CVE-2024-3495: WordPress CF7 Plugin SQLi Vulnerability

CVE-2024-3495 Overview

The Country State City Dropdown CF7 plugin for WordPress contains a critical SQL Injection vulnerability affecting versions up to and including 2.7.2. The vulnerability exists due to insufficient escaping on user-supplied parameters and a lack of sufficient preparation on existing SQL queries. This security flaw allows unauthenticated attackers to inject malicious SQL queries through the cnt and sid parameters, enabling extraction of sensitive information from the WordPress database.

Critical Impact

Unauthenticated attackers can exploit this SQL Injection vulnerability to extract sensitive data from the database, potentially compromising user credentials, personal information, and other confidential data stored in WordPress installations using this plugin.

Affected Products

• Country State City Dropdown CF7 plugin for WordPress versions ≤ 2.7.2
• WordPress installations with the vulnerable plugin active
• Contact Form 7 integrations using the affected dropdown functionality

Discovery Timeline

• 2024-05-22 - CVE-2024-3495 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2024-3495

Vulnerability Analysis

This SQL Injection vulnerability stems from improper input handling in the plugin's AJAX action handlers. The vulnerable code resides in the ajax-actions.php file where user-supplied parameters are directly incorporated into SQL queries without proper sanitization or parameterized queries.

The plugin processes location-based dropdown selections through AJAX endpoints, accepting cnt (country) and sid (state ID) parameters. These parameters are expected to contain identifiers for cascading dropdown functionality but fail to properly validate or escape the input before using it in database queries. This allows attackers to append arbitrary SQL statements to existing queries.

The vulnerability is particularly severe because it can be exploited by unauthenticated users. Since the AJAX endpoints are publicly accessible to generate dropdown options, any visitor to a website using this plugin can potentially exploit this flaw.

Root Cause

The root cause of this vulnerability is the failure to implement proper input sanitization and parameterized queries (prepared statements) when handling user-supplied data. The cnt and sid parameters are passed directly into SQL queries without using WordPress's $wpdb->prepare() function or equivalent escaping mechanisms.

WordPress provides built-in database abstraction methods that prevent SQL injection when used correctly. The vulnerable code bypasses these protections by concatenating user input directly into query strings, a classic anti-pattern that leads to SQL Injection vulnerabilities.

Attack Vector

The attack can be executed remotely over the network without authentication. An attacker can craft malicious HTTP requests to the WordPress AJAX handler (admin-ajax.php) with specially crafted cnt or sid parameter values containing SQL injection payloads.

A typical attack scenario involves sending requests to the site's AJAX endpoint with SQL injection payloads designed to manipulate the query logic. Techniques such as UNION-based injection can be used to extract data from other tables, including the wp_users table containing usernames and password hashes.

For technical details on the vulnerable code patterns, see the WordPress Plugin Code Review and the Wordfence Vulnerability Report.

Detection Methods for CVE-2024-3495

Indicators of Compromise

• Unusual database queries in WordPress debug logs containing SQL syntax or UNION statements
• Anomalous requests to admin-ajax.php with suspicious cnt or sid parameter values
• Unexpected data exfiltration patterns in web server access logs
• Database error messages appearing in response to form interactions

Detection Strategies

• Monitor web server logs for requests containing SQL keywords (UNION, SELECT, OR 1=1) in the cnt or sid parameters
• Implement Web Application Firewall (WAF) rules to detect and block SQL injection attempts targeting AJAX endpoints
• Deploy database activity monitoring to identify unusual query patterns or unauthorized data access
• Utilize SentinelOne's Singularity XDR platform to detect exploitation attempts and anomalous behavior patterns

Monitoring Recommendations

• Enable WordPress debug logging to capture database errors that may indicate exploitation attempts
• Configure alerts for high-volume requests to admin-ajax.php with action= parameters related to the country-state-city plugin
• Implement regular database integrity checks to detect unauthorized modifications
• Monitor for signs of data exfiltration such as unusually large response sizes from AJAX endpoints

How to Mitigate CVE-2024-3495

Immediate Actions Required

• Update the Country State City Dropdown CF7 plugin to the latest patched version immediately
• Review web server logs for any signs of prior exploitation attempts
• If exploitation is suspected, perform a full database audit and consider resetting all user credentials
• Temporarily disable the plugin if an immediate update is not possible

Patch Information

The vulnerability has been addressed in versions after 2.7.2. Security patches implementing proper input sanitization and prepared statements have been released. Review the WordPress Plugin Changeset History for detailed information about the security fixes applied.

Workarounds

• Deploy a Web Application Firewall (WAF) with SQL injection protection rules enabled
• Implement server-level input validation to filter malicious characters from the cnt and sid parameters
• Restrict access to admin-ajax.php from untrusted IP ranges if feasible for your deployment
• Consider using a security plugin like Wordfence to add an additional layer of protection while awaiting patch deployment

# Example .htaccess rule to block suspicious requests (temporary mitigation)
# Add to WordPress root .htaccess file
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteCond %{QUERY_STRING} (union|select|insert|drop|delete|update|concat|load_file) [NC]
RewriteRule ^wp-admin/admin-ajax\.php$ - [F,L]
</IfModule>