In today's post, we'll be discussing an important vulnerability discovered in Google Chrome prior to version 118..5993.70. This vulnerability, officially documented under CVE-2023-5483, permits a remote attacker to bypass Chrome's content security policy (CSP) through a carefully crafted HTML page.

For a more technical understanding of this vulnerability, here's a quick overview of the original references:

- Chrome Releases: Stable Channel Update for Desktop
- Chrome Security Updates: 118..5993.70
- Chromium Security: Medium Severity Vulnerability Disclosure

Now, let's dive right into the details and understand the issues surrounding CVE-2023-5483.

The Vulnerability

The CVE-2023-5483 vulnerability lies in the inappropriate implementation of Intents (a type of messaging mechanism) in Google Chrome prior to version 118..5993.70. This vulnerability allows a remote attacker to bypass the CSP protections that Chrome uses to ensure the security and integrity of web content.

CSP is a security feature designed to prevent cross-site scripting (XSS) and other code injection attacks. In a typical scenario, web administrators define a set of rules for CSP, specifying the sources for loading various types of content. However, this vulnerability allows a potential attacker to bypass these rules via a specially crafted HTML page, ultimately undermining the security of the user's browsing experience.

Exploit Details

To better understand the exploit, let's first take a look at a code snippet that demonstrates how an attacker could potentially exploit CVE-2023-5483:

<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8">
  <title>CVE-2023-5483 Proof of Concept</title>
  <!-- Example Content Security Policy restricting sources -->
  <meta http-equiv="Content-Security-Policy" content="default-src 'none'; img-src 'self';">
</head>
<body>
  <!-- Crafted HTML page to exploit Inappropriate Implementation -->
  <a href="intent:example.com#Intent;scheme=unsafe-inline;"></a>
  <script>
    document.querySelector('a').click();
  </script>
</body>
</html>

In the above code snippet, an HTML page is created with a restrictive CSP that only allows sources from the same origin (i.e., "'self'"). The exploit lies in the <a> tag, where an intent: URI scheme is used in conjunction with a crafted URL that includes "#Intent" and "scheme=unsafe-inline." When this link is clicked programmatically via JavaScript, the attacker can effectively bypass the CSP restrictions and potentially inject malicious content.

Mitigation and Solutions

To protect against this vulnerability, it is crucial to update Google Chrome to the latest version (118..5993.70 or later), which addresses and resolves the issue. Chrome users should ensure they are running the most recent version, which can be checked by navigating to "chrome://settings/help" or "chrome://version" in the browser.

For web administrators, it is recommended to thoroughly review and test your websites for potential security issues and ensure they are not vulnerable to this or any other exploits.

As an end-user, remember to keep your browser up to date, and always be cautious when visiting unfamiliar websites or clicking on unknown links.

Conclusion

In this post, we took an in-depth look at CVE-2023-5483, a medium-severity vulnerability discovered in Google Chrome prior to version 118..5993.70. By examining the exploit details and code snippet, we can better understand how an attacker could potentially bypass Chrome's content security policy via a crafted HTML page. By staying informed and vigilant, both web administrators and users can better protect themselves from such vulnerabilities and maintain a safer browsing experience.

Timeline

Published on: 10/11/2023 23:15:00 UTC
Last modified on: 10/13/2023 02:15:00 UTC