How to remediate – WordPress Administration Panel Login Form Bruteforced

1. Introduction

The WordPress Administration Panel Login Form Bruteforced vulnerability occurs when an attacker attempts multiple login combinations on a WordPress site’s admin panel. This can succeed if accounts use weak or easily guessed passwords. Successful exploitation allows attackers to gain complete control of the website, potentially leading to data theft, defacement, and malware installation. Confidentiality, integrity, and availability are all at risk.

2. Technical Explanation

This vulnerability happens because the WordPress login form doesn’t adequately protect against repeated attempts with different credentials. An attacker can use automated tools to try many username/password pairs until a valid combination is found. The preconditions for exploitation are an accessible WordPress administration panel and accounts with weak or default passwords. Common Web Application Firewalls (WAFs) may not block this type of attack without specific rules.

• Root cause: Insufficient rate limiting on login attempts, allowing attackers to try numerous credentials.
• Exploit mechanism: An attacker uses a script or tool like Hydra or WP-BruteForce to send many login requests to the /wp-login.php endpoint.
• Scope: All WordPress installations with publicly accessible admin panels are affected, especially those using default usernames (like ‘admin’) and weak passwords.

3. Detection and Assessment

You can check for this vulnerability by verifying the password policy on your WordPress installation. Thorough assessment involves monitoring login attempts in server logs.

• Quick checks: Check the WordPress admin panel settings under Users > Profile to see if users have strong passwords.
• Scanning: Nessus plugin 16894 and OpenVAS scan ID 935702 can identify weak credentials or missing rate limiting. These are examples only, results may vary.
• Logs and evidence: Examine web server logs (e.g., Apache access logs) for repeated failed login attempts to /wp-login.php from the same IP address. Look for HTTP status codes 200 following multiple 403 errors.

grep "/wp-login.php" /var/log/apache2/access.log | awk '{print $1}' | sort | uniq -c | sort -nr

4. Solution / Remediation Steps

The following steps will help to secure your WordPress installation against brute force attacks.

4.1 Preparation

• No services need to be stopped for these changes, but it’s best practice to perform them during off-peak hours.

4.2 Implementation

1. Step 1: Change the default username ‘admin’. Create a new administrator account with a strong, unique username.
2. Step 2: Enforce a complex password policy for all users in WordPress settings (Users > Profile Settings). Require minimum length and character diversity.
3. Step 3: Install a brute force protection plugin from the official WordPress repository (see section 4.5).
4. Step 4: Limit login attempts using a plugin or server-side configuration (e.g., fail2ban).

4.3 Config or Code Example

Before

/* No password complexity enforced */

After

define( 'WP_PASSWORD_POLICY', true ); /* Enforce strong passwords */
define( 'WP_PASSWORD_MIN_LENGTH', 12 ); /* Minimum password length */

4.4 Security Practices Relevant to This Vulnerability

Several security practices can help prevent brute force attacks.

• Least privilege: Limit the number of administrator accounts and grant only necessary permissions.
• Strong passwords: Require complex, unique passwords for all users.
• Input validation: While not directly applicable to login attempts, validate other user inputs to prevent injection attacks that could bypass authentication.

4.5 Automation (Optional)

You can automate the installation of a brute force protection plugin using WP-CLI.

wp plugin install limit-login-attempts --activate

5. Verification / Validation

Confirm the fix by testing the password policy and verifying that login attempts are limited.

• Post-fix check: Check WordPress settings (Users > Profile Settings) to confirm the complex password policy is enabled.
• Smoke test: Verify that legitimate users can still log in successfully with their correct credentials.
• Monitoring: Monitor web server logs for blocked login attempts, indicating the brute force protection is working. Example query: grep "Login attempt failed" /var/log/apache2/error.log.

wp user list | grep -c 'administrator' # Confirm only necessary admin accounts exist.

6. Preventive Measures and Monitoring

Regularly review your WordPress security configuration and monitor for suspicious activity.

• Baselines: Implement a CIS benchmark or similar security baseline for WordPress to ensure consistent settings.
• Pipelines: Use SAST tools during development to identify weak passwords in code or configuration files.
• Asset and patch process: Review and apply WordPress core updates and plugin updates promptly to address known vulnerabilities. A monthly review cycle is recommended.

7. Risks, Side Effects, and Roll Back

Changing the password policy may require users to reset their passwords, causing temporary inconvenience. Incorrect configuration of brute force protection could lock out legitimate users.

• Risk or side effect 1: Users may forget new passwords if a complex policy is enforced. Provide clear instructions for password recovery.
• Risk or side effect 2: Overly aggressive brute force protection can block legitimate users. Monitor logs and adjust settings as needed.
• Roll back: Restore the database from backup to revert to the previous configuration. Deactivate any installed plugins if necessary.

8. References and Resources

Links to relevant resources for this vulnerability.

• Vendor advisory or bulletin: https://wordpress.org/
• NVD or CVE entry: No specific CVE is associated with generic brute force attacks, but related vulnerabilities are documented on the NVD website.
• Product or platform documentation relevant to the fix: https://wordpress.org/plugins/tags/brute-force/