About

Imported from CyberStrikeus/CyberStrike (.cyberstrike/skill/NIST/SP800-53_rev5/SI_system-and-information-integrity/SI-4(21)_probationary-periods/SKILL.md). Install upstream with npx skills add CyberStrikeus/CyberStrike --skill SI-4(21)_probationary-periods. Copyright stays with the author.

SI-4(21) Probationary Periods

Name: SI-4(21)_probationary-periods
Author: CyberStrikeus

Enhancement of: SI-4

High-Level Description

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

During probationary periods, employees do not have permanent employment status within organizations. Without such status or access to information that is resident on the system, additional monitoring can help identify any potentially malicious activity or inappropriate behavior.

What to Check

Verify SI-4(21) Probationary Periods is documented in SSP
Confirm control is operating effectively
Review evidence of continuous monitoring for SI-4(21)
Verify enhancement builds upon base control SI-4

How to Test

Step 1: Review Documentation

Examine the System Security Plan (SSP) and related artifacts for SI-4(21) 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

Implement the following additional monitoring of individuals during [organization-defined]: [organization-defined].

Implementation Guidance

During probationary periods, employees do not have permanent employment status within organizations. Without such status or access to information that is resident on the system, additional monitoring can help identify any potentially malicious activity or inappropriate behavior.

Risk Assessment

Finding	Severity	Impact
SI-4(21) Probationary Periods not implemented	High	System and Information Integrity
SI-4(21) partially implemented	Medium	Incomplete System and Information Integrity

CWE Categories

CWE ID	Title
CWE-20	Improper Input Validation

References

Checklist

Control documented in SSP
Implementation evidence collected
Operating effectiveness validated
Continuous monitoring in place
Related controls (AC-18) reviewed

Use it

Copy one of these into your project. Installing also returns the manifest and these snippets.

yaml

targets:
  - https://api.opensmartroute.ai/api/v1/registry/cyberstrikeus-cyberstrike-si-4-21-probationary-periods/manifest   # or paste the manifest below

Manifest

An Open Capability Manifest: the router reads it to know what this does, what it costs and when to pick it.

cyberstrikeus-cyberstrike-si-4-21-probationary-periods.ocm.jsonjson

{
  "ocm": "1",
  "id": "cyberstrikeus-cyberstrike-si-4-21-probationary-periods",
  "kind": "skill",
  "name": "SI-4(21)_probationary-periods",
  "description": "Implement the following additional monitoring of individuals during [organization-defined]: [organization-defined].",
  "publisher": "CyberStrikeus",
  "version": "1.0.0",
  "capabilities": {
    "domains": [
      "general"
    ],
    "tags": [
      "skill-md",
      "nist",
      "sp800-53",
      "rev5",
      "si-4-21",
      "si",
      "enhancement",
      "github"
    ],
    "languages": [
      "en"
    ]
  },
  "quality_prior": 0.6,
  "examples": [
    "Implement the following additional monitoring of individuals during [organization-defined]: [organization-defined]."
  ],
  "primary": false,
  "metadata": {
    "source": {
      "provider": "github",
      "repository": "https://github.com/CyberStrikeus/CyberStrike",
      "path": ".cyberstrike/skill/NIST/SP800-53_rev5/SI_system-and-information-integrity/SI-4(21)_probationary-periods/SKILL.md",
      "ref": "df28ccd3dc6d6c02391169121ee2dcdf4a6a132b",
      "url": "https://github.com/CyberStrikeus/CyberStrike/blob/df28ccd3dc6d6c02391169121ee2dcdf4a6a132b/.cyberstrike/skill/NIST/SP800-53_rev5/SI_system-and-information-integrity/SI-4(21)_probationary-periods/SKILL.md",
      "key": "CyberStrikeus/CyberStrike/.cyberstrike/skill/NIST/SP800-53_rev5/SI_system-and-information-integrity/SI-4(21)_probationary-periods/SKILL.md"
    }
  },
  "instructions": "# SI-4(21) Probationary Periods\n\n> **Enhancement of:** SI-4\n\n## High-Level Description\n\n**Family:** System and Information Integrity (SI)\n**Framework:** NIST SP 800-53 Rev 5\n\nDuring probationary periods, employees do not have permanent employment status within organizations. Without such status or access to information that is resident on the system, additional monitoring can help identify any potentially malicious activity or inappropriate behavior.\n\n## What to Check\n\n- [ ] Verify SI-4(21) Probationary Periods is documented in SSP\n- [ ] Confirm control is operating effectively\n- [ ] Review ev",
  "cost": {
    "context_tokens": 827
  }
}

Fetch it by URL: GET /api/v1/registry/cyberstrikeus-cyberstrike-si-4-21-probationary-periods/manifest?version=1.0.0

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