passive-listen

Purpose

CT podcast methodology (Matanber Ep ~100, Renee, Frans Rosén, Yusuf) emphasizes dynamic-first JS hunting: get intimate with the app, let extensions log every DOM source/sink/listener as you click, then read JS only for flagged paths.

This skill formalizes that pattern. While the user (or Claude) drives the browser, the skill snapshots three extension stores plus Caido network capture on a poll interval. Output feeds later chain-triage + opus-deep-audit (a hot chain whose source actually fired at runtime ranks higher than one whose did not).

When to fire

• User explicitly says "passive listen for N min" / invokes /passive-listen.
• A long static job (extract_chains, rag-ingest, opus-deep-audit) is in background AND memory.md rule parallel-dynamic-static says don't sit idle.
• Start of an engagement before any audit, to seed runtime evidence.

Inputs

• targets/<name>/status.json for scope hosts.
• A live @browser tab on the target. Caller must have ensured caido-capture is set up first.
• Optional: poll interval in seconds (default 30).
• Optional: total session minutes (default 15).

Required Chrome extensions

• DOMLogger++ — DOM source/sink hooks
• postMessage-tracker (fransr) — listener registration capture
• Gecko (Caleb Gross) — sink-context payload candidate detection
• FoxyProxy + Caido browser plugin — request capture

If any are missing, the skill still runs but the corresponding store in state.json will be null. Log this in the per-session summary.

Outputs

• targets/<name>/runtime/<utc-iso>/state.json per poll iteration
• targets/<name>/runtime/_log.jsonl rolling one-line summary
• targets/<name>/runtime/<utc-iso>/caido_delta.json new requests captured since last poll (queried via caido_list_requests)
• Final session summary at targets/<name>/runtime/_session_<ts>.md with:
  • URLs visited
  • Distinct DOMLogger++ sources observed (param names, value samples sanitized)
  • Distinct postMessage listeners registered (file + line if available)
  • Forms encountered
  • New JS chunks captured by Caido
  • Inline-handler attribute count

Flow

1. Read status.json.active_focus_hosts and status.json.tier1_hosts.
2. Confirm @browser tab present via tabs_context_mcp. If not, fail loudly.
3. Pre-flight state dump:

   snippet = `python3 bin/dump_browser_state.py --snippet`
   result  = mcp__claude-in-chrome__javascript_tool(snippet, tabId)
   echo "$result" > /tmp/state.json
   python3 bin/dump_browser_state.py --persist /tmp/state.json <name>
   

4. Concurrently: mcp__caido__caido_list_requests filtered to in-scope hosts; save to runtime/<ts>/caido_delta.json.
5. Sleep poll_interval_s.
6. Repeat steps 3-5 until session-minutes elapsed OR user says "stop".
7. After the loop, emit runtime/_session_<ts>.md with synthesized findings.

Dialog hazard

Per feedback_browser_mcp_chrome_only, claude-in-chrome MCP freezes when JS alerts pop. DOMLogger++ default config may pop alerts on suspected XSS. Inject window.alert = console.log at session start (already done by js-harvest / browser-confirm skills). Skill re-injects defensively at every poll.

Result block (status.json)

"phases": {
  "passive_listen": {
    "status": "done",
    "ts": "<iso>",
    "session_minutes": 15,
    "polls": 30,
    "domlogger_events_total": 412,
    "postmessage_listeners_total": 17,
    "gecko_sinks_total": 5,
    "new_chunks_observed": 23,
    "summary_path": "targets/<name>/runtime/_session_<ts>.md"
  }
}

What to do AFTER passive-listen

• Re-run chain-triage with the runtime evidence — chains whose source name matches an observed DOMLogger++ source bump up the priority queue.
• Re-run js-harvest if new_chunks_observed > 0. Re-index + re-isolate + re-triage. The fresh chunks usually include MFEs the initial walk missed (account-edit, product-detail, checkout-deep, customer-service).
• Feed postmessage_listeners_total set into a tagged chain-triage filter: any chain whose entry function is one of these listeners gets explicit Opus audit attention.

Failure modes

• @browser MCP disconnects mid-session: pause loop, surface to user, retry on next manual tabs_context_mcp.
• DOMLogger++ store globals not present (extension disabled / not loaded): fall back to injecting bin/domlogger_payload.js via javascript_tool so we at least get TLX-payload events.
• Caido requests query fails: continue browser-side capture; flag in session summary.
• User navigates to out-of-scope host: skip that poll's caido_delta, retain browser-side dump (still useful for hostname / external-resource recon).