feat: initial MV3 detection markers

Nine benign Chrome MV3 detection markers for validating browser extension
security scanners. Each marker exercises one suspicious-behavior signature
without performing real data capture or exfiltration.

Educational and defensive-testing use only. See LICENSE.

.gitignore

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+.DS_Store
+Thumbs.db
+*.log
+*.swp
+*.tmp
+.env
+.env.*
+node_modules/
+.idea/
+.vscode/
+*.crx
+*.pem

LICENSE

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+MIT License
+
+Copyright (c) 2026 <author>
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+------------------------------------------------------------------------------
+EDUCATIONAL-USE NOTICE
+------------------------------------------------------------------------------
+
+This Software is provided for EDUCATIONAL and DEFENSIVE SECURITY TESTING
+purposes only. The benign detection markers contained herein are designed to
+validate browser-extension security scanners and contain no working
+credential-theft, exfiltration, or surveillance logic.
+
+By using the Software you agree:
+
+1. You will only load these markers in browser profiles, devices, and networks
+   that you own, or for which you have explicit written authorization to test.
+2. You will not use the Software to harass, deceive, defraud, surveil, or
+   cause harm to any person or system.
+3. You are solely responsible for ensuring your use of the Software complies
+   with all applicable laws, regulations, employer policies, and the terms of
+   service of any browser, platform, or service involved.
+4. You assume all risk associated with the Software, including but not limited
+   to data loss, account suspension, EDR/AV quarantine actions, and any other
+   adverse consequence.
+
+------------------------------------------------------------------------------
+DISCLAIMER
+------------------------------------------------------------------------------
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

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+# MV3 Detection Markers
+
+> ## ⚠️ Educational Use Only — Use at Your Own Risk
+>
+> This project provides **benign** Chrome MV3 extensions ("detection markers") for validating browser-extension security scanners. It is the EICAR-equivalent pattern for browser-extension detection.
+>
+> - **Educational and defensive-testing purpose only.** Do not use for any unlawful activity.
+> - **No working credential-theft logic.** Markers exercise suspicious *manifest patterns* and *API call shapes*. They do **not** read or transmit real keystrokes, password values, cookie values, or clipboard contents.
+> - **Only load on systems and in browser profiles you own or have written authorization to test.** Do not deploy against third parties.
+> - **You assume all risk.** The authors and contributors accept no liability for misuse, data loss, or any consequence of running this software. See `LICENSE`.
+>
+> If you cannot agree to the above, do not use this project.
+
+---
+
+Benign Chrome MV3 extensions that trigger specific suspicious-behavior signatures. Used as test cases for enterprise extension scanners.
+
+**No real user data is captured or exfiltrated.** Each marker exercises one detection category and logs a literal marker string (and optionally POSTs to a local test endpoint).
+
+---
+
+## Test endpoint setup (optional)
+
+Markers 02 and 03 POST to `http://127.0.0.1:8080/marker`. To capture those POSTs, run any local logger before loading:
+
+```bash
+# Quick netcat logger (echoes raw request)
+while true; do nc -l -p 8080 -q 1; done
+
+# Or a small Python catcher
+python3 -c "
+from http.server import BaseHTTPRequestHandler, HTTPServer
+class H(BaseHTTPRequestHandler):
+    def do_POST(self):
+        n = int(self.headers.get('content-length', 0))
+        print(self.rfile.read(n).decode(errors='replace'))
+        self.send_response(204); self.end_headers()
+HTTPServer(('127.0.0.1', 8080), H).serve_forever()
+"
+```
+
+If you skip this, the `fetch` calls silently fail and markers still log to the extension's service-worker / content-script console.
+
+---
+
+## Load procedure
+
+1. Open `chrome://extensions` (Chrome MV3) or `brave://extensions` (Brave).
+2. Toggle **Developer mode** (top right).
+3. **Load unpacked** → pick one marker folder.
+4. Note the generated extension ID.
+5. Run your scanner against:
+   - the folder (static analysis), and
+   - the loaded extension ID (dynamic / runtime analysis).
+6. Record verdict per marker.
+
+For marker 09 (manifest-delta), load `v1-narrow` first, run scanner, then remove and load `v2-wide`. Scanner should flag the permission expansion as a delta-based signal.
+
+---
+
+## Marker matrix
+
+| # | Folder | Detection signal | Real-world example |
+|---|---|---|---|
+| 01 | `01-form-hook` | Content script attaches `keydown` listener to `input[type=password]` on `<all_urls>` | Credential keylogger pattern |
+| 02 | `02-cookie-read` | Service worker calls `chrome.cookies.getAll({})` on install | Session theft pattern (Cyberhaven cluster) |
+| 03 | `03-beacon-c2` | `chrome.alarms` periodic POST to external host | C2 beaconing |
+| 04 | `04-dnr-redirect` | `declarativeNetRequest` static redirect rule | MV3-only attack vector (replaces MV2 webRequest blocking) |
+| 05 | `05-broad-perms` | `<all_urls>` host perm + cookies + scripting + webRequest + tabs combo | Manifest-only signal — pure static test |
+| 06 | `06-programmatic-inject` | `chrome.scripting.executeScript` on every tab `complete` event | Stealth content-script injection without `content_scripts` declaration |
+| 07 | `07-clipboard-read` | `navigator.clipboard.readText()` on Ctrl+V | Clipboard-stealer pattern |
+| 08 | `08-tab-capture` | `chrome.tabs.captureVisibleTab` on action click | Screen-grabber pattern |
+| 09 | `09-manifest-delta` | v1 narrow scope → v2 widens to `<all_urls>` + cookies + scripting | Update-poisoning pattern (Cyberhaven technique) |
+
+---
+
+## What these markers do NOT do
+
+- Do not read keystroke values, password contents, cookie values, or clipboard text.
+- Do not transmit any data to non-local destinations.
+- Do not persist anything to disk or `chrome.storage`.
+- Do not modify form behavior, page DOM, or user actions.
+
+Safe to load in a disposable Brave/Chrome dev profile. A clean VM is still recommended so any false-positive enterprise EDR action doesn't disrupt your daily browser.
+
+---
+
+## Per-category recall scoring
+
+For each marker, record:
+
+| Marker | Scanner verdict | Detection rule fired | Notes |
+|---|---|---|---|
+| 01 | flagged / clean | | |
+| 02 | | | |
+| ... | | | |
+
+Anything in the **clean** column → a gap. Cross-reference to the prior detection-category report (`research-260516-0713-malicious-chrome-extension-samples-for-detection-testing.md`, §2) to map the miss to a missing rule type.
+
+---
+
+## Removing markers
+
+Each is its own extension — remove via `chrome://extensions` → trash icon. No system changes, no registry keys, no leftover files.
+
+---
+
+## Unresolved
+
+1. **Manifest delta `key` field.** For scanners that require both versions to share an extension ID (i.e., compare by ID), you must inject a stable `key` field into both `manifest.json` files. Generate one with `chrome` packing the v1 folder once and copying the resulting public key. Skipped here because most static scanners diff by name/folder; flag this if your scanner needs ID-stability.
+2. **MV2 counterparts** for any of the above markers can be added when you're ready — say the word and I'll generate them alongside.

