SI 3(8) Detect Unauthorized Commands

---
name: "SI-3(8)_detect-unauthorized-commands"
description: "Detect the following unauthorized operating system commands through the kernel application programming interface on [organization-defined]: [organi..."
category: "input-validation"
version: "5.2.0"
author: "cyberstrike-official"
tags:
  - nist
  - sp800-53
  - rev5
  - si-3-8
  - si
  - enhancement
tech_stack:
  - aws
  - azure
  - gcp
  - linux
  - windows
cwe_ids:
  - CWE-20
chains_with:
  - AU-2
  - AU-6
  - AU-12
prerequisites:
  - SI-3
severity_boost:
  AU-2: "Chain with AU-2 for comprehensive security coverage"
  AU-6: "Chain with AU-6 for comprehensive security coverage"
  AU-12: "Chain with AU-12 for comprehensive security coverage"
---

# SI-3(8) Detect Unauthorized Commands

> **Enhancement of:** SI-3

## High-Level Description

**Family:** System and Information Integrity (SI)
**Framework:** NIST SP 800-53 Rev 5

Detecting unauthorized commands can be applied to critical interfaces other than kernel-based interfaces, including interfaces with virtual machines and privileged applications. Unauthorized operating system commands include commands for kernel functions from system processes that are not trusted to initiate such commands as well as commands for kernel functions that are suspicious even though commands of that type are reasonable for processes to initiate. Organizations can define the malicious commands to be detected by a combination of command types, command classes, or specific instances of commands. Organizations can also define hardware components by component type, component, component location in the network, or a combination thereof. Organizations may select different actions for different types, classes, or instances of malicious commands.

## What to Check

- [ ] Verify SI-3(8) Detect Unauthorized Commands is documented in SSP
- [ ] Validate all 2 control requirements are implemented
- [ ] Confirm control is operating effectively
- [ ] Review evidence of continuous monitoring for SI-3(8)
- [ ] Verify enhancement builds upon base control SI-3

## How to Test

### Step 1: Review Documentation

Examine the System Security Plan (SSP) and related artifacts for SI-3(8) 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 integrity monitoring | `cloud_audit_monitoring`       |
| AWS CLI         | Review GuardDuty/Inspector | `aws guardduty list-detectors` |

## Remediation Guide

### Control Statement

Detect the following unauthorized operating system commands through the kernel application programming interface on [organization-defined]: [organization-defined] ; and
[organization-defined].

### Implementation Guidance

Detecting unauthorized commands can be applied to critical interfaces other than kernel-based interfaces, including interfaces with virtual machines and privileged applications. Unauthorized operating system commands include commands for kernel functions from system processes that are not trusted to initiate such commands as well as commands for kernel functions that are suspicious even though commands of that type are reasonable for processes to initiate. Organizations can define the malicious commands to be detected by a combination of command types, command classes, or specific instances of commands. Organizations can also define hardware components by component type, component, component location in the network, or a combination thereof. Organizations may select different actions for different types, classes, or instances of malicious commands.

## Risk Assessment

| Finding                                              | Severity | Impact                                      |
| ---------------------------------------------------- | -------- | ------------------------------------------- |
| SI-3(8) Detect Unauthorized Commands not implemented | High     | System and Information Integrity            |
| SI-3(8) partially implemented                        | Medium   | Incomplete System and Information Integrity |

## CWE Categories

| CWE ID | Title                     |
| ------ | ------------------------- |
| CWE-20 | Improper Input Validation |

## References

- [NIST SP 800-53 Rev 5 - SI-3(8)](https://csrc.nist.gov/projects/cprt/catalog#/cprt/framework/version/SP_800_53_5_1_1/home?element=si-3.8)
- [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 (AU-2, AU-6, AU-12) reviewed