Decomposing the Applications – A Threat Modeling View (Good from Application Risk visibility perspective too)

Step 1: Identification of trust boundaries

A trust boundary is the point at which the trust level or privilege changes.

Like Trust boundaries exist between the external (Internet) and the DMZ and between the DMZ

And the internal (Intranet) zones.

Step 2: Identification of Data/Information Entry Points

Entry points are those points from where user inputs comes in. Each entry point can be a potential threat source and so must be explicitly identified and safeguarded.

Entry points in a Web application could include any page that takes in user input. Like log on page etc.

Step 3: Identification of Data/Information Exit Points

Exit points are those points that display information from within the system. It also includes processes that take data out of the system.

Exit points can be the source of information leakage and need to be secured. Like Search Result page, backup process etc.

Step 4: Identification of Data/Information Flows

Data flow diagram or sequence diagram help to understand how the application accept, process, handle and transfer the data flowing across the different trust boundaries

Step 5: Identification of Privileged code/passes

Code or passes that allows elevation of privilege or the execution of privileged operations is identified. All administrator functions are identified

Step 6: Documenting the security Profile of Application

This involves identification of the design and implementation mechanisms that impact the security of the application. The Security profile which we should consider are : Confidentiality, Integrity, Availability, Authentication, Authorization etc. against Design/implementation consideration