SC 11 Trusted Path

---
name: "SC-11_trusted-path"
description: "Provide a [organization-defined] isolated trusted communications path for communications between the user and the trusted components of the system;"
category: "configuration"
version: "5.2.0"
author: "cyberstrike-official"
tags:
  - nist
  - sp800-53
  - rev5
  - sc-11
  - sc
tech_stack:
  - aws
  - azure
  - gcp
  - linux
  - windows
  - network
cwe_ids:
  - CWE-311
chains_with:
  - AC-16
  - AC-25
  - SC-12
  - SC-23
prerequisites: []
severity_boost:
  AC-16: "Chain with AC-16 for comprehensive security coverage"
  AC-25: "Chain with AC-25 for comprehensive security coverage"
  SC-12: "Chain with SC-12 for comprehensive security coverage"
---

# SC-11 Trusted Path

## High-Level Description

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

Trusted paths are mechanisms by which users can communicate (using input devices such as keyboards) directly with the security functions of systems with the requisite assurance to support security policies. Trusted path mechanisms can only be activated by users or the security functions of organizational systems. User responses that occur via trusted paths are protected from modification by and disclosure to untrusted applications. Organizations employ trusted paths for trustworthy, high-assurance connections between security functions of systems and users, including during system logons. The original implementations of trusted paths employed an out-of-band signal to initiate the path, such as using the <BREAK> key, which does not transmit characters that can be spoofed. In later implementations, a key combination that could not be hijacked was used (e.g., the <CTRL> + <ALT> + <DEL> keys). Such key combinations, however, are platform-specific and may not provide a trusted path implementation in every case. The enforcement of trusted communications paths is provided by a specific implementation that meets the reference monitor concept.

## What to Check

- [ ] Verify SC-11 Trusted Path is documented in SSP
- [ ] Validate all 2 control requirements are implemented
- [ ] Confirm control is operating effectively
- [ ] Review evidence of continuous monitoring for SC-11

## How to Test

### Step 1: Review Documentation

Examine the System Security Plan (SSP) and related artifacts for SC-11 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

Provide a [organization-defined] isolated trusted communications path for communications between the user and the trusted components of the system; and
Permit users to invoke the trusted communications path for communications between the user and the following security functions of the system, including at a minimum, authentication and re-authentication: [organization-defined].

### Implementation Guidance

Trusted paths are mechanisms by which users can communicate (using input devices such as keyboards) directly with the security functions of systems with the requisite assurance to support security policies. Trusted path mechanisms can only be activated by users or the security functions of organizational systems. User responses that occur via trusted paths are protected from modification by and disclosure to untrusted applications. Organizations employ trusted paths for trustworthy, high-assurance connections between security functions of systems and users, including during system logons. The original implementations of trusted paths employed an out-of-band signal to initiate the path, such as using the <BREAK> key, which does not transmit characters that can be spoofed. In later implementations, a key combination that could not be hijacked was used (e.g., the <CTRL> + <ALT> + <DEL> keys). Such key combinations, however, are platform-specific and may not provide a trusted path implementation in every case. The enforcement of trusted communications paths is provided by a specific implementation that meets the reference monitor concept.

## Risk Assessment

| Finding                            | Severity | Impact                                          |
| ---------------------------------- | -------- | ----------------------------------------------- |
| SC-11 Trusted Path not implemented | High     | System and Communications Protection            |
| SC-11 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-11](https://csrc.nist.gov/projects/cprt/catalog#/cprt/framework/version/SP_800_53_5_1_1/home?element=sc-11)
- [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 (AC-16, AC-25, SC-12, SC-23) reviewed