AC-2(12)_account-monitoring-for-atypical-usage

DevOps & Security

Monitor system accounts for [organization-defined] ;

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Source SKILL.md: https://github.com/CyberStrikeus/CyberStrike/blob/HEAD/.cyberstrike/skill/NIST/SP800-53_rev5/AC_access-control/AC-2(12)_account-monitoring-for-atypical-usage/SKILL.md

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AC-2(12) Account Monitoring for Atypical Usage

Enhancement of: AC-2

High-Level Description

Family: Access Control (AC) Framework: NIST SP 800-53 Rev 5

Atypical usage includes accessing systems at certain times of the day or from locations that are not consistent with the normal usage patterns of individuals. Monitoring for atypical usage may reveal rogue behavior by individuals or an attack in progress. Account monitoring may inadvertently create privacy risks since data collected to identify atypical usage may reveal previously unknown information about the behavior of individuals. Organizations assess and document privacy risks from monitoring accounts for atypical usage in their privacy impact assessment and make determinations that are in alignment with their privacy program plan.

What to Check

Verify AC-2(12) Account Monitoring for Atypical Usage is documented in SSP
Validate all 2 control requirements are implemented
Confirm control is operating effectively
Review evidence of continuous monitoring for AC-2(12)
Verify enhancement builds upon base control AC-2

How to Test

Step 1: Review Documentation

Examine the System Security Plan (SSP) and related artifacts for AC-2(12) 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 IAM policies and access controls	`cloud_audit_iam_policies`
hackbrowser-mcp	Test web application access controls	`browser_auth_test`

Remediation Guide

Control Statement

Monitor system accounts for [organization-defined] ; and Report atypical usage of system accounts to [organization-defined].

Implementation Guidance

Atypical usage includes accessing systems at certain times of the day or from locations that are not consistent with the normal usage patterns of individuals. Monitoring for atypical usage may reveal rogue behavior by individuals or an attack in progress. Account monitoring may inadvertently create privacy risks since data collected to identify atypical usage may reveal previously unknown information about the behavior of individuals. Organizations assess and document privacy risks from monitoring accounts for atypical usage in their privacy impact assessment and make determinations that are in alignment with their privacy program plan.

Risk Assessment

Finding	Severity	Impact
AC-2(12) Account Monitoring for Atypical Usage not implemented	High	Access Control
AC-2(12) partially implemented	Medium	Incomplete Access Control

CWE Categories

CWE ID	Title
CWE-284	Improper Access Control

References

Checklist

Control documented in SSP
Implementation evidence collected
Operating effectiveness validated
Continuous monitoring in place
Related controls (AU-6, AU-7, CA-7, IR-8, SI-4) reviewed