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Home The CMMC Guide Part III · System and Communications Protection SC.L2-3.13.2
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SC.L2-3.13.2  Security Engineering Principles

Employ architectural designs, software development techniques, and systems engineering principles that promote effective information security within organizational systems.

Family
System and Communications ProtectionSC, 16 requirements
Point Value
5Highest weight in the methodology
POA&M Eligible
NoCannot remain open at assessment
Objectives
SixPer NIST SP 800-171A

1Overview

SC.L2-3.13.2 requires that security be built into how systems are designed and developed. It requires that the organization employ architectural designs, software development techniques, and systems engineering principles that promote effective information security, so that security is a property of the system's construction rather than something added afterward. It is a five-point requirement that cannot be deferred on a plan of action.

Security bolted onto a finished system is weaker and costlier than security designed in from the start. This control requires that the organization identify architectural designs, software development techniques, and systems engineering principles that promote effective information security, and then actually employ them. It applies to how systems are architected, how software is developed, and how engineering decisions are made, so that security considerations shape the system as it is built. Its five-point weight reflects that a system engineered without security in mind carries weaknesses that are hard to remedy later.

The requirement · NIST SP 800-171 Rev 2, 3.13.2

Employ architectural designs, software development techniques, and systems engineering principles that promote effective information security within organizational systems.

The requirement names three categories, architectural designs, software development techniques, and systems engineering principles, and the six assessment objectives pair identification and employment for each. The organization first identifies, within each category, the practices that promote effective information security, then employs those identified practices. The result is that security-promoting approaches are chosen deliberately and applied in how systems are built and maintained.

2The Assessment Objectives

NIST SP 800-171A decomposes 3.13.2 into six objectives: identify and employ security-promoting practices across three categories.

[a]

Architectural designs that promote effective information security are identified. Security-promoting designs are chosen.

MeetsSecurity-promoting architectural designs are identified.
FailsNo security-promoting designs are identified.
[b]

Software development techniques that promote effective information security are identified. Security-promoting techniques are chosen.

MeetsSecurity-promoting development techniques are identified.
FailsNo security-promoting techniques are identified.
[c]

Systems engineering principles that promote effective information security are identified. Security-promoting principles are chosen.

MeetsSecurity-promoting engineering principles are identified.
FailsNo security-promoting principles are identified.
[d]

Identified architectural designs are employed. The chosen designs are used.

MeetsThe identified architectural designs are employed.
FailsIdentified designs are not actually used.
[e]

Identified software development techniques are employed. The chosen techniques are used.

MeetsThe identified development techniques are employed.
FailsIdentified techniques are not actually used.
[f]

Identified systems engineering principles are employed. The chosen principles are used.

MeetsThe identified engineering principles are employed.
FailsIdentified principles are not actually used.

The six objectives pair identify and employ across the three categories. The common gap is between identification and employment: practices are named in policy but not actually applied in how systems are built. The assessor looks for both identification and employment in all three categories.

3Failure Patterns

The failures are about security-promoting practices named but not applied.

Identified but not employed

Naming security-promoting designs, techniques, or principles without actually using them satisfies identification but not employment. The practices have to shape how systems are built.

Security added after the fact

Building systems without security-promoting engineering and bolting on protection later produces weaker results. Employing these practices during design and development builds security in.

One category only

Addressing architecture while ignoring development techniques or engineering principles, or the reverse, leaves categories unmet. All three have to be identified and employed.

The common root
This control fails when security is treated as a feature to add rather than a property to build in. A system engineered without security-promoting practices carries structural weaknesses that later controls can only patch over, so identifying and employing these practices during design and development is what gives the system a secure foundation.

4Ownership

This is an architecture and engineering-owned control.

RoleResponsibility for this control
System architects and engineersIdentify and employ security-promoting designs, techniques, and principles. Own the engineering evidence.
DevelopersApply the identified security-promoting development techniques.
Security or compliance leadConfirms identification and employment across all three categories.
See also: This control shapes the boundary architecture of SC.L2-3.13.1 and the separation of SC.L2-3.13.3.

5Tooling

The control is largely procedural, delivered by adopted security-promoting engineering practices.

ObjectivesToolingWhat it provides
[a], [d]Secure architecture standardsIdentified and employed security-promoting designs.
[b], [e]Secure development practicesIdentified and employed development techniques.
[c], [f]Systems engineering principlesIdentified and employed engineering principles.

The caveat is that the practices have to be employed, not just documented. A catalog of security-promoting approaches that no project applies satisfies identification but leaves employment unmet. The assessor examines identification and employment across all three categories, so all six objectives have to hold.

6Evidence

The satisfied version of 3.13.2 shows security-promoting practices identified and applied.

EvidenceWhat it demonstrates
Architecture and engineering standardsObjectives [a], [b], [c]. Security-promoting practices identified.
System designs and development recordsObjectives [d], [e], [f]. The practices employed.

The evidence should show security-promoting designs, techniques, and principles identified and then employed in how systems are built. The standards together with the design and development records are the clearest demonstration, and because this control cannot sit on a plan of action, the practices have to be real at the time of assessment.

Security built in beats security bolted on

A system engineered without security-promoting practices carries weaknesses later controls can only patch, so this five-point control asks that such practices be identified and employed across architecture, development, and engineering. Building security into how systems are designed is part of the onsite readiness work this practice does, and it is one of the controls that must be met rather than deferred.

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7Sources

  1. NIST Special Publication 800-171 Rev 2, Protecting Controlled Unclassified Information in Nonfederal Systems and Organizations, requirement 3.13.2. csrc.nist.gov
  2. NIST Special Publication 800-171A, Assessing Security Requirements for Controlled Unclassified Information, assessment objectives 3.13.2[a] through 3.13.2[f]. csrc.nist.gov
  3. 32 CFR 170.24, CMMC Scoring Methodology, listing SC.L2-3.13.2 among the five-point basic security requirements. ecfr.gov
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About the Author
David W. Koran is a CyberAB Registered Practitioner Advanced and the author of The CMMC Decision, now in its second edition. He works onsite with defense contractors and their counsel, from the first leadership briefing through the pre-assessment review. Reach him at 802-335-2662 or dkoran@davidkoran.com.
Entry SC.L2-3.13.2 · Edition 2026.1 · Last reviewed July 12, 2026