AC 10 Concurrent Session Control

---
name: "AC-10_concurrent-session-control"
description: "Limit the number of concurrent sessions for each [organization-defined] to [organization-defined]."
category: "authorization"
version: "5.2.0"
author: "cyberstrike-official"
tags:
  - nist
  - sp800-53
  - rev5
  - ac-10
  - ac
tech_stack:
  - aws
  - azure
  - gcp
  - linux
  - windows
cwe_ids:
  - CWE-284
chains_with:
  - SC-23
prerequisites: []
severity_boost:
  SC-23: "Chain with SC-23 for comprehensive security coverage"
---

# AC-10 Concurrent Session Control

## High-Level Description

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

Organizations may define the maximum number of concurrent sessions for system accounts globally, by account type, by account, or any combination thereof. For example, organizations may limit the number of concurrent sessions for system administrators or other individuals working in particularly sensitive domains or mission-critical applications. Concurrent session control addresses concurrent sessions for system accounts. It does not, however, address concurrent sessions by single users via multiple system accounts.

## What to Check

- [ ] Verify AC-10 Concurrent Session Control is documented in SSP
- [ ] Confirm control is operating effectively
- [ ] Review evidence of continuous monitoring for AC-10

## How to Test

### Step 1: Review Documentation

Examine the System Security Plan (SSP) and related artifacts for AC-10 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 | Test web application access controls   | `hackbrowser`        |

## Remediation Guide

### Control Statement

Limit the number of concurrent sessions for each [organization-defined] to [organization-defined].

### Implementation Guidance

Organizations may define the maximum number of concurrent sessions for system accounts globally, by account type, by account, or any combination thereof. For example, organizations may limit the number of concurrent sessions for system administrators or other individuals working in particularly sensitive domains or mission-critical applications. Concurrent session control addresses concurrent sessions for system accounts. It does not, however, address concurrent sessions by single users via multiple system accounts.

## Risk Assessment

| Finding                                          | Severity | Impact                    |
| ------------------------------------------------ | -------- | ------------------------- |
| AC-10 Concurrent Session Control not implemented | High     | Access Control            |
| AC-10 partially implemented                      | Medium   | Incomplete Access Control |

## CWE Categories

| CWE ID  | Title                   |
| ------- | ----------------------- |
| CWE-284 | Improper Access Control |

## References

- [NIST SP 800-53 Rev 5 - AC-10](https://csrc.nist.gov/projects/cprt/catalog#/cprt/framework/version/SP_800_53_5_1_1/home?element=ac-10)
- [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 (SC-23) reviewed