hunt-dom

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> This skill is for educational purposes or authorized security assessments only.

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> Misuse of this tool is illegal and strictly prohibited.

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> Before running any command that probes, exploits, changes, persists on, extracts data from, or attempts credential access against a target:

> 1. Ask the user to state the exact target URL, IP, account, or resource.

> 2. Ask the user to confirm written authorization and the permitted scope.

> 3. Show the exact command(s) and explain their expected effect.

> 4. Wait for explicit confirmation in the current conversation.

>

> Without that confirmation, remain read-only and provide defensive guidance only. Prefer a sandbox, disposable VM, or controlled lab.

# HUNT-DOM — DOM Clobbering / PostMessage / Service Worker / CSS Exfil

Crown Jewel Targets

DOM-based attacks execute in the victim's browser — the server often never sees the payload, so WAFs and server-side input filters do not apply. PostMessage missing-origin-check = cross-origin token theft with no XSS needed.

**Highest-value chains:**

- **DOM Clobbering → DOM-XSS / auth bypass** — HTML *markup* injection (no `<script>`) overwrites a JS global like `window.config` or shadows `document.getElementById`, and the app later treats that value as a URL/code → sink fires under a markup-only injection where script is filtered.

- **PostMessage no origin check → session theft / DOM-XSS** — a `message` handler that trusts `event.data` without validating `event.origin` lets an attacker iframe/opener drive privileged actions or feed a sink.

- **Service Worker abuse** — register a **same-origin** SW script (reachable because of an upload / open-redirect / path the target serves) via stored XSS → intercept all in-scope `fetch` → persistent credential capture.

- **CSS Exfil** — attribute-value selectors (`input[value^="a"]`) leak a CSRF token / API key / nonce char-by-char to an OOB host with zero JS.

Grounding — public research this is distilled from

- **DOM Clobbering / DOM-Invader** — Gareth Heyes & the PortSwigger Web Security Academy "DOM clobbering" topic; DOM-Invader ships a dedicated clobbering scanner. Sink taxonomy maps to the academy's DOM-based vulnerability labs.

- **DOMPurify clobbering & mXSS bypasses** — Michał Bentkowski (Securitum) blog series on bypassing HTML sanitizers via clobbering and mutation XSS.

- **jQuery `htmlPrefilter` self-closing-tag XSS** — **CVE-2020-11022** and **CVE-2020-11023** (jQuery < 3.5.0). Passing attacker HTML to `.html()` / `.append()` mutates into executing markup. Grep bundled jQuery version; this is one of the most common real-world DOM-XSS roots.

- **CSS exfiltration** — d0nut "CSS Injection Attacks" / "Stealing Data With CSS" research (sequential `@import` recursion to drop the per-char-position constraint).

> Cite only what you reproduce. Do not paste these as "proof" in a report — your PoC against the live target is the evidence. Named research here is for *technique provenance*, not severity inflation.

---

Attack Surface Signals

# Injection points that allow MARKUP but may strip <script>:
user bio / display name / comment / markdown preview / SVG upload / CMS rich-text

# postMessage endpoints (iframes, SSO widgets, payment frames, chat widgets):
*/sso/*  */embed/*  */widget/*  */oauth/*  /sdk.js  pay/checkout iframes

# Service worker presence:
/sw.js  /service-worker.js  /firebase-messaging-sw.js  /ngsw-worker.js (Angular)

# CSS injection points:
?theme=  custom-css profile field  email-template editor  style= passthrough

---

Phase 1 — DOM Clobbering

# Signal: app reads element IDs/names as if they were JS objects, OR feeds a
# clobberable global into a sink (location, innerHTML, eval, script.src).
# Inject MARKUP (no script) at a sink that lets named/id'd elements through.

# Single-level clobber of windo