Clearing The Confusion
Government contractors preparing for Cybersecurity Maturity Model Certification (CMMC) Level 2 often encounter the term mobile code and assume it refers to phones or tablets. This interpretation is understandable but inaccurate. The requirement is not about mobile device management. Instead, it addresses software that moves across a network and executes automatically on a system, often inside a browser or embedded application.
Mobile code is present throughout common business workflows. If uncontrolled, it creates risk for systems that handle Controlled Unclassified Information (CUI). This article explains what mobile code is, why it matters for the Defense Industrial Base, and how to implement and document the controls that CMMC 3.13.13 expects. The goal is to replace uncertainty with clear direction and help your organization meet compliance expectations confidently.
If you are still developing your overall strategy, MAD Security’s CMMC Compliance resource provides a broader overview of requirements, timelines, and how to get started.
What Mobile Code Is And Is Not
Mobile code is critical for many business applications. It is also a method threat actors use to gain unauthorized access or escalate privileges. Attackers target mobile code because it runs automatically and can circumvent traditional protections if not properly governed.
Common methods include:
| JavaScript | |
| Flash | |
| ActiveX controls | |
| Java applets | |
| Java applets |
These technologies load automatically when users access webpages, open interactive documents, or work in browser-based tools. They are essential for modern applications but can introduce risk when the code is untrusted or unexpected.
A critical distinction is that mobile code has no connection to mobile devices. The term refers to the mobility of the code, not the hardware. Organizations that focus on phones and tablets miss the browser scripting and embedded technologies that CMMC 3.13.13 is actually targeting.
If your organization uses cloud applications, online portals, PDF readers, or interactive forms, you already use mobile code. Identifying where and how it runs is the first step toward applying compliant controls.
Why Mobile Code Matters In The Defense Industrial Base
Mobile code is critical for many business applications. It is also a method threat actors use to gain unauthorized access or escalate privileges. Attackers target mobile code because it runs automatically and can circumvent traditional protections if not properly governed.
Common methods include:
| Drive-by downloads triggered through browser scripts | |
| Script-based privilege escalation | |
| Bypassing endpoint controls | |
| Delivering additional malicious components |
These risks carry added significance in the Defense Industrial Base. Systems that store or process CUI attract advanced threat actors that actively seek exploitable paths. Any technology that enables unauthorized script execution increases the likelihood of a breach.
From a compliance standpoint, unmanaged mobile code is frequently identified as a gap during NIST 800-171 assessments and will be reviewed closely under CMMC Level 2. The requirement exists to ensure contractors understand the behavior of dynamic code in their environment and maintain oversight of how it executes.
Breaking Down CMMC 3.13.13
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CMMC 3.13.13 requires organizations to control and monitor mobile code. The wording may appear broad, but the expectations are clear. Contractors must establish which types of mobile code are acceptable, enforce those decisions, and maintain visibility into how they operate.
A practical interpretation includes:
| Identify the types of mobile code used | |
| Restrict or allow specific types based on business need | |
| Monitor how mobile code executes across systems | |
| Document the policies and technical controls that enforce restrictions |
CMMC 3.13.13 aligns with NIST 800-171 control 3.13.13. Both emphasize deliberate management of dynamic, network-delivered code rather than reliance on general-purpose security tools.
A straightforward summary of the requirement is:
| Control | Monitor | Document | Review |
Assessors will look for evidence that your organization understands its mobile code footprint, applies restrictions consistently, and monitors execution effectively. They will focus on script controls, browser configuration, and documented processes, not mobile device management.
Common Pitfalls And Misunderstandings
Organizations often struggle with this requirement for predictable reasons. Many stems from terminology confusion or assumptions about what existing tools can provide.
Common mistakes include:
| Interpreting the control as a mobile device requirement | |
| Overlooking browser-based scripts such as JavaScript | |
| Assuming antivirus or firewalls meet the requirement | |
| Omitting mobile code controls from the System Security Plan (SSP) | |
| Relying on user training instead of technical enforcement |
How To Control And Monitor Mobile Code (Technically)
Most organizations already have the tools needed to address this requirement. The key is configuring them intentionally and ensuring enforcement aligns with documented policy.
Effective technical controls include:
| Browser security configurations to restrict or disable scripts and plug-ins | |
| Group Policy Objects (GPOs) to manage ActiveX, Flash, and other script engines | |
| Endpoint Detection and Response (EDR) for script blocking and behavioral controls | |
| Application whitelisting or sandboxing to regulate execution | |
| Web filtering solutions to prevent access to sites requiring unapproved mobile code types |
| Logging whenever mobile code runs or is blocked | |
| Alerts for unauthorized or abnormal execution | |
| Regular review of activity to identify anomalies |
These controls demonstrate that your organization is applying the “control” and “monitor” aspects of the requirement. They also provide evidence needed during assessments to show consistent enforcement.
What To Include In Your SSP
Your SSP is the primary reference for assessors. It must clearly outline how your organization defines, controls, and monitors mobile code.
Your SSP should include:
| Allowed and disallowed types of mobile code | |
| Locations or contexts where mobile code is permitted | |
| Technical controls used to enforce restrictions | |
| Monitoring and review processes | |
| References to supporting policies such as mobile code or acceptable use policies |
Final Thoughts: Build Confidence Through Clarity and Controls
Mobile code often feels abstract until organizations recognize how frequently it runs in their systems. Once identified, the path to meeting CMMC 3.13.13 becomes manageable. Effective controls rely on a combination of technical enforcement, monitoring, and accurate documentation.
A thoughtful approach strengthens security, supports successful assessments, and helps maintain a reliable environment for handling CUI.
Partner with MAD Security for CMMC Readiness
MAD Security supports government contractors that handle CUI by simplifying cybersecurity and compliance. As a CMMC Registered Provider Organization with deep expertise in NIST frameworks, DFARS requirements, and security operations, MAD Security helps organizations identify mobile code usage, deploy effective controls, and prepare documentation that aligns with assessment expectations. Our team stands ready to guide your organization toward CMMC Level 2 with clarity, precision, and commitment to high standards.
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Original Publish Date: TO BE FINALIZED
By: MAD Security
