CVE CyberSecurity Database News

CVE-2023-3421 - Understanding and exploiting the 'Use After Free' vulnerability in Google Chrome Media

Poster -

A high-severity vulnerability (CVE-2023-3421) has been identified in Google Chrome versions prior to 114..5735.198. The issue is a Use After Free (UAF) vulnerability in the Media component, which allows a remote attacker to potentially exploit heap corruption via a specially crafted HTML page. In this article, we will delve into the details of this vulnerability, including code snippets, links to original references, and an explanation of its exploit.

What is Use After Free?
'Use After Free' is a type of memory corruption vulnerability that occurs when an allocated memory block, which has been freed by the developer, is subsequently used by another part of the program. An attacker who successfully exploits a UAF vulnerability can overwrite data or execute arbitrary code by controlling the contents of the freed memory block.

Details of CVE-2023-3421

In the case of CVE-2023-3421, the vulnerable component is Media. Google Chrome's Media component is responsible for handling multimedia content such as audio and video. The vulnerability in this component can be exploited by an attacker constructing a malicious HTML page which, when rendered by the target's browser, will trigger heap corruption, potentially leading to arbitrary code execution.

Exploit Details

The exact details of exploiting a UAF vulnerability vary depending on the software in question. In the case of CVE-2023-3421, an attacker could potentially allocate and then free a memory block related to a multimedia object within the HTML page. They could then force the browser to access the freed memory block, allowing them to exploit the heap corruption by overwriting the contents of the memory block and executing arbitrary code.

Here is a simplified code snippet that demonstrates the concept of exploiting a UAF vulnerability

<!DOCTYPE html>
<html>
  <head>
    <script>
      function triggerUAF() {
        // Allocate memory block by creating a multimedia object
        let video = document.createElement("video");
        video.src = "malicious_video.mp4";

        // Free the memory block by setting the source to null
        video.src = null;

        // Exploit: Access the freed memory block
        // (implementation details vary)
        /* ... */
      }
    </script>
  </head>
  <body onload="triggerUAF();">
    <h1>Malicious Page</h1>
  </body>
</html>

It should be noted that the code snippet provided is a simplified example and serves only to demonstrate the concept of UAF exploitation. Real-world exploitation would require a more sophisticated approach to exploiting this or other UAF vulnerabilities.

Mitigation

The most effective way to protect against CVE-2023-3421 is by updating to the latest version of Google Chrome (114..5735.198 or later). By keeping your software up to date, you can ensure that known security vulnerabilities are patched and that you have the best possible protection against attackers.

Conclusion

CVE-2023-3421 is a high-severity Use After Free vulnerability in Google Chrome's Media component, which could allow heap corruption and arbitrary code execution by a remote attacker. Ensuring your software is up to date is the best way to protect against this and other security vulnerabilities.

- Google Chrome Release Notes
- Chromium Security Advisory
- CVE-2023-3421 Details (NVD)

Remember to always keep your software up to date, be vigilant about which websites you visit, and report any suspicious or compromised websites to ensure a safer browsing experience for everyone.

Timeline

Published on: 06/26/2023 21:15:00 UTC
Last modified on: 09/25/2023 19:15:00 UTC