si-21-information-refresh

name	SI-21_information-refresh
description	Refresh [organization-defined] at [organization-defined] or generate the information on demand and delete the information when no longer needed.
category	input-validation
version	5.2.0
author	cyberstrike-official
tags	["nist","sp800-53","rev5","si-21","si"]
tech_stack	["aws","azure","gcp","linux","windows"]
cwe_ids	["CWE-20"]
chains_with	["SI-14"]
prerequisites	[]
severity_boost	{"SI-14":"Chain with SI-14 for comprehensive security coverage"}

SI-21 Information Refresh

High-Level Description

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

Retaining information for longer than it is needed makes it an increasingly valuable and enticing target for adversaries. Keeping information available for the minimum period of time needed to support organizational missions or business functions reduces the opportunity for adversaries to compromise, capture, and exfiltrate that information.

What to Check

• Verify SI-21 Information Refresh is documented in SSP
• Confirm control is operating effectively
• Review evidence of continuous monitoring for SI-21

How to Test

Step 1: Review Documentation

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

Refresh [organization-defined] at [organization-defined] or generate the information on demand and delete the information when no longer needed.

Implementation Guidance

Retaining information for longer than it is needed makes it an increasingly valuable and enticing target for adversaries. Keeping information available for the minimum period of time needed to support organizational missions or business functions reduces the opportunity for adversaries to compromise, capture, and exfiltrate that information.

Risk Assessment