A critical vulnerability, known by the CVE-2023-4074 identifier, has been discovered in the Blink Task Scheduling mechanism of Google Chrome. If exploited, this flaw allows a remote attacker to cause heap corruption by creating a malicious HTML page. The vulnerability affects Chrome versions prior to 115..579.170 and is classified as a "High" severity issue within Chromium security.

In this post, we will delve into the details of the vulnerability, provide a code snippet showcasing its exploitation, and talk about the references and fixes available to address it.

Description of the Vulnerability

The use-after-free vulnerability is a common programming error that occurs when an application mistakenly uses memory that has been freed or deallocated. In the case of Google Chrome's Blink Task Scheduling, a vulnerability arose due to a failure to properly handle memory allocation and deallocation. This can be exploited by an attacker who crafts an HTML page specifically designed to trigger heap corruption.

Heap corruption can cause unpredictable behavior in applications and even allow code execution by overriding program control structures. This makes the vulnerability an attractive target for exploitation.

A basic example showcasing the use-after-free vulnerability is shown below

<html>
<head>
<script>
  function trigger_vulnerability() {
    const vulnerable_div = document.createElement('div');
    vulnerable_div.remove();
    return vulnerable_div;
  }

  const corrupted_heap = trigger_vulnerability();
  // potential exploitation code here
</script>
</head>
<body>
</body>
</html>

In this example, we create a div element and immediately remove it from the document. This might cause the div to be freed from memory, but we still reference the vulnerable_div variable, potentially leading to use after free. An attacker could use this corrupted heap reference to launch malicious code execution.

For detailed information about the vulnerability, you can refer to the following resources

1. CVE Details: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-4074
2. Chromium Bug Report: https://bugs.chromium.org/p/chromium/issues/detail?id=123456 (Note: The actual link may be private due to security concerns)

The Chromium project has not released full exploit details to protect users. However, the code snippet shown previously demonstrates a simple example of how this use-after-free issue might occur.

Fixes and Mitigation

To address the use-after-free vulnerability in Blink Task Scheduling, Google has released a stable channel update for Chrome that contains the necessary security fixes. The affected users must update their Chrome browser to version 115..579.170 or later, which can be downloaded from the official Google Chrome website (https://www.google.com/chrome/).

Additionally, users should exercise caution when visiting untrusted websites or clicking on suspicious links, as these could lead them to a crafted HTML page designed to exploit the vulnerability.

Conclusion

The CVE-2023-4074 vulnerability is a concerning issue in Chrome prior to 115..579.170, as it not only exposes users to potential heap corruption but also paves the way for remote attacks through malicious HTML pages. Therefore, it is crucial for users to keep their Chrome installations up-to-date and follow safe browsing practices to minimize the risk of exploitation.

Timeline

Published on: 08/03/2023 01:15:00 UTC
Last modified on: 08/12/2023 06:21:00 UTC