# SC-3(2)_access-and-flow-control-functions

> Isolate security functions enforcing access and information flow control from nonsecurity functions and from other security functions.

- Skill: `cyberstrikeus/sc-3-2-access-and-flow-control-functions` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/sc-3-2-access-and-flow-control-functions`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/sc-3-2-access-and-flow-control-functions/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-3-2-access-and-flow-control-functions

---


# SC-3(2) Access and Flow Control Functions

> **Enhancement of:** SC-3

## High-Level Description

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

Security function isolation occurs because of implementation. The functions can still be scanned and monitored. Security functions that are potentially isolated from access and flow control enforcement functions include auditing, intrusion detection, and malicious code protection functions.

## What to Check

- [ ] Verify SC-3(2) Access and Flow Control Functions is documented in SSP
- [ ] Confirm control is operating effectively
- [ ] Review evidence of continuous monitoring for SC-3(2)
- [ ] 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(2) 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

Isolate security functions enforcing access and information flow control from nonsecurity functions and from other security functions.

### Implementation Guidance

Security function isolation occurs because of implementation. The functions can still be scanned and monitored. Security functions that are potentially isolated from access and flow control enforcement functions include auditing, intrusion detection, and malicious code protection functions.

## Risk Assessment

| Finding                                                   | Severity | Impact                                          |
| --------------------------------------------------------- | -------- | ----------------------------------------------- |
| SC-3(2) Access and Flow Control Functions not implemented | High     | System and Communications Protection            |
| SC-3(2) 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(2)](https://csrc.nist.gov/projects/cprt/catalog#/cprt/framework/version/SP_800_53_5_1_1/home?element=sc-3.2)
- [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