CVE-2024-11015: Sign In With Google Auth Bypass Flaw

CVE-2024-11015 Overview

The Sign In With Google plugin for WordPress contains a critical authentication bypass vulnerability affecting all versions up to and including 1.8.0. The vulnerability exists in the authenticate_user function due to insufficient null value checks when setting the access token and user information during Google OAuth authentication. This flaw allows unauthenticated attackers to bypass authentication and log in as the first user who has signed in using Google OAuth, which is often the site administrator.

Critical Impact

Unauthenticated attackers can gain administrative access to WordPress sites by exploiting insufficient null value validation in the Google OAuth authentication flow, potentially leading to complete site compromise.

Affected Products

• Sign In With Google plugin for WordPress version 1.8.0 and earlier
• WordPress sites using Google OAuth authentication via this plugin
• Sites where administrators use Google OAuth as their primary login method

Discovery Timeline

• 2024-12-12 - CVE-2024-11015 published to NVD
• 2024-12-12 - Last updated in NVD database

Technical Details for CVE-2024-11015

Vulnerability Analysis

This authentication bypass vulnerability (CWE-287) stems from improper validation in the OAuth authentication flow. The authenticate_user function in the Sign In With Google plugin fails to implement sufficient null value checks when processing access tokens and user information received during the Google OAuth process. When these critical values are null or improperly validated, the authentication logic can be manipulated to grant access to existing user accounts.

The attack surface is particularly dangerous because the first Google OAuth user is often the site administrator who initially configured the plugin. An attacker exploiting this vulnerability could gain full administrative privileges without any prior authentication, enabling complete site takeover including the ability to inject malicious code, steal sensitive data, or pivot to attack other systems.

Root Cause

The root cause lies in the authenticate_user function located in class-sign-in-with-google-admin.php. The function does not properly validate null values when processing:

1. The access token returned from Google's OAuth service
2. User information retrieved using that access token
3. The association between the OAuth identity and existing WordPress user accounts

This insufficient validation creates a condition where the authentication flow can proceed without proper verification of the user's identity, defaulting to the first OAuth-registered user.

Attack Vector

The vulnerability is exploitable over the network without requiring any authentication or user interaction. An attacker can craft malicious OAuth callback requests that exploit the null value handling weakness. By sending requests with carefully manipulated parameters to the OAuth callback endpoint, an attacker can trigger the vulnerable code path that bypasses the normal authentication checks.

The attack flow involves:

1. Identifying a WordPress site using the vulnerable Sign In With Google plugin
2. Initiating a crafted OAuth authentication request
3. Manipulating the callback parameters to exploit the null value validation weakness
4. Gaining access as the first Google OAuth user (typically the administrator)

Technical details of the vulnerable code can be reviewed in the WordPress Plugin Code Review.

Detection Methods for CVE-2024-11015

Indicators of Compromise

• Unexpected administrator login sessions, especially from unfamiliar IP addresses or geolocations
• Authentication logs showing successful Google OAuth logins without corresponding legitimate user activity
• WordPress activity logs indicating administrative actions performed at unusual times or by unexpected accounts
• Multiple failed OAuth callback requests followed by a successful authentication

Detection Strategies

• Monitor WordPress authentication logs for OAuth callback requests with anomalous parameters or null values
• Implement Web Application Firewall (WAF) rules to detect and block malformed OAuth callback requests
• Review access logs for patterns of authentication bypass attempts targeting the Google OAuth endpoints
• Deploy integrity monitoring on WordPress core files and plugin directories to detect post-compromise modifications

Monitoring Recommendations

• Enable detailed logging for the Sign In With Google plugin authentication events
• Configure alerts for administrative account logins, especially outside normal business hours
• Monitor for new user account creation or privilege escalation following OAuth authentication events
• Implement real-time alerting on WordPress admin panel access from previously unseen IP addresses

How to Mitigate CVE-2024-11015

Immediate Actions Required

• Update the Sign In With Google plugin to a version newer than 1.8.0 immediately
• Review WordPress user accounts and sessions for any unauthorized administrative access
• Audit recent administrative actions for signs of compromise
• Consider temporarily disabling Google OAuth authentication until the patch is applied
• Reset sessions for all administrator accounts as a precautionary measure

Patch Information

Site administrators should update the Sign In With Google plugin through the WordPress admin dashboard or by downloading the latest version from the WordPress plugin repository. The update addresses the null value validation weakness in the authenticate_user function. Additional details are available in the Wordfence Vulnerability Report.

Workarounds

• Disable the Sign In With Google plugin entirely until an update can be applied
• Implement additional authentication layers such as two-factor authentication for administrator accounts
• Restrict access to the WordPress admin panel by IP address using .htaccess or firewall rules
• Use a Web Application Firewall to filter malicious OAuth callback requests
• Ensure alternative login methods are available and functional before disabling OAuth

# Temporarily disable the Sign In With Google plugin via WP-CLI
wp plugin deactivate sign-in-with-google

# After updating, re-enable with
wp plugin activate sign-in-with-google

# Verify the installed version is patched
wp plugin list --name=sign-in-with-google --fields=name,version,status