Threat Modeling as Code (Python)

A declarative, code-first threat-modeling library for Python. Express your system as components, trust boundaries, and data flows, then analyze it with the STRIDE methodology to get actionable, version-controlled mitigations.

Features

• Declarative Model, Component, Boundary, and DataFlow types
• STRIDE threat classification:
  • Spoofing
  • Tampering
  • Repudiation
  • Information Disclosure
  • Denial of Service
  • Elevation of Privilege
• Trust-boundary-aware data flow analysis
• Built-in, context-aware mitigation catalog
• Zero runtime dependencies
• Type hints included (py.typed)
• Supports Python 3.8+

Installation

pip install threat-modeling-py

Quick Start

from threat_modeling import Model, Component, Boundary, DataFlow

app = Model('payment-api')
app.add(Component('api', component_type='api', environment='k8s',
                  stores=['user-data'], exposed=True))
app.add(Boundary('internet', untrusted=True, trusts=['api']))
app.add(DataFlow('request', 'browser', 'api', protocol='https',
                 auth='bearer', data_types=['payment-card']))

for threat in app.analyze():
    print(threat.kind, '-', threat.target)
    for mitigation in threat.mitigations:
        print('  -', mitigation)

Core Concepts

• Model — the top-level container for components, boundaries, and data flows.
• Component — a service, API, database, browser, or any architectural element.
• Boundary — a trust boundary; untrusted=True marks external zones such as the internet.
• DataFlow — a directed interaction between two components.
• Threat — a STRIDE finding with a target, description, and list of mitigations.

Why Threat Modeling as Code?

• Version control: threat models live in the same repo as the architecture.
• Automation: run analyze() in CI to catch changes in risk posture.
• Consistency: use the same model across languages and teams.

Cross-Language Support

This library is also available for Go, TypeScript, and Rust.

Development

cd implementations/security/threat-modeling/python
pip install -e ".[dev]"
pytest test_threat_modeling.py -v

License

MIT License