CVE-2024-9966 - Exploiting Google Chrome Navigation Flaws to Bypass Content Security Policy

In March 2024, a new vulnerability was assigned: CVE-2024-9966. This flaw was found in the way Google Chrome (before version 130..6723.58) handled site navigation. Here’s what you need to know, how it works, and why you should care—even though it’s ranked as a “Low” severity for Chromium users.

What Is CVE-2024-9966?

CVE-2024-9966 is a vulnerability in the navigation implementation of Google Chrome. If exploited, a remote attacker (someone on the internet) could "bypass content security policy" (CSP). That means they might run scripts or load content on someone else’s website you visit, even if that website has a security policy block in place.

Understanding Content Security Policy (CSP)

CSP is a web security standard to stop malicious code (like XSS attacks). It lets websites tell browsers: “Don’t run anything unless I say so!” If Chrome doesn't check CSP properly when navigating between pages, an attacker might trick Chrome into running code anyway.

The Flaw—Simple Explanation

- Normally, when you click a link or are redirected in Chrome, the browser checks the destination site’s CSP rules.
- But before Chrome 130..6723.58, Chrome didn't enforce these rules right during certain navigation events.
- A hacker could create a special HTML page that manipulates navigation to another site while inserting malicious content—because Chrome forgot to enforce the strict content security policy at the right time.

Here’s a basic outline of how the exploit works

1. The Attacker’s Page: Someone builds a webpage with JavaScript that opens a new window or iframe to the target site.
2. Trick Chrome: The attacker manipulates navigation flow (using window.open, window.location, or postMessage).
3. Chrome Fumbles CSP: Chrome fails to apply the right CSP during the navigation, letting attacker’s scripts or content leak into the next page.

Example Exploit (Proof-of-Concept)

Suppose a site https://victim.com uses CSP to block inline scripts. An attacker can try something like this:

<!-- attacker.html -->
<!DOCTYPE html>
<html>
  <body>
    <script>
      // Open victim.com in a new window
      let popup = window.open('https://victim.com');

      // Wait a bit, then try to inject content via navigation shenanigans
      setTimeout(() => {
        // Navigate the popup back to an attacker-controlled page
        popup.location = 'data:text/html,<script>alert("CSP bypassed!")</script>';
      }, 100);
    </script>
    <p>If this works, Chrome let the script run, ignoring Victim's CSP.</p>
  </body>
</html>

What’s happening:

- Chrome, due to the bug, does not reapply the original CSP when loading this new content, so the script runs.

Links to the Original References

- Chromium Bug Tracker #402376
- CVE-2024-9966 at NVD
- Google Chrome Releases Blog

Why Does It Matter?

- Phishing & Info Theft: Attackers could fool you into running scripts or leaking information on secure websites.
- Web Trust: Sites using CSP *think* they're safe, but browsers don’t always respect their wishes!
- Everyone Needs Updates: Because browsers touch everything, even “low” bugs can add up with others.

Mitigation

Upgrade Chrome to version 130..6723.58 or above.
Other Chromium-based browsers (like Edge, Opera, Brave, etc.) may also need an update.

Conclusion

CVE-2024-9966 is a textbook example of how small browser bugs can undermine web security. It shows why keeping browsers updated is critical, and why web security is so tough: one tiny slip, and the whole chain of trust can break.

Always keep your browser up to date, and let tech folks know if you’re building a website: *Never* rely *only* on browsers to enforce security—you must test, watch for vulnerabilities, and patch early and often.

Stay safe, and happy browsing!

*This article was created exclusively for you—written in plain English, with direct code and current links. If you have browser security concerns or want more coverage of new CVEs, let us know!*

Timeline

Published on: 10/15/2024 21:15:12 UTC
Last modified on: 10/17/2024 20:12:09 UTC