OS Command Injection in WP Database Backup Plugin

Executive Summary

The WP Database Backup plugin for WordPress is vulnerable to OS Command Injection through the wp_db_exclude_table parameter in versions up to 7.11. This happens because user input from this parameter is directly concatenated into a mysqldump shell command without proper escaping, unlike other parameters. Although some filtering removes HTML tags, dangerous shell metacharacters remain, allowing an attacker with administrator access to execute arbitrary operating system commands on the server.

The malicious input is stored persistently in the WordPress options table and executed whenever a backup operation runs, potentially enabling full remote code execution.

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Impact Analysis

This vulnerability allows an authenticated attacker with administrator-level access to execute arbitrary operating system commands on the server hosting the WordPress site. This can lead to full remote code execution, compromising the server's security and potentially allowing the attacker to take complete control over the system.

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Compliance Impact

This vulnerability allows authenticated attackers with administrator-level access to execute arbitrary operating system commands on the server, potentially enabling full remote code execution.

Such unauthorized access and control over the server could lead to data breaches, unauthorized data modification, or data loss.

Consequently, this could impact compliance with common standards and regulations like GDPR and HIPAA, which require protection of sensitive data and maintaining system integrity.

However, the provided information does not explicitly detail the compliance implications or specific regulatory impacts.

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Detection Guidance

This vulnerability involves OS command injection via the wp_db_exclude_table parameter in the WP Database Backup plugin. Detection would focus on identifying suspicious or unauthorized use of this parameter, especially in POST requests to the plugin's settings or backup execution endpoints.

Since the injection is stored and executed during backup operations, monitoring for unusual shell commands or unexpected mysqldump executions on the server could help detect exploitation attempts.

• Check WordPress options table for suspicious wp_db_exclude_table values using SQL queries, e.g., `SELECT option_value FROM wp_options WHERE option_name = 'wp_db_exclude_table';`
• Monitor web server logs for POST requests containing the wp_db_exclude_table parameter with shell metacharacters such as `;`, `|`, `` ` ``, or `$()`.
• On the server, search for mysqldump commands executed with unusual arguments by inspecting process lists or command histories, e.g., `ps aux | grep mysqldump`.
• Use file integrity monitoring or audit logs to detect unexpected changes or executions related to the backup plugin.

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Mitigation Strategies

Immediate mitigation steps include restricting access to the plugin settings to only trusted administrators, as exploitation requires administrator-level access.

Temporarily disable or uninstall the WP Database Backup plugin until a patched version is available.

Review and sanitize the wp_db_exclude_table option value in the WordPress database to remove any malicious input.

Apply principle of least privilege to WordPress users and server permissions to limit the impact of potential exploitation.

Monitor server logs and WordPress activity for signs of exploitation and respond accordingly.

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