Trike is a unified conceptual framework for security auditing from a risk management perspective through the generation of threat models in a reliable, repeatable manner. A security auditing team can use it to completely and accurately describe the security characteristics of a system from its high-level architecture to its low-level implementation details. Trike also enables communication among security team members and between security teams and other stakeholders by providing a consistent conceptual framework. This document describes the current version of the methodology (currently under heavy development) in sufficient detail to allow its use. In addition to detail on the threat model itself (including automatic threat generation and attack graphs), we cover the two models used in its generation, namely the requirements model and the implementation model, along with notes on risk analysis and work flows. The final version of this paper will include a fully worked example for the entire process. Trike is distinguished from other threat modeling methodologies by the high levels of automation possible within the system, the defensive perspective of the system, and the degree of formalism present in the methodology. Portions of this methodology are currently experimental; as they have not been fully tested against real systems, care should be exercised when using them.

The methodology described in this document is copyright 2003-2005 Eleanor Saitta, Brenda Larcom, and Michael Eddington, excluding those covered under other copyrights, and the whole may be used under the MIT license, .software. being replaced with .methodology. throughout. This document is published under the Creative Commons attribution-noncommercial-sharealike 2.0 license.