Trust Boundaries Mapping

Defining zones of varying trust in an application helps identify vulnerable areas of communication and possible attack paths for security violations. Certain components of a system have trust relationships (sometimes implicit, sometime explicit) with other parts of the system. Some of these trust relationships offer ”trust elevation” possibilities—that is, these components can escalate trust privileges of a user when data or control flow cross internal boundaries from a region of less trust to a region of more. For systems that have n-tier architecture or that rely on several third-party components, the potential for missing trust validation checks is high, so drawing trust boundaries becomes critical for such systems. Drawing clear boundaries of trust on component interactions and identifying data validation points (or chokepoints) helps in validating those chokepoints and testing some of the design assumptions behind trust relationships. Combining trust zone mapping with data-flow analysis helps identify data that move from one trust zone to another and whether data checkpoints are sufficient to prevent trust elevation possibilities. This insight can be used to create effective test cases.