How do you identify and prevent SQL injection attacks, detailing the vulnerabilities involved?

SQL injection attacks are identified and prevented by addressing the vulnerabilities that allow them to occur. The primary vulnerability is insufficient input validation and sanitization of user-supplied data used in SQL queries. This allows attackers to inject malicious SQL code into the query, which can then be executed by the database server. Identification involves several methods. Code reviews can identify areas where user input is directly incorporated into SQL queries without proper sanitization. Web application firewalls (WAFs) can be configured to detect and block SQL injection attempts by analyzing HTTP requests for suspicious patterns. Penetration testing involves simulating attacks to identify vulnerabilities in the application. Log analysis of web server and database logs can reveal SQL injection attempts by identifying unusual or malformed SQL queries. Prevention methods include: Prepared statements (Parameterized queries), which separate the SQL code from the user-supplied data, preventing the data from being interpreted as code. Input validation, which involves verifying that user input conforms to the expected format and range, and rejecting any input that does not. Output encoding, which involves encoding data before it is displayed to the user, preventing cross-site scripting (XