NIST 800-53 REV 5 • ACCESS CONTROL
AC-4(24) — Internal Normalized Format
When transferring information between different security domains, parse incoming data into an internal normalized format and regenerate the data to be consistent with its intended specification.
CMMC Practice Mapping
No direct CMMC mapping
NIST 800-171 Mapping
No direct NIST 800-171 mapping
Related Controls
No related controls listed
Supplemental Guidance
Converting data into normalized forms is one of most of effective mechanisms to stop malicious attacks and large classes of data exfiltration.
Practitioner Notes
Data should be converted to an internal normalized format before content inspection, then converted back for delivery. This prevents attackers from using encoding tricks to sneak data past your filters.
Example 1: Configure your web application firewall to normalize all input before inspection — decode URL encoding, HTML entities, and Unicode escapes. In ModSecurity, enable the t:urlDecode,t:htmlEntityDecode,t:utf8toUnicode transformation chain so that encoded attack payloads are detected.
Example 2: On your email gateway, configure the content filter to decode Base64 attachments and inspect the actual content rather than just the encoded blob. This catches attackers who Base64-encode malicious payloads to bypass simple pattern matching.