markers/01-form-hook/content.js

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+// MARKER 01 - Form Hook
+// Detection target: keystroke listener attached to password inputs.
+// SAFETY: does NOT read event.key or input value. Logs marker string only.
+
+const MARKER = "MARKER_01_FORM_HOOK";
+
+function attachListeners() {
+  const fields = document.querySelectorAll("input[type=password]");
+  if (fields.length === 0) return;
+  fields.forEach((field) => {
+    if (field.dataset.markerAttached) return;
+    field.dataset.markerAttached = "1";
+    field.addEventListener("keydown", () => console.log(`${MARKER} keydown`));
+    field.addEventListener("input", () => console.log(`${MARKER} input`));
+  });
+  console.log(`${MARKER} attached to ${fields.length} password field(s)`);
+}
+
+attachListeners();
+new MutationObserver(attachListeners).observe(document.documentElement, {
+  childList: true,
+  subtree: true,
+});

markers/01-form-hook/manifest.json

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+{
+  "manifest_version": 3,
+  "name": "Marker 01 - Form Hook",
+  "version": "1.0.0",
+  "description": "Detection marker: content script attaches keystroke listener to password fields. No data captured.",
+  "content_scripts": [
+    {
+      "matches": ["<all_urls>"],
+      "js": ["content.js"],
+      "run_at": "document_idle"
+    }
+  ]
+}

markers/02-cookie-read/manifest.json

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+{
+  "manifest_version": 3,
+  "name": "Marker 02 - Cookie Read",
+  "version": "1.0.0",
+  "description": "Detection marker: enumerates cookies via chrome.cookies API. No cookie values transmitted.",
+  "permissions": ["cookies"],
+  "host_permissions": ["<all_urls>"],
+  "background": { "service_worker": "service-worker.js" }
+}

