Threat Modeling and OWASP Risks

MODULE 16 · LESSON 16.1

Identify assets, actors, trust boundaries and likely abuse before choosing controls.

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Where this fits in CourseFlow

This topic earns its place in CourseFlow by changing something another person can inspect, test or review. This lesson defines an application trust boundary, where an explicit contract is safer than framework convention or an undocumented assumption.

Here, that decision supports a specific checkpoint: Threat-model and harden the CourseFlow application. A reviewable result should include a repeatable request, automated test, query result and failure response rather than a claim that the feature simply works.

Threat Modeling and OWASP Risks workflowA four-step visual showing assets, attack surface, STRIDE questions, risk prioritization.Threat Modeling and OWASP Risks workflow1Assets2Attack Surface3STRIDE Questions4RiskPrioritization

Threat Modeling and OWASP Risks workflow

  1. 1Assets
  2. 2Attack Surface
  3. 3STRIDE Questions
  4. 4Risk Prioritization
Threat Modeling and OWASP Risks workflow: a practical sequence used in this lesson.

A practical model for threat modeling and owasp risks

Identify assets, actors, trust boundaries and likely abuse before choosing controls. The useful unit of understanding is the boundary: who owns the decision, which input crosses it, what result is visible and how a failure is reported.

  • Assets: Name its input, observable result and most likely failure in this lesson.
  • Attack Surface: Locate this responsibility in CourseFlow and defend the boundary you chose.
  • STRIDE Questions: Implement one behavior that another learner can reproduce without reading your mind.
  • Risk Prioritization: Compare the simplest correct approach with one credible alternative.

Read the result, not just the syntax

Start by locating assets in the sample. Then trace what reaches attack surface and what the caller receives back.

TEXT
Asset: learner account
Boundary: browser -> API
Threat: stolen session
Controls: HTTPS, HttpOnly cookie, rotation, revocation
Make one assumption explicit

Write down what the sample assumes about assets. Break that assumption deliberately and inspect the response.

Build the smallest useful version

  1. 1
    Assets

    Break one assumption on purpose, make recovery clear and record the trade-off you accepted.

  2. 2
    Attack Surface

    Name the caller and the owner of this behavior before changing the implementation.

  3. 3
    STRIDE Questions

    Compare expected and actual output before editing; the difference tells you where to investigate.

  4. 4
    Risk Prioritization

    Keep names tied to the product rule so a reviewer can follow the change without decoding abbreviations.

Failure patterns to recognize

  • Treating assets as vocabulary instead of defining the behavior it must produce.
  • Testing the expected path while ignoring an empty, invalid, repeated or unauthorized case around attack surface.
  • Allowing STRIDE questions to cross a boundary without an explicit contract or useful error.
  • Changing several layers before capturing the first piece of evidence, which makes the original cause harder to see.

A debugging route that preserves evidence

  1. Reduce the problem to the smallest failing Threat Modeling and OWASP Risks case.
  2. Capture the actual input and output at the assets boundary.
  3. Read the first relevant error, request, trace or query rather than the loudest downstream symptom.
  4. Test one explanation for the failure in attack surface; avoid changing two variables together.
  5. Keep a regression check that would expose the same defect if it returned.

Security decision

Validate external input, authorize the requested action, use parameterized data access, and keep credentials out of responses, source control and logs.

Performance decision

Bound queries and collections, inspect the actual request or query plan, and optimize only the slow boundary confirmed by evidence.

PRACTICE

Build something you can inspect

Create a lightweight threat model for login, file upload and enrollment flows.

Stretch challenge

Add observability for attack surface without leaking personal data, secrets or noisy implementation details.

Definition of done

  • The behavior around assets works with realistic input.
  • A failure involving attack surface is handled clearly and without leaking sensitive detail.
  • The implementation remains keyboard-usable when it produces an interface.
  • Your evidence directly supports the claim made in the exercise.
  • The README records the important trade-off without pretending the solution is universal.

Check your reasoning

Why should risk combine likelihood and impact rather than only technical severity?

Answer by naming the expected assets behavior, the layer responsible for it and the evidence that would confirm your explanation.

Where would you investigate the first failure?

Start where attack surface crosses a boundary. Compare the actual input and output there before following downstream symptoms.

What would make this work reviewable?

Show the focused change, repeatable steps, the result of your check and one honest trade-off connected to STRIDE questions.

What to carry into the next lesson

  • Identify assets, actors, trust boundaries and likely abuse before choosing controls.
  • Keep assets visible at the boundary where it can be tested.
  • Use evidence from attack surface before widening the implementation.

References and related reading

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