SA 15(5) Attack Surface Reduction

---
name: "SA-15(5)_attack-surface-reduction"
description: "Require the developer of the system, system component, or system service to reduce attack surfaces to [organization-defined]."
category: "configuration"
version: "5.2.0"
author: "cyberstrike-official"
tags:
  - nist
  - sp800-53
  - rev5
  - sa-15-5
  - sa
  - enhancement
tech_stack:
  - any
cwe_ids:
  - CWE-16
chains_with:
  - AC-6
  - CM-7
  - RA-3
  - SA-11
prerequisites:
  - SA-15
severity_boost:
  AC-6: "Chain with AC-6 for comprehensive security coverage"
  CM-7: "Chain with CM-7 for comprehensive security coverage"
  RA-3: "Chain with RA-3 for comprehensive security coverage"
---

# SA-15(5) Attack Surface Reduction

> **Enhancement of:** SA-15

## High-Level Description

**Family:** System and Services Acquisition (SA)
**Framework:** NIST SP 800-53 Rev 5

Attack surface reduction is closely aligned with threat and vulnerability analyses and system architecture and design. Attack surface reduction is a means of reducing risk to organizations by giving attackers less opportunity to exploit weaknesses or deficiencies (i.e., potential vulnerabilities) within systems, system components, and system services. Attack surface reduction includes implementing the concept of layered defenses, applying the principles of least privilege and least functionality, applying secure software development practices, deprecating unsafe functions, reducing entry points available to unauthorized users, reducing the amount of code that executes, and eliminating application programming interfaces (APIs) that are vulnerable to attacks.

## What to Check

- [ ] Verify SA-15(5) Attack Surface Reduction is documented in SSP
- [ ] Confirm control is operating effectively
- [ ] Review evidence of continuous monitoring for SA-15(5)
- [ ] Verify enhancement builds upon base control SA-15

## How to Test

### Step 1: Review Documentation

Examine the System Security Plan (SSP) and related artifacts for SA-15(5) 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 |
| ------------- | --------------------------------- | ----- |
| Manual Review | Documentation and interview-based | N/A   |

## Remediation Guide

### Control Statement

Require the developer of the system, system component, or system service to reduce attack surfaces to [organization-defined].

### Implementation Guidance

Attack surface reduction is closely aligned with threat and vulnerability analyses and system architecture and design. Attack surface reduction is a means of reducing risk to organizations by giving attackers less opportunity to exploit weaknesses or deficiencies (i.e., potential vulnerabilities) within systems, system components, and system services. Attack surface reduction includes implementing the concept of layered defenses, applying the principles of least privilege and least functionality, applying secure software development practices, deprecating unsafe functions, reducing entry points available to unauthorized users, reducing the amount of code that executes, and eliminating application programming interfaces (APIs) that are vulnerable to attacks.

## Risk Assessment

| Finding                                           | Severity | Impact                                     |
| ------------------------------------------------- | -------- | ------------------------------------------ |
| SA-15(5) Attack Surface Reduction not implemented | Medium   | System and Services Acquisition            |
| SA-15(5) partially implemented                    | Low      | Incomplete System and Services Acquisition |

## CWE Categories

| CWE ID | Title         |
| ------ | ------------- |
| CWE-16 | Configuration |

## References

- [NIST SP 800-53 Rev 5 - SA-15(5)](https://csrc.nist.gov/projects/cprt/catalog#/cprt/framework/version/SP_800_53_5_1_1/home?element=sa-15.5)
- [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 (AC-6, CM-7, RA-3, SA-11) reviewed