Architecture and design validation

Tools that test design decisions for adhering to some basic security policies do not exist (yet) because there are no hard rules or silver bullets regarding what security concerns should be considered for a particular application, but some general secure design principles can help (and some of these are trade-offs with one or some of the other principles):

• Minimise attack surface – Reduce the number and size of entry points that can be exploited by adversaries as much as possible

• Principle of least privilege – Give just enough access level to do a job

• Separate duties – Different entities have different roles

• Defence in depth – Multiple layers of control make it harder to exploit a system

• Fail secure – Limit the amount of information that is exposed when a system encounters errors

• Economy of mechanisms – Keep things as simple as possible

• Complete mediation – Validate all access to all resources of a system, always

• Open design – Use proven open standards

• Psychological acceptability – Protect a system but do not hamper users of the system

• Weakest link – Any system is only as strong as its weakest link

• Single point of failure – Add redundancy to critical systems