Understanding the Differences Between LOAD DATA INFILE and LOAD DATA "LOCAL" INFILE in MySQL and MariaDB: Security Considerations for DBAs

In MySQL and MariaDB, the commands LOAD DATA INFILE and LOAD DATA LOCAL INFILE efficiently load data from external files into database tables. While they may appear similar at first glance, they operate under different conditions and involve distinct security implications that database administrators (DBAs) must carefully consider. This blog post explores these differences and highlights the critical security aspects associated with each command.

LOAD DATA INFILE: Loading Files from the Database Server

The LOAD DATA INFILE command loads data from a file placed on the database server.

Here’s how it works and what DBAs need to know:

• File Location: The file must reside on the database server, and the path to this file must adhere to the restrictions defined by the MySQL variable @@global.secure_file_priv. This variable sets a secure directory where MySQL and MariaDB can access files, preventing unauthorized access across the system;
• User Privileges: To execute this command, the user must have the FILE privilege granted. This is an admin-level privilege because it allows the user to read any file from the server, which can pose a significant security risk if not adequately controlled.

This command is typically used in environments where the DBA has complete control over the server and can enforce strict access controls. It’s often employed in automated data-loading processes within a secured server environment.

LOAD DATA LOCAL INFILE: Loading Files from the Client Server

The LOAD DATA LOCAL INFILE command is designed to load data from a file located on the client’s server rather than the database server.

Here are the key aspects:

• File Location: Unlike LOAD DATA INFILE, the file is on the client’s machine. This makes the command more flexible but also introduces additional security considerations.
• User Privileges: The user executing this command does not need the FILE privilege. The file is being read from the client side, not the server.
• MySQL Server Configuration: For this command to work, the MySQL server must be explicitly configured to allow it. This is done by setting the @@global.local_infile variable to 1. However, this setting is disabled by default due to the security risks it presents.

This command is helpful in scenarios where data needs to be loaded from remote clients, especially in distributed environments. However, due to its security risks, it should be used sparingly and with caution. The recommendation is to keep that disabled.

General Security Best Practices for Using LOAD DATA Commands

Given the robust nature of LOAD DATA INFILE and LOAD DATA LOCAL INFILE, DBAs must implement stringent security measures to protect the database environment.

Here are some best practices:

• Privilege Management: Limit the FILE privilege to only those users who absolutely need it. Don't grant the FILE privilege to non-administrative users. Regularly audit user privileges to ensure compliance with security policies.
• Secure File Paths: Use the secure_file_priv variable to define a specific directory for file operations. This directory should be regularly monitored for unauthorized access or changes and have access configured to DBAs only.
• Encrypt Connections: SSL/TLS is always required for connections, especially when using LOAD DATA LOCAL INFILE. This protects data in transit and ensures only authenticated clients can interact with the database. Remember, TLS certificates identify who is connecting to the database.
• Disable local_infile by Default: Unless there is a specific requirement, disable the @@global.local_infile setting to prevent accidental misuse or exploitation by malicious users.
• Audit and Logging: Enable detailed logging of file operations and SQL commands that load data. This allows for quick identification and response to suspicious activities. MySQL and MariaDB both have their Audit Login Plugins.

Conclusion

While LOAD DATA INFILE and LOAD DATA LOCAL INFILE are valuable tools for efficiently importing data into database tables, they have inherent security risks that DBAs must manage. By understanding the differences between these commands and implementing robust security practices, DBAs can safeguard their database environments against potential threats. Always weigh the convenience of these commands against the security implications, and when in doubt, err on the side of caution.

Implementing a zero-trust approach, where every action is verified and monitored, is essential in maintaining a secure and reliable database infrastructure.