-3(3) Minimize Nonsecurity Functionality not implemented | High     | System and Communications Protection            |
| SC-3(3) partially implemented                              | Medium   | Incomplete System and Communications Protection |

## CWE Categories

| CWE ID  | Title                                |
| ------- | ------------------------------------ |
| CWE-311 | Missing Encryption of Sensitive Data |

## References

- [NIST SP 800-53 Rev 5 - SC-3(3)](https://csrc.nist.gov/projects/cprt/catalog#/cprt/framework/version/SP_800_53_5_1_1/home?element=sc-3.3)
- [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