MySQL Overview#

1. What is MySQL:
   • MySQL is an open-source SQL relational database management system (RDBMS) developed by Oracle.
   • It stores data in tables with rows and columns, optimized for quick retrieval and minimal storage.
   • MySQL operates on the client-server principle: a server manages the data, while clients send queries to interact with the database.
2. MySQL Clients:
   • Clients use SQL queries to interact with the MySQL server, allowing for data manipulation such as insertions, deletions, and modifications.
   • Web applications commonly utilize MySQL to store content, such as user data and system configurations, for dynamic websites.
   • WordPress, for example, uses MySQL to store posts, user data, and other content.
3. MySQL Databases:
   • MySQL is commonly used in a LAMP (Linux, Apache, MySQL, PHP) stack, providing a backend database for web applications.
   • It stores diverse data like headers, links, user credentials, and even sensitive information, though it’s often encrypted for security.
4. MySQL Commands:
   • SQL commands allow the manipulation and retrieval of data, and can be used for operations such as adding, modifying, or deleting data.
   • Other commands enable structural changes like creating or deleting tables and relationships.
   • Common commands include show databases;, use <database>;, show tables;, and data manipulation commands like select, insert, update, delete.
5. MariaDB:
   • MariaDB is a fork of MySQL, created by MySQL’s original developers after Oracle acquired MySQL. It’s designed to be fully compatible with MySQL while offering additional features and improvements.

Default Configuration#

1. Configuration Example:
   • You provided a configuration file snippet showing settings for a MySQL instance (mysqld.cnf), such as user, pid-file, and datadir, indicating how MySQL is configured by default.
2. Dangerous Settings:
   • Some configuration settings can pose security risks, such as storing plain-text passwords or enabling overly verbose error messages.
   • For example, sql_warnings and debug settings can expose sensitive information that attackers might use.

Footprinting MySQL Server#

1. Scanning for Open MySQL Ports:
   • Using nmap, you can scan for open MySQL ports (usually 3306) to gather information about the MySQL server, including version, users, and potential vulnerabilities.
   • The example shows how a scan can reveal vulnerable user accounts (e.g., root, admin, etc.) with empty passwords, highlighting security risks.
2. Interacting with MySQL:
   • Once you have valid credentials (discovered via brute-force or other methods), you can interact with the MySQL server, using commands to view databases (show databases;), switch databases (use <db>;), and list tables (show tables;).
   • You also showed examples of how to retrieve metadata about the server’s configuration, such as the MySQL version and user details.

MySQL Security Considerations:#

1. User and Password Management:
   • Configurations like user and password need to be securely managed. Exposing these in plaintext can lead to critical security breaches.
   • Ensure proper access controls on configuration files to avoid unauthorized access to sensitive information.
2. Verbose Error Output:
   • Configuring MySQL to display detailed error messages, such as via the debug or sql_warnings settings, can give attackers valuable information about the database structure and potential vulnerabilities.
   • It’s crucial to disable or limit error output in production environments.

MySQL Commands Recap#

1. Common Commands:
   • mysql -u <user> -p<password> -h <IP address>: Connect to the MySQL server.
   • show databases;: List all databases.
   • use <database>;: Select a specific database to work with.
   • show tables;: Display tables within the selected database.

These key points give a solid foundation for working with MySQL and understanding its potential security risks, particularly in web applications. If you’re working with MySQL in your own projects, it’s important to take the necessary steps to secure your databases, such as using encrypted passwords, limiting access to the database, and securing your configuration files.