OWASP Threat Dragon

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OWASP Threat Dragon Project

An online threat modelling web application including system diagramming and a rule engine to auto-generate threats/mitigations. The focus will be on great UX a powerful rule engine and alignment with other development lifecycle tools.


Threat modelling is widely regarded as a powerful way to build security into the design of applications early in the development lifecycle. At its best, it is especially good for

  • Ensuring defence-in-depth
  • Establishing consistent security design patterns across an application
  • Flushing out security requirements and user stories

However, effective adoption by organisations can be difficult. Reasons for this include:

  • There are no cross-platform, free tools (that I am aware of)
  • The usability of existing tools is not great - productivity for the team is therefore poor, especially in the early stages of adoption
  • The learning curve for teams is steep - threat modelling often ends up being left to a small "expert" subset of a team and ignores the perspectives from the wider team
  • Integration with other development lifecycle tools (e.g. issue tracking tools) is poor - leading to models being ignored

OWASP Threat Dragon intends to address this by providing a free, open-source, cross-platform threat modelling tool for teams implementing the STRIDE approach. The key areas of focus for the tool will be to provide:

  • Great UX - using Threat Dragon should be simple, engaging and fun
  • A powerful threat/mitigation rule engine - this will lower the barrier to entry for teams and allow non-specialists to contribute
  • Integration points with other development lifecycle tools - this will ensure that models slot nicely into the development lifecycle and can remain relevant as the project evolves


This program is free software: you can redistribute it and/or modify it under the terms of the Apache 2.0 License

Project Resources

The source code for the project can be found here:


And you can click here to see a working prototype.

Project Leader

Mike Goodwin

Related Projects


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Incubator Project Owasp-builders-small.png

News and Events


Mike Goodwin


Vision for the project:


The overall vision for the project is to implement a tool that removes as many barriers as possible for organisations wanting to embed threat modelling into their development lifecycle. Barriers I have seen are:

- Lack of cross platform tooling: Tool needs to be x-platform
- Poor UX in existing tools, productivity is poor: Great UX is a must
- Steep learning curve for adopting teams: Tool to build in expert knowledge to help the team get started
- Models are ignored: Integration with other lifecycle tools is key

Initial high level plan:


Milestone 1: Alpha release - Basic threat modelling experience

- Architecture review of the existing prototype with refinement/change where required
- Secure design review and implementation of findings
- Development of tests (unit and manual)
- Draft end user documentation
- "Publicity drive" to sign up alpha/beta users and generate feedback

Milestone 2: Beta release - Threat/mitigation rule engine

- Refinement of UX based on feedback from the alpha release
- (Some) feature enhancements based on feedback from the alpha release
- Implementation of a rule engine for generation of threats/mitigations
- Updated tests and end-user documentation

Milestone 3: Release 1

- Key refinements, bug fixes and new features based on feedback from the beta release
- Complete end user documentation
- Penetration test

Milestone 4 - Dev lifecycle integration

 - Detailed scope to be defined, but in general the vision is to support hooks into issue tracking and requirements management tool so that threats/mitigations can be tracked through to implementation and test


This is hard to estimate as it could change a lot if there were other developers involved. Based on my current velocity with just me, I would say release 1 could be complete in 1 year (optimistically).



The technical architecture is javascript from top to bottom. In the client the key libraries are Angular for the MVC architecture and JointJS for the diagraming. JointJS has a log of great features, but is not a perfect fit for Angular. This needs a review. In the prototype, all storage is done on the client using browser local storage.

There is nothing on the server side at the moment in the prototype. Areas where this might become necessary are

- If the threat rule engine requires too much power to run feasibly on the client
- Supporting hooks in to other dev lifecycle tools

If needed I plan to use node.js on the server so that the rule engine can be flexible enough to run either client or server side.

Server-side storage has not been needed yet. If it becomes necessary, then a review of options will be needed to find a way to do this that is sustainable and consistent with the open source approach for the project.



- Getting enough usage of the alpha and beta to get the UX and rule engine right
- Finding a sustainable way to host it, especially if it needs any kind of server side storage or processing - the prototype today just serves static content and all the logic is on the client side

Getting Involved


1) Application source code for a threat modeling tool

2) End user documentation for the tool

3) An online hosted version of the tool