In this post, we will dive deep into the details of the CVE-2024-3834 vulnerability that affects Google Chrome versions prior to 124..6367.60. This use-after-free vulnerability in the Downloads module of Chrome could potentially allow a remote attacker to exploit heap corruption via a maliciously crafted HTML page.

Use-After-Free Vulnerabilities: An Overview

A use-after-free vulnerability occurs when a program continues to use a pointer after the memory it points to has been freed and potentially reallocated. This can lead to a variety of security issues, including arbitrary code execution, data corruption, denial-of-service (DoS) attacks, and more. These types of vulnerabilities are especially dangerous because attackers can often exploit them by crafting malicious input that triggers the vulnerability.

The Vulnerability in Google Chrome

This particular vulnerability, identified as CVE-2024-3834, has been found in the Downloads module of Google Chrome versions prior to 124..6367.60. The chromium team has assigned this vulnerability a security severity rating of "High", indicating that it exposes impacted systems to significant risk if left unpatched.

Code Snippet: The Vulnerable Function

The vulnerability occurs because of an improper implementation of an internal function, which results in a use-after-free situation. The following code snippet showcases a simplified version of the vulnerable function:

void DownloadItem::OnDownloadUpdated() {
  // ...

  if (download_->IsComplete()) {
    // Do something...
  } else {
    // ...

    // The bug: We free the memory here...
    delete download_;

    // The use-after-free: We access the freed memory here.
    if (download_->IsCancelled()) {
      // Do something...
    }
  }

  // ...
}

As you can see, the function frees the download_ pointer and then, mistakenly, accesses it later, causing a use-after-free vulnerability.

Exploiting the Vulnerability

An attacker could exploit this vulnerability by creating a malicious HTML page containing a crafted payload designed to exploit the use-after-free vulnerability in the Downloads code. As an example, the attacker could create an HTML page with a hidden iframe that triggers multiple downloads, causing the vulnerable function to execute and, with the right payload, potentially exploit heap corruption in the victim's Chrome browser.

Original References

- Google Chromium Security Team's Announcement: Chrome Releases: Stable Channel Update for Desktop
- NVD Vulnerability Details: CVE-2024-3834
- Chromium Bug Tracker: Issue 1316739: UaF in downloads

Mitigating the Risk

To mitigate the risk associated with this vulnerability, it is essential to keep your Google Chrome browser up to date. Users should make sure they are running Google Chrome version 124..6367.60 or later, which includes a fix for the vulnerability. To check your current version and update if necessary, follow these steps:

Select "Help" > "About Google Chrome."

4. The browser will automatically check for updates and provide you with the option to update if a newer version is available.

In conclusion, the CVE-2024-3834 vulnerability presents a considerable risk to users of Google Chrome. By understanding the details of this use-after-free vulnerability and taking appropriate steps to protect your systems through timely updates, you can help safeguard your devices and information from potential exploitation.

Timeline

Published on: 04/17/2024 08:15:10 UTC
Last modified on: 05/03/2024 04:15:09 UTC