markers/02-cookie-read/service-worker.js

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+// MARKER 02 - Cookie Read
+// Detection target: chrome.cookies.getAll() enumeration from service worker.
+// SAFETY: counts cookies, logs count, POSTs count-only to local test endpoint.
+// Cookie values are NOT transmitted or persisted.
+
+const MARKER = "MARKER_02_COOKIE_READ";
+
+chrome.runtime.onInstalled.addListener(() => {
+  chrome.cookies.getAll({}, (cookies) => {
+    const count = cookies.length;
+    console.log(`${MARKER} enumerated ${count} cookies (values discarded)`);
+    fetch("http://127.0.0.1:8080/marker", {
+      method: "POST",
+      body: `${MARKER}_COUNT=${count}`,
+    }).catch(() => {});
+  });
+});

markers/03-beacon-c2/manifest.json

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+{
+  "manifest_version": 3,
+  "name": "Marker 03 - Beacon C2",
+  "version": "1.0.0",
+  "description": "Detection marker: periodic beacon via chrome.alarms to local test endpoint.",
+  "permissions": ["alarms"],
+  "host_permissions": ["http://127.0.0.1/*"],
+  "background": { "service_worker": "service-worker.js" }
+}

markers/03-beacon-c2/service-worker.js

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+// MARKER 03 - Beacon C2
+// Detection target: service worker schedules periodic external POST via chrome.alarms.
+// SAFETY: body is the literal marker string. No user/system data is read or sent.
+
+const MARKER = "MARKER_03_BEACON_C2";
+
+chrome.runtime.onInstalled.addListener(() => {
+  chrome.alarms.create("marker-beacon", { periodInMinutes: 1 });
+  console.log(`${MARKER} alarm scheduled`);
+});
+
+chrome.alarms.onAlarm.addListener((alarm) => {
+  if (alarm.name !== "marker-beacon") return;
+  console.log(`${MARKER} beacon fired`);
+  fetch("http://127.0.0.1:8080/marker", {
+    method: "POST",
+    body: MARKER,
+  }).catch(() => {});
+});

markers/04-dnr-redirect/manifest.json

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+{
+  "manifest_version": 3,
+  "name": "Marker 04 - DNR Redirect",
+  "version": "1.0.0",
+  "description": "Detection marker: declarativeNetRequest redirect rule for an invalid TLD.",
+  "permissions": ["declarativeNetRequest"],
+  "host_permissions": ["*://marker-test.invalid/*"],
+  "declarative_net_request": {
+    "rule_resources": [
+      {
+        "id": "marker-rules",
+        "enabled": true,
+        "path": "rules.json"
+      }
+    ]
+  }
+}

markers/04-dnr-redirect/rules.json

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+[
+  {
+    "id": 1,
+    "priority": 1,
+    "action": {
+      "type": "redirect",
+      "redirect": { "url": "https://example.com/marker-04-dnr-redirect" }
+    },
+    "condition": {
+      "urlFilter": "marker-test.invalid",
+      "resourceTypes": ["main_frame"]
+    }
+  }
+]

markers/05-broad-perms/manifest.json

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+{
+  "manifest_version": 3,
+  "name": "Marker 05 - Broad Permissions",
+  "version": "1.0.0",
+  "description": "Detection marker: oversized permission combo. No behavior beyond a console log.",
+  "permissions": [
+    "cookies",
+    "scripting",
+    "webRequest",
+    "storage",
+    "tabs",
+    "alarms",
+    "clipboardRead"
+  ],
+  "host_permissions": ["<all_urls>"],
+  "background": { "service_worker": "service-worker.js" }
+}

markers/05-broad-perms/service-worker.js

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+// MARKER 05 - Broad Permissions
+// Detection target: manifest declares oversized permission combo.
+// Behavior: none. Pure static-analysis test.
+
+console.log("MARKER_05_BROAD_PERMS loaded");

markers/06-programmatic-inject/injected.js

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+// MARKER 06 injected payload. Logs marker string only.
+console.log("MARKER_06_INJECTED_PAYLOAD");

markers/06-programmatic-inject/manifest.json

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+{
+  "manifest_version": 3,
+  "name": "Marker 06 - Programmatic Inject",
+  "version": "1.0.0",
+  "description": "Detection marker: chrome.scripting.executeScript on every tab complete event.",
+  "permissions": ["scripting", "tabs"],
+  "host_permissions": ["<all_urls>"],
+  "background": { "service_worker": "service-worker.js" }
+}

