Executive Summary

The Easy PHP Settings plugin for WordPress, up to version 1.0.4, is vulnerable to PHP Code Injection via the update_wp_memory_constants() method.

This vulnerability arises because the plugin does not properly validate the wp_memory_limit and wp_max_memory_limit settings before writing them to the wp-config.php file.

The sanitization function used, sanitize_text_field(), does not filter out single quotes, which allows an attacker with Administrator-level access to break out of the string context in a PHP define() statement.

As a result, an authenticated attacker can inject and execute arbitrary PHP code on the server by modifying the wp-config.php file, which is loaded on every page request.

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Impact Analysis

This vulnerability allows an attacker with Administrator-level access to execute arbitrary PHP code on the server.

Such code execution can lead to full compromise of the WordPress site and potentially the underlying server.

The attacker can modify the wp-config.php file, which is loaded on every page request, enabling persistent malicious code execution.

This can result in data theft, site defacement, unauthorized access, or use of the server for malicious activities.

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Compliance Impact

I don't know

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Detection Guidance

[{'type': 'paragraph', 'content': 'This vulnerability involves PHP code injection via the Easy PHP Settings WordPress plugin versions up to 1.0.4, specifically through the `update_wp_memory_constants()` method that improperly sanitizes `wp_memory_limit` and `wp_max_memory_limit` settings.'}, {'type': 'paragraph', 'content': 'Detection on your system can focus on checking if the vulnerable plugin version (<= 1.0.4) is installed and active on your WordPress site.'}, {'type': 'paragraph', 'content': 'You can also inspect the `wp-config.php` file for unexpected or suspicious PHP code injections, especially around the definitions of memory limits.'}, {'type': 'list_item', 'content': "Check the plugin version installed: Use WP-CLI command `wp plugin list` to verify if 'easy-php-settings' plugin is installed and its version."}, {'type': 'list_item', 'content': 'Search for suspicious code in wp-config.php: Use command `grep -i \'wp_memory_limit\' wp-config.php` or `grep -P "define\\s*\\(\\s*\'WP_MEMORY_LIMIT\'" wp-config.php` to look for injected PHP code or anomalies.'}, {'type': 'list_item', 'content': 'Audit recent changes to wp-config.php: Use `stat wp-config.php` to check modification times and `diff` with a known good backup to detect unauthorized changes.'}, {'type': 'list_item', 'content': 'Review WordPress admin users with Administrator-level access for suspicious activity, since exploitation requires authenticated admin privileges.'}] [1]

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Mitigation Strategies

Immediate mitigation steps include:

• Update the Easy PHP Settings plugin to version 1.0.5 or later, where this vulnerability has been fixed.
• Restrict Administrator-level access to trusted users only, as exploitation requires authenticated admin privileges.
• Manually review and clean the `wp-config.php` file to remove any injected malicious PHP code.
• Implement monitoring and alerting for changes to critical files like `wp-config.php`.
• Consider temporarily disabling the Easy PHP Settings plugin until the update can be applied.
• Ensure your WordPress installation and all plugins are kept up to date to reduce exposure to known vulnerabilities.

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