16.10: Apply Secure Design Principles in Application Architectures
=========================================================
Apply secure design principles in application architectures. Secure design principles include the concept of least privilege and enforcing mediation to validate every operation that the user makes, promoting the concept of "never trust user input." Examples include ensuring that explicit error checking is performed and documented for all input, including for size, data type, and acceptable ranges or formats. Secure design also means minimizing the application infrastructure attack surface, such as turning off unprotected ports and services, removing unnecessary programs and files, and renaming or removing default accounts.

.. list-table::
	:header-rows: 1

	* - Asset Type
	  - Security Function
	  - Implementation Groups
	* - Applications
	  - Protect
	  - 2, 3

Dependencies
------------
* Safeguard 16.1: Establish and Maintain a Secure Application Development Process

Inputs
-----------
#. :code:`GV49`: Secure Application Development Process
#. :code:`GV50`: Application Infrastructure Components

Operations
----------
#. Use Input 1 :code:`GV49` to determine whether the process outlines a secure software framework that includes secure design principles
	#. If the framework exists, M1 = 1
	#. If the framework does not exist, M1 = 0
#. For each application infrastructure component in Input 2 :code:`GV50`, determine whether the secure design principles were applied per the framework
	#. Identify and enumerate application infrastructure components where design principles are applied (M3)
	#. Identify and enumerate application infrastructure components where design principles are not applied (M4)

Measures
--------
* M1 = Output of Operation 1
* M2 = Count of Input 2 :code:`GV50`
* M3 = Count of applications infrastructure components with design principles applied
* M4 = Count of applications infrastructure components without design principles applied

Metrics
-------
* If M1 is 0, this safeguard receives a failing score. The other metrics don't apply.

Compliance
^^^^^^^^^
.. list-table::

	* - **Metric**
	  - | The percentage of applications infrastructure components where 
	  - | design principles were applied
	* - **Calculation**
	  - :code:`M3 / M2`


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