markers/06-programmatic-inject/service-worker.js

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+// MARKER 06 - Programmatic Inject
+// Detection target: chrome.scripting.executeScript injection on tab events,
+// bypassing the static content_scripts declaration.
+
+const MARKER = "MARKER_06_PROGRAMMATIC_INJECT";
+
+chrome.tabs.onUpdated.addListener((tabId, info, tab) => {
+  if (info.status !== "complete") return;
+  if (!tab.url || !tab.url.startsWith("http")) return;
+  chrome.scripting
+    .executeScript({ target: { tabId }, files: ["injected.js"] })
+    .then(() => console.log(`${MARKER} injected into tab ${tabId}`))
+    .catch(() => {});
+});

markers/07-clipboard-read/content.js

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+// MARKER 07 - Clipboard Read
+// Detection target: navigator.clipboard.readText() triggered by user input.
+// SAFETY: discards clipboard content; logs length only.
+
+const MARKER = "MARKER_07_CLIPBOARD_READ";
+
+document.addEventListener("keydown", async (e) => {
+  if (!(e.ctrlKey && e.key === "v")) return;
+  try {
+    const text = await navigator.clipboard.readText();
+    console.log(`${MARKER} length=${text.length} (content discarded)`);
+  } catch {
+    /* permission may not be granted yet */
+  }
+});

markers/07-clipboard-read/manifest.json

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+{
+  "manifest_version": 3,
+  "name": "Marker 07 - Clipboard Read",
+  "version": "1.0.0",
+  "description": "Detection marker: reads clipboard on Ctrl+V. Content discarded.",
+  "permissions": ["clipboardRead"],
+  "content_scripts": [
+    {
+      "matches": ["<all_urls>"],
+      "js": ["content.js"],
+      "run_at": "document_idle"
+    }
+  ]
+}

markers/08-tab-capture/manifest.json

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+{
+  "manifest_version": 3,
+  "name": "Marker 08 - Tab Capture",
+  "version": "1.0.0",
+  "description": "Detection marker: chrome.tabs.captureVisibleTab on action click. Capture discarded.",
+  "permissions": ["activeTab"],
+  "host_permissions": ["<all_urls>"],
+  "action": { "default_title": "Marker 08 - Click to test capture" },
+  "background": { "service_worker": "service-worker.js" }
+}

markers/08-tab-capture/service-worker.js

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+// MARKER 08 - Tab Capture
+// Detection target: chrome.tabs.captureVisibleTab.
+// SAFETY: capture data URL is discarded immediately, never transmitted.
+
+const MARKER = "MARKER_08_TAB_CAPTURE";
+
+chrome.action.onClicked.addListener(() => {
+  chrome.tabs.captureVisibleTab({ format: "png" }, (dataUrl) => {
+    if (!dataUrl) return;
+    console.log(`${MARKER} captured tab, size=${dataUrl.length} (discarded)`);
+  });
+});

markers/09-manifest-delta/v1-narrow/manifest.json

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+{
+  "manifest_version": 3,
+  "name": "Marker 09 - Manifest Delta",
+  "version": "1.0.0",
+  "description": "Detection marker v1: narrow scope (example.com only, storage only).",
+  "permissions": ["storage"],
+  "host_permissions": ["https://example.com/*"],
+  "background": { "service_worker": "service-worker.js" }
+}

markers/09-manifest-delta/v1-narrow/service-worker.js

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+// MARKER 09 v1 - Narrow Scope
+// Baseline manifest. Load first; run scanner; verdict should be clean / low risk.
+console.log("MARKER_09_V1_NARROW loaded");

markers/09-manifest-delta/v2-wide/manifest.json

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+{
+  "manifest_version": 3,
+  "name": "Marker 09 - Manifest Delta",
+  "version": "2.0.0",
+  "description": "Detection marker v2: widened scope (simulates post-update compromise).",
+  "permissions": ["storage", "cookies", "scripting", "webRequest", "tabs"],
+  "host_permissions": ["<all_urls>"],
+  "background": { "service_worker": "service-worker.js" }
+}

markers/09-manifest-delta/v2-wide/service-worker.js

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+// MARKER 09 v2 - Wide Scope
+// Compromise-update manifest. Load after v1; scanner should flag the permission delta.
+console.log("MARKER_09_V2_WIDE loaded");