SI-10(5)_restrict-inputs-to-trusted-sources-and-approved-formats

SI-10(5) Restrict Inputs to Trusted Sources and Approved Formats

Enhancement of: SI-10

High-Level Description

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

Restricting the use of inputs to trusted sources and in trusted formats applies the concept of authorized or permitted software to information inputs. Specifying known trusted sources for information inputs and acceptable formats for such inputs can reduce the probability of malicious activity. The information inputs are those defined by the organization in the base control ( SI-10).

What to Check

• Verify SI-10(5) Restrict Inputs to Trusted Sources and Approved Formats is documented in SSP
• Confirm control is operating effectively
• Review evidence of continuous monitoring for SI-10(5)
• Verify enhancement builds upon base control SI-10

How to Test

Step 1: Review Documentation

Examine the System Security Plan (SSP) and related artifacts for SI-10(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

Remediation Guide

Control Statement

Restrict the use of information inputs to [organization-defined] and/or [organization-defined].

Implementation Guidance

Restricting the use of inputs to trusted sources and in trusted formats applies the concept of authorized or permitted software to information inputs. Specifying known trusted sources for information inputs and acceptable formats for such inputs can reduce the probability of malicious activity. The information inputs are those defined by the organization in the base control ( SI-10).

Risk Assessment

CWE Categories

References

• NIST SP 800-53 Rev 5 - SI-10(5)
• NIST SP 800-53A Rev 5 (Assessment Procedures)
• NIST SP 800-53 Rev 5 Full Catalog

Checklist

• Control documented in SSP
• Implementation evidence collected
• Operating effectiveness validated
• Continuous monitoring in place
• Related controls (AC-3, AC-6) reviewed