CVE-2024-26468 is a DOM-based cross-site scripting (XSS) vulnerability discovered in the component index.html of jstrieb/urlpages before commit 035b647. This vulnerability allows attackers to execute arbitrary Javascript code by sending a crafted URL to the victim. In this post, we will provide an in-depth analysis of the vulnerability, discuss its potential impacts, present a code snippet that demonstrates the issue, and provide links to original references and exploit details.

Overview of CVE-2024-26468

Before diving into the technical details of this vulnerability, it is essential to understand what DOM-based XSS is. DOM-based XSS is a type of cross-site scripting where the vulnerability resides in the client-side scripts rather than the server-side code. The attacker injects a payload into the Document Object Model (DOM), which is then executed by the victim's browser.

In the context of CVE-2024-26468, the vulnerability resides in the index.html component of the jstrieb/urlpages project, which is a utility to create single-page websites stored entirely within the URL. The issue allows an attacker to send a crafted URL containing malicious JavaScript code to an unsuspecting victim, who will unknowingly execute the code upon visiting the URL.

Detailed Analysis of the Vulnerability

In the index.html file of the affected versions of jstrieb/urlpages, user-supplied input is not properly sanitized before it is used within the DOM. As a result, an attacker can inject arbitrary JavaScript code into the DOM through the URL, resulting in the execution of the injected code. The following code snippet demonstrates the vulnerability:

<!DOCTYPE html>
<html>
<head>
...
</head>
<body>
...
<script>
    function onloadFunction() {
        let urlString = window.location.href;
        let url = new URL(urlString);
        let content = url.searchParams.get('content');
        if (content) {
            let decodedContent = atob(content);
            document.getElementById('content').innerHTML = decodedContent;
        }
    }
</script>
...
</body>
</html>

In the code above, the function onloadFunction is triggered when the page is loaded. The function retrieves the value of the 'content' parameter from the URL, decodes it using the atob function, and injects the decoded content into the DOM using innerHTML. As there is no validation on the content parameter, an attacker can craft a URL with malicious JavaScript to exploit this vulnerability.

Here is an example of a crafted URL that triggers an alert box when visited

http://www.example.com/index.html?content=PHNjcmlwdD5hbGVydCgnWFNTIFZ1bG5lcmFiaWxpdHknKTs8L3NjcmlwdD4=

With this vulnerability, an attacker can

1. Steal sensitive information, such as user credentials, by injecting malicious code that captures user input (e.g., a fake login form).

Original References

1. CVE-2024-26468 - NVD Detail
2. jstrieb/urlpages GitHub repository
3. jstrieb/urlpages - commit 035b647

Mitigation

The vulnerability in jstrieb/urlpages was fixed in commit 035b647. The fix includes properly sanitizing the user-supplied input before assigning it to the DOM using .innerText instead of .innerHTML. It is strongly recommended to update the jstrieb/urlpages project to the latest version, which includes this crucial security fix.

Conclusion

CVE-2024-26468 highlights the importance of validating and sanitizing user input in web applications irrespective of whether it is server-side or client-side code. By understanding the details of this vulnerability, developers can work to prevent similar occurrences in their own applications and stay better prepared to guard against such attacks. Always ensure to use the latest versions of any libraries and frameworks, and keep up to date with security advisories and best practices for web development.

Timeline

Published on: 02/26/2024 16:27:59 UTC
Last modified on: 02/26/2024 16:32:25 UTC