Dynamic macros are application or scripting macros that change their behaviour or inserted values at run time. They usually use variables, conditions, or context from the host application, so one macro can produce different output for different inputs or users.
How Dynamic Macros Work
Dynamic macros are not fixed text snippets. They evaluate inputs at runtime, then expand into different output depending on variables, conditions, or state from the host application. That makes them useful when the same macro must adapt to different users, records, or workflow contexts.
The key property is that the inserted content is computed, not merely substituted. A dynamic macro can branch, concatenate, look up values, or alter its output based on context that exists only when the page, document, or script is rendered. That flexibility is why they are more powerful, and more unpredictable, than static macros.
Where Dynamic Macros Fit in Application Design
Dynamic macros usually sit between user input and rendered output. They may appear in templates, content editors, automation scripts, or product extensions where developers want reusable logic without hardcoding every variant. In practice, they behave like small runtime decision points embedded in a larger application.
Because they depend on live context, dynamic macros often inherit the trust model of the host system. If the application supplies user attributes, document fields, session state, or environment variables, those inputs can influence what the macro emits. That means the macro is part of the application’s execution path, not just a formatting convenience.
Why Dynamic Macros Matter for Security
Dynamic macros can widen the impact of weak input handling, excessive permissions, or unsafe template design. If a macro can read sensitive context or insert privileged content, a flaw in the macro logic may expose data, alter workflows, or produce output a user should not see.
They also blur the line between content and code. When macro syntax allows nested expressions, conditional execution, or references to host objects, the macro layer can become an attack surface for injection, logic abuse, or unintended disclosure. Security teams should treat macro expansion as an evaluated operation, not just a display function.
Operational Characteristics and Common Use Cases
Dynamic macros are often used to reduce repetition and improve maintainability. One macro can generate personalised text, conditional instructions, report fragments, or workflow labels for many different situations. That makes them attractive in collaboration platforms, document systems, and automation tooling.
The trade-off is complexity. The more the output depends on hidden context, the harder it becomes to reason about what the macro will produce in every environment. Test coverage, review discipline, and clear ownership matter because the same macro can behave differently across users, permissions, or runtime states.
Risk and Threat Considerations
Dynamic macros create risk when runtime inputs are not tightly governed, because the same macro can reveal different content, execute different branches, or inherit privileges from the host application. That makes them a useful vehicle for logic abuse, unintended disclosure, and injection-style failures when templates or script contexts are insufficiently controlled.
Failure mechanism: An attacker or careless editor can influence macro inputs, conditions, or referenced context so the macro expands into unsafe output, leaks sensitive values, or executes a privileged path that was never intended for that audience.
Impact: The result can be data exposure, workflow manipulation, broken authorisation assumptions, or trust in output that no longer reflects the intended policy or audience.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
OWASP ASVS, CIS Controls v8, NIST SP 800-53 Rev 5 and NIST CSF 2.0 set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| OWASP ASVS | V1 — Encoding and Sanitization | Dynamic macros can emit context-driven output that must be encoded and sanitized safely. |
| V15 — Secure Coding and Architecture | Macro logic is runtime application behavior and should be designed to avoid unsafe evaluation paths. | |
| Recommendation — Apply V1 controls to sanitize macro inputs and encode rendered output before display. Design dynamic macro execution to avoid unsafe code-like behavior and hidden trust in context. | ||
| CIS Controls v8 | CIS-16 — Application Software Security | Dynamic macros are an application-layer construct that benefits from secure design, review, and testing controls. |
| Recommendation — Review macro implementations as application code and test them for unsafe branching or disclosure. | ||
| NIST SP 800-53 Rev 5 | SI-10 — Information Input Validation | Macro expansion depends on runtime inputs that must be validated before they influence output. |
| Recommendation — Validate macro inputs and referenced context before allowing them to shape rendered results. | ||
| NIST CSF 2.0 | PR.DS-01 — Data-at-Rest Is Protected | When macros can surface sensitive context, protection of underlying data remains central to safe use. |
| Recommendation — Protect the data sources that macros can reference so sensitive values are not exposed in output. | ||
Practitioner Guidance
Why practitioners should care: Dynamic macros need explicit review because they combine content logic with runtime context, which makes security defects harder to spot than in static templates. Treat them as application logic with security implications, not as harmless formatting helpers.
What to watch for: Pay special attention to macros that read session data, user attributes, hidden fields, environment variables, or privileged document state. Those are the places where a small logic mistake can become a broad disclosure or privilege problem.