CVE-2024-31352: Email Subscribers Auth Bypass Flaw

CVE-2024-31352 Overview

CVE-2024-31352 is a Missing Authorization vulnerability affecting the Icegram Email Subscribers & Newsletters plugin for WordPress. This broken access control flaw allows unauthenticated attackers to perform unauthorized actions that should require administrative privileges. The vulnerability exists due to improper authorization checks on sensitive functionality within the plugin, enabling remote attackers to bypass security restrictions without any authentication.

Critical Impact

This vulnerability allows unauthenticated remote attackers to bypass authorization controls, potentially leading to complete compromise of confidentiality, integrity, and availability of the affected WordPress installation.

Affected Products

• Icegram Email Subscribers & Newsletters versions up to and including 5.7.13
• WordPress installations running vulnerable versions of the plugin

Discovery Timeline

• 2024-06-09 - CVE-2024-31352 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2024-31352

Vulnerability Analysis

This vulnerability is classified as CWE-862 (Missing Authorization), a broken access control weakness where the application fails to verify whether a user has proper authorization before allowing access to restricted functionality. In the context of the Icegram Email Subscribers & Newsletters plugin, certain administrative functions lack proper capability checks, allowing unauthenticated users to invoke privileged operations.

The vulnerability impacts WordPress sites by exposing administrative plugin functionality to external attackers. Without proper nonce verification or capability checks on AJAX handlers or REST API endpoints, attackers can manipulate subscriber data, export sensitive information, or modify plugin configurations remotely.

Root Cause

The root cause of CVE-2024-31352 lies in insufficient authorization verification within the Icegram Email Subscribers & Newsletters plugin. WordPress plugins typically implement access control through capability checks using functions like current_user_can() combined with nonce verification to prevent unauthorized access. When these checks are missing or improperly implemented, any user—including unauthenticated visitors—can trigger sensitive operations.

The affected plugin versions (through 5.7.13) fail to properly validate user permissions before executing privileged functionality, creating a direct path for exploitation without requiring authentication.

Attack Vector

The attack vector for this vulnerability is network-based, requiring no user interaction or prior authentication. An attacker can exploit this flaw by sending specially crafted HTTP requests directly to the vulnerable WordPress endpoints.

The exploitation flow typically involves:

1. Identifying WordPress installations running the vulnerable Email Subscribers & Newsletters plugin
2. Discovering exposed endpoints or AJAX actions lacking authorization checks
3. Crafting malicious requests to invoke privileged functionality
4. Executing unauthorized operations such as data exfiltration, subscriber manipulation, or configuration changes

Technical details and specific exploitation methods are documented in the Patchstack Vulnerability Advisory.

Detection Methods for CVE-2024-31352

Indicators of Compromise

• Unexpected modifications to email subscriber lists or newsletter configurations
• Unusual HTTP requests to WordPress AJAX endpoints (admin-ajax.php) referencing Email Subscribers actions
• Unauthorized export or deletion of subscriber data
• Anomalous activity in WordPress audit logs related to the Email Subscribers plugin

Detection Strategies

• Monitor web server access logs for suspicious requests to admin-ajax.php with Email Subscribers-related action parameters
• Implement Web Application Firewall (WAF) rules to detect and block unauthorized access attempts to plugin endpoints
• Deploy WordPress security plugins that audit capability check failures and unauthorized API access
• Review plugin activity logs for operations performed without proper user authentication

Monitoring Recommendations

• Enable comprehensive logging for all WordPress AJAX and REST API requests
• Set up alerts for bulk subscriber data exports or modifications outside normal operational hours
• Monitor for rapid sequential requests targeting Email Subscribers functionality from single IP addresses
• Implement real-time file integrity monitoring on the Email Subscribers plugin directory

How to Mitigate CVE-2024-31352

Immediate Actions Required

• Update the Icegram Email Subscribers & Newsletters plugin to the latest patched version immediately
• Audit subscriber data and plugin configurations for unauthorized modifications
• Review web server logs for evidence of exploitation attempts
• Temporarily disable the plugin if an update is not immediately available
• Implement IP-based access restrictions for WordPress administrative functions

Patch Information

Organizations should update the Icegram Email Subscribers & Newsletters plugin beyond version 5.7.13 to remediate this vulnerability. The patch addresses the missing authorization checks by implementing proper capability verification before executing privileged operations.

For detailed patch information and upgrade instructions, refer to the Patchstack Vulnerability Advisory.

Workarounds

• Deploy a Web Application Firewall (WAF) with rules to block unauthorized requests to Email Subscribers plugin endpoints
• Restrict access to admin-ajax.php using server-level configurations for non-authenticated users where feasible
• Implement network-level access controls to limit administrative endpoint access to trusted IP ranges
• Use WordPress security hardening plugins to add additional authorization layers

# Apache .htaccess example to restrict admin-ajax.php access patterns
# Add to WordPress root .htaccess - adjust for your environment
<Files admin-ajax.php>
    <RequireAll>
        Require all granted
    </RequireAll>
</Files>

# Consider implementing rate limiting at the server level
# Example for nginx (add to server block):
# limit_req_zone $binary_remote_addr zone=ajax:10m rate=10r/s;
# location = /wp-admin/admin-ajax.php {
#     limit_req zone=ajax burst=20 nodelay;
# }