CVE-2024-35661: WPForms Upload Fields Auth Bypass Flaw

CVE-2024-35661 Overview

CVE-2024-35661 is a Missing Authorization vulnerability affecting the Upload Fields for WPForms plugin developed by SoftLab. This WordPress plugin extends WPForms functionality by allowing file upload fields, but versions through 1.0.2 contain a broken access control flaw that allows unauthorized users to perform privileged actions without proper authentication or authorization checks.

Critical Impact

This vulnerability allows unauthenticated attackers to bypass authorization controls, potentially gaining unauthorized access to sensitive upload functionality and data within WordPress sites using the affected plugin.

Affected Products

• SoftLabBD Upload Fields for WPForms versions through 1.0.2
• WordPress installations using the affected plugin versions
• Sites with WPForms configured with upload field functionality

Discovery Timeline

• 2024-06-09 - CVE-2024-35661 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2024-35661

Vulnerability Analysis

This vulnerability falls under CWE-862: Missing Authorization, indicating that the plugin fails to properly verify that a user has the required permissions before allowing access to certain functions or resources. In WordPress plugins, this typically manifests when AJAX handlers, REST API endpoints, or form processing functions neglect to implement capability checks using functions like current_user_can() or nonce verification.

The Upload Fields for WPForms plugin provides file upload capabilities that extend the base WPForms functionality. When authorization checks are missing, attackers can potentially manipulate upload operations, access uploaded files, or invoke privileged administrative functions without proper authentication.

Root Cause

The root cause is the absence of proper authorization verification in one or more functions within the plugin. WordPress plugins should implement capability checks to ensure that only users with appropriate roles can access sensitive functionality. The plugin fails to validate user permissions before executing operations related to file uploads or plugin settings, leaving these functions accessible to unauthenticated or low-privileged users.

Attack Vector

The vulnerability is exploitable over the network without requiring authentication or user interaction. An attacker can directly send crafted requests to vulnerable endpoints exposed by the plugin. Since no privileges are required, any remote attacker with network access to a WordPress site running the vulnerable plugin can potentially exploit this flaw.

Exploitation typically involves:

1. Identifying AJAX actions or REST endpoints exposed by the plugin
2. Crafting HTTP requests that bypass non-existent authorization checks
3. Executing privileged operations such as file manipulation or configuration changes
4. Potentially escalating access to the broader WordPress installation

Detection Methods for CVE-2024-35661

Indicators of Compromise

• Unexpected AJAX requests to WordPress admin-ajax.php targeting Upload Fields for WPForms actions
• Unusual file upload activity or unauthorized file access in wp-content/uploads directories
• Log entries showing unauthenticated access attempts to plugin-specific endpoints
• Modifications to plugin settings without corresponding administrative activity

Detection Strategies

• Monitor web server logs for POST requests to admin-ajax.php with actions related to the Upload Fields for WPForms plugin
• Implement Web Application Firewall (WAF) rules to detect and block requests attempting to access plugin functions without valid authentication cookies
• Review WordPress access logs for patterns of unauthenticated requests targeting plugin-specific endpoints
• Enable audit logging for file system changes in WordPress upload directories

Monitoring Recommendations

• Deploy endpoint detection solutions that can identify suspicious WordPress plugin activity
• Configure alerts for unusual HTTP request patterns targeting admin-ajax.php with upload-related actions
• Monitor for new or modified files in WordPress upload directories that don't correspond to legitimate user activity
• Implement integrity monitoring for plugin files to detect unauthorized modifications

How to Mitigate CVE-2024-35661

Immediate Actions Required

• Update Upload Fields for WPForms to a version newer than 1.0.2 if a patched version is available
• Temporarily disable the Upload Fields for WPForms plugin until a fix is applied
• Review site access logs for signs of exploitation
• Audit any files uploaded through WPForms for malicious content

Patch Information

Organizations should check the WordPress plugin repository and the Patchstack Vulnerability Report for the latest patch status. The vulnerability affects versions through 1.0.2, so ensure your installation is updated to a version that includes the authorization fix.

Workarounds

• Temporarily deactivate the Upload Fields for WPForms plugin if updates are not immediately available
• Implement WAF rules to restrict access to plugin AJAX handlers and require authentication
• Limit file upload functionality to authenticated users only through WordPress user management
• Consider using alternative file upload plugins with verified security practices until this vulnerability is resolved

# Disable the plugin via WP-CLI
wp plugin deactivate upload-fields-for-wpforms

# Check current plugin version
wp plugin list --name=upload-fields-for-wpforms --fields=name,version,status

# Update plugin if patch is available
wp plugin update upload-fields-for-wpforms