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Security · Version 1.3.0 · Reviewed 2026-08-02

WebAuthn & Passkey Advisor

Find and prioritize exploitable risk in passkey flow design and credential recovery with evidence, explicit trade-offs, and a verification plan.

4 method steps 4 documented failure modes 4 diagnostic checks 7 quality gates

Designs passkey registration and authentication with relying-party IDs, origins, attestation, discoverable credentials, recovery, and sync considerations.

₹199 one-time

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What this skill helps you do

  • Passkey flow design
  • Credential recovery
  • WebAuthn verification review

How WebAuthn & Passkey Advisor works

You provide

Code, configuration, and the deployment trust model

It inspects

Reachable input-to-sink paths for passkey flow design

It decides

A credential recovery finding ranked by blast radius

You verify

Re-attempt the exploit path after remediation

What it checks first

WebAuthn & Passkey Advisor designs passkey registration and authentication with relying-party IDs, origins, attestation, discoverable credentials, recovery, and sync considerations. Use it when the work involves Passkey flow design, Credential recovery, WebAuthn verification review.

  1. Trust boundaries and every point where untrusted input crosses one.
  2. Where authorization is enforced relative to where data is accessed.
  3. Secret handling: creation, storage, transmission, rotation, and revocation.
  4. What an attacker gains at each step, which determines whether a finding is material.

Failure modes it recognizes

  • Authorization enforced at the perimeter while internal callers reach the same data unchecked.
  • A single unparameterized query path among many parameterized ones.
  • Sensitive values written to logs or error responses.
  • A dependency vulnerability that is reachable in one code path and unreachable in the rest.

Answers it will reject

  • Reporting theoretical findings as exploitable without a demonstrated path.
  • Blocking a payload signature instead of removing the vulnerability class.
  • Treating obscurity as a control, which delays discovery without preventing exploitation.

Decision rules it applies

  • Prioritize by reachability and blast radius, not by scanner severity.
  • Fail closed on any ambiguity in an access decision.
  • Prefer eliminating the capability over sanitizing input into it.

Evidence it asks for

  • Trace input to sink and name every file and function on the path.
  • Verify the fix by attempting the original exploit path.
  • Check logs for prior exploitation before closing a finding.

The method inside

  1. Map the artifact, actors, boundaries, and invariants relevant to passkey flow design.
  2. Trace concrete failure or abuse paths for credential recovery; do not report checklist items without a mechanism.
  3. Prioritize WebAuthn verification review findings by impact, likelihood, confidence, and cost of correction.
  4. Recommend the smallest defensible change, then define how an independent reviewer can verify it.

Deliverables

  • Passkey flow design assessment
  • Credential recovery decision and action plan
  • WebAuthn verification review verification checklist

Evidence requirements

  • Code, configuration, data flows, and trust boundaries
  • Identity, authorization, and deployment context
  • Threat model, controls, and known assumptions

Quality gates

  • Every material claim traces to supplied evidence or is labeled as a hypothesis.
  • The response follows the declared deliverable contract.
  • No execution, access, measurement, or verification is invented.
  • Secrets and personal data are redacted rather than repeated.
  • The user receives a concrete independent verification step.
  • The relevant failure modes in this domain were considered rather than only the reported symptom.
  • No listed anti-pattern was recommended as a solution.

Example task

Input

Add passkeys to our multi-domain product without locking users out when they change devices.

Expected output

Choose the registrable parent as RP ID only if every approved origin is under it, support discoverable credentials, and design account recovery independently because passkey synchronization varies by ecosystem...

Boundaries and compatibility

Ideal for

  • Passkey flow design: produce a decision or artifact grounded in supplied evidence.
  • Credential recovery: produce a decision or artifact grounded in supplied evidence.
  • WebAuthn verification review: produce a decision or artifact grounded in supplied evidence.

Out of scope

  • Authorizing offensive actions against systems without permission
  • Reporting theoretical issues as exploitable without a path

Agent compatibility

  • GitHub Copilot Agent Skills
  • Cursor Agent Skills
  • Claude Code Skills
  • OpenAI Codex Skills
  • JetBrains Junie Skills

Tool policy: Advisory by default. No tools are assumed. If the host provides tools, use read-only evidence gathering unless the user explicitly approves a scoped write or execution action.