Build a threat model for a target codebase. Three modes: "interview" walks an application owner through the four-question framework and produces a threat model from their answers; "bootstrap" derives a threat model from the code plus past vulnerabilities (CVEs, git history, pentest reports) when no

threat model A threat model answers "what could go wrong with this system, who would do it, and what should we do about it?" independently of whether any specific bug has been found yet. It is the map; vulnerability discovery is the metal detector. A good threat model tells the pipeline where to look and tells triage which findings matter. Litmus test: If patching one line of code makes an entry disappear, it was a vulnerability, not a threat. A threat ("attacker achieves RCE via untrusted media parsing") still stands after every known bug is fixed; a vulnerability (" dr wav.h:412 doesn't bounds check chunk size ") does not. This skill produces threats. Vulnerabilities appear only as evidence that raises a threat's likelihood score. Invocation: /threat model [bootstrap then interview bootstrap interview] <target dir [flags] Step 0 — Safety preamble (always runs first) This skill performs static analysis only . It reads source, git history, and any vulnerability reports the user supplies, and writes a single output file ( <target dir /THREAT MODEL.md ). It does not build, execute, fuzz, or modify the target, and does not make network requests against the target's infrastructure. Before proceeding, confirm and state in your first response: 1. The target directory exists and is a local checkout you can read. 2. You will not execute any code from the target directory. 3. If vulns points at a URL or you are asked to "fetch CVEs", you will query only public advisory databases (NVD, GitHub Security Advisories, the project's own issue tracker) and never the target's live deployment. If the user asks you to validate a threat by running an exploit, decline and point them at the vuln pipeline (README Step 2) instead. Step 1 — Route to a mode Parse $ARGUMENTS : First token Route to interview Read interview.md in this directory and follow it. bootstrap Read bootstrap.md in this directory and follow it. bootstrap then interview Bootstrap first, then interview seeded from the draft. See below. anything else, or empty Ask the user: "Is someone who owns or built this system available to answer questions in this session?" Yes and the codebase is checked out → recommend bootstrap then interview . Yes but no codebase → interview.md . No → bootstrap.md . All modes write the same artifact ( THREAT MODEL.md , schema in schema.md ) so downstream consumers (pipeline recon / judge , verifier agents) do not need to know which mode produced it. interview bootstrap Needs An application owner present in the session A local checkout; optionally past vulns Method Four question framework: conversational walk through what are we working on → what can go wrong → what are we going to do about it → did we do a good job Five stages: parallel research swarm → synthesize sections 1 3 + vuln table → generalize vulns into threat classes → STRIDE gap fill → emit Best for New systems, design reviews, systems where the risk lives in business logic the code doesn't show Inherited systems, third party code, OSS dependencies, anything with a CVE history Provenance tag interview bootstrap Context durability. Interview mode is multi turn; tool results from early reads may be evicted before you need them. To stay resilient: Do not read interview.md or bootstrap.md in full up front. Read the mode file (or the relevant section of it) at the point you need it , one question or stage at a time. If a re read via the Read tool is refused as "file unchanged", the prior result was evicted; reload with cat <path via Bash instead. Interview backbone (so you can proceed even if interview.md is unavailable mid session): Q Question Fills schema sections Q1 What are we working on? section 1 context, section 2 assets, section 3 entry points Q2 What can go wrong? section 4 threat rows (id, threat, actor, surface, asset) Q3 What are we going to do about it? section 4 impact/likelihood/status/controls; section 5 deprioritized; section 8 recommended mitigations Q4 Did we do a good job? validate ranking, coverage check, section 6 open questions bootstrap then interview mode When the owner is available and the codebase is checked out, this is the recommended path: the owner's time goes to refining a code grounded draft instead of describing the system from scratch. 1. Tell the owner: "I'll read the code first and come back with a draft (about 5 10 min), then we'll walk it together. Want that, or would you rather start cold?" Only proceed if they opt in; otherwise fall back to interview.md . 2. Read bootstrap.md and follow it end to end. Write <target dir /THREAT MODEL.md . 3. Immediately continue into interview mode: read interview.md and follow it with seed <target dir /THREAT MODEL.md in effect. The section 6 open questions from bootstrap become your Q1 Q4 prompts; the owner confirms, corrects, and adds rather than starting from nothing. 4. Overwrite <target dir /THREAT MODEL.md with the refined model. Set provenance mode: bootstrap then interview . The same flow is available manually: run bootstrap first, then interview seed <THREAT MODEL.md in a later session. Step 2 — Shared output contract All modes MUST emit <target dir /THREAT MODEL.md conforming to schema.md in this directory. Read schema.md immediately before you write the file , not at routing time; in interview mode the gap between routing and emit can be many turns, and an early read will be evicted before it's used. After writing the file, print to the user: 1. The path to THREAT MODEL.md . 2. The top 5 threats by likelihood × impact (id, one line description, L×I). 3. For bootstrap : any open questions the code could not answer (these seed a later interview pass). 4. For interview : any owner statements that could not be verified in code (these seed follow up code review). References [docs/security.md](../../../docs/security.md) and [docs/prompting.md](../../../docs/prompting.md) for the engagement context and authorization framing this skill inherits.

threat-model