Security researchers have recently discovered a Cross-site Scripting (XSS) vulnerability, dubbed CVE-2023-4913, in the popular static site generator, Cecil. This vulnerability has been found in the GitHub repository cecilapp/cecil in versions prior to 7.47.1. The affected versions of the software are susceptible to a Reflected XSS attack, allowing malicious actors to successfully execute arbitrary JavaScript code on a victim's browser.

This detailed post will provide an in-depth analysis of the vulnerability CVE-2023-4913, including a code snippet that demonstrates the exploit, links to original references for further understanding, and recommended steps to remediate the security flaw.

Exploit Details

A Reflected XSS vulnerability occurs when an application includes user-supplied data in an HTTP response without properly sanitizing or encoding the input. This flaw allows an attacker to inject malicious JavaScript code into a victim's browser, leading to various potential attacks, such as session hijacking, sensitive data exfiltration, and phishing scams.

In the case of CVE-2023-4913, the vulnerable Cecil code fails to properly validate and sanitize user input on certain URL parameters, causing the Reflected XSS issue.

Code Snippet

The following code snippet demonstrates the exploitation of the vulnerability in a vulnerable version of Cecil:

// Malicious URL
http://vulnerable-website.com/?search=<script>alert('XSS')</script>;

// Vulnerable Cecil Code
function getSearchParameter() {
  var urlParams = new URLSearchParams(window.location.search);
  return urlParams.get('search');
}

function showSearchResults() {
  var searchQuery = getSearchParameter();
  if (searchQuery) {
    var resultElement = document.getElementById('search-results');
    
    // Reflected XSS occurs here:
    resultElement.innerHTML = 'Search results for: ' + searchQuery;
  }
}

In this code snippet, the getSearchParameter function extracts the "search" parameter from the URL without sanitizing the input. Afterwards, the showSearchResults function directly injects the unsanitized user input into the HTML document using element.innerHTML, leading to a successful XSS attack.

Original References

1. CVE-2023-4913 NVD Entry
2. Cecil GitHub Repository
3. Cecil Changelog for 7.47.1

Remediation Steps

Users running affected versions of Cecil are strongly advised to update to the latest version (7.47.1 or higher) to patch the vulnerability. The Cecil team has addressed and released a fix for the vulnerability in the aforementioned version.

To update Cecil, run the following command

composer update cecil/cecil

Additionally, developers should practice secure coding principles when handling user input, including proper input validation, sanitization, and output encoding to mitigate the risk of XSS vulnerabilities. For further guidance on secure coding practices, refer to resources such as the OWASP Top Ten Project and the OWASP Cheat Sheet Series.

Timeline

Published on: 09/12/2023 15:15:00 UTC
Last modified on: 09/14/2023 00:44:00 UTC