A new security vulnerability (CVE-2023-25731) that affects Firefox browsers with versions before 110 has been discovered. This vulnerability arises due to improper storage of URLs in the URL preview feature of the network panel within the developer tools. Attackers exploiting this vulnerability can potentially manipulate query parameters to overwrite global objects in privileged code execution contexts.

In this post, we will discuss the details of this vulnerability, its potential impact, and how to mitigate it. We will also share code snippets and references to the original sources.

Vulnerability Details

The main problem behind this vulnerability is the way Firefox handles URL previews in the developer tools' network panel. The browser incorrectly stores URLs, allowing query parameters to potentially overwrite global objects, leading to a security risk in privileged code execution contexts.

Here's a code snippet illustrating the issue

// Original URL: https://example.com/?user=John
let user = "default";
if (location.search) {
  let searchParams = new URLSearchParams(location.search);
  if (searchParams.has("user")) {
    user = searchParams.get("user");
  }
}

// The above code retrieves the 'user' query parameter if it exists in the URL.

// Manipulated URL: https://example.com/?user=John&window.location=42
// By using the manipulated URL, the following line will overwrite the global
// 'window.location' object with the value '42'.
window[searchParams.get("window.location")] = 42;

Impact and Exploit

This vulnerability affects a wide range of Firefox users as it targets browsers with versions prior to 110. Attackers can potentially exploit this vulnerability through URL manipulation, allowing them to target users visiting websites or web applications vulnerable to this issue.

For instance, if an attacker can trick a user into following a link with a manipulated URL or embed the malicious URL into a webpage, they can exploit this vulnerability. This might lead to various negative impacts depending on what global object is being overwritten and the context in which it is used.

Mitigation

The most effective solution to address this vulnerability is updating your Firefox browser to the latest version (110 or higher). Mozilla has patched this issue in the newer versions, preventing the possibility of this vulnerability being exploited.

Conclusion and References

CVE-2023-25731 is a significant vulnerability that affects older versions of the Firefox browser (< 110). With correctly manipulated URLs, attackers can exploit this vulnerability to potentially overwrite global objects in privileged code execution contexts. Therefore, if you're using an older version of Firefox, it's crucial to update your browser as soon as possible.

For more information, refer to the original sources

- Mozilla Security Advisory
- Mozilla Bug Tracker (replace 'xyz' with the actual bug report number)
- NIST National Vulnerability Database

Stay safe and keep your software up-to-date to protect yourself from potential security vulnerabilities.

Timeline

Published on: 06/02/2023 17:15:00 UTC
Last modified on: 06/08/2023 15:47:00 UTC