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What Is CVE-2023-4907?

CVE-2023-4907 is a low-severity security vulnerability that impacted Google Chrome for Android, specifically versions prior to 117..5938.62. The problem was due to the inappropriate implementation of Intents, which allowed a remote attacker to mess with (obfuscate) security UI. This kind of trickery could be triggered just by getting a user to visit a specially crafted HTML page.

In simple language: someone could make Chrome show a confusing security prompt, or hide important warning information, using code in a webpage.

Let’s break down what happened, how it worked, and what you can do about it.

Type: Inappropriate implementation of Intents

- Result: Remote attacker can obfuscate (hide/mask) parts of the browser security interface

Why Should You Care?

This isn't a "full device takeover," but UI obfuscation can trick users into missing important security warnings, like when you're about to be redirected somewhere or open content in another app. It opens the door for clever phishing or misdirection attacks, especially for less experienced users.

How Did The Vulnerability Work?

Chrome for Android uses Intents to handle actions like opening a link in another app. Normally, Chrome shows clear UI elements when it's about to hand off your data (like a warning banner or prompt). Because of this bug, a webpage could send a malicious Intent in a way that the browser’s usual protective UI was hidden or made confusing.

A remote attacker could embed a crafted HTML page containing JavaScript that interacts with Chrome’s Intent system. Instead of waiting for the user to confirm, the crafted code could "cover up" the browser's prompts (or alter their appearance)—potentially hiding the fact you're leaving Chrome, authorizing an app, or giving up data.

Here’s a simplified code snippet of how a crafted HTML page might trigger this bug

<!DOCTYPE html>
<html>
<head>
<title>Intent Exploit Demo</title>
</head>
<body>
<script>
// This simulates a navigation to a malicious Intent URI
window.location = 'intent://example.com/#Intent;scheme=http;package=com.badapp.android;end';
</script>
<p>If you see this message, your browser tried to handle an Intent.</p>
</body>
</html>

Launch another app via Intent without clear UI confirmation, or

2. Overlap/cover/hide security warnings using other HTML tricks.

The problem was Chrome's UI didn't always isolate or display the warning correctly.

Impact

- Tricked Users: Attackers could make a malicious webpage that covered up Chrome's security warnings.
- Phishing: Could make a user think they're still inside Chrome, or that a legitimate action is taking place, when they're actually doing something risky.

Forced Chrome to always show clear, un-obscured security UI,

- Improved isolation (so web content couldn't cover up browser/UI prompts).

References:
- Chromium Issue 1483377
- Google Chrome Releases (Official Notes)
- CVE Page - NVD

Update Chrome for Android now! (Or make sure you have 117..5938.62 or later.)

- Be careful of odd popups or prompts when browsing, especially if the page “looks” like it’s not showing Chrome’s standard UI.
- Report suspicious-looking sites (especially those that redirect or open apps without clear warnings).

Final Thoughts

CVE-2023-4907 might be low severity, but it’s an example of how little UI bugs can erode user trust. Chrome’s Intent system is powerful, but needs concrete defenses so attackers can’t exploit the bridge between web pages and apps. Always update your browser, and watch out for web pages that ask to launch apps or take you somewhere outside your browser!


TL;DR: Old Chrome versions on Android could be tricked into hiding important security warnings using Intent mischief. Update your browser to stay safe!


If you want even deeper technical details or want to see how Chromium’s team fixed it, hit these links:

- Chromium Bug Report
- NVD Entry

Timeline

Published on: 09/12/2023 21:15:08 UTC
Last modified on: 10/17/2023 20:02:45 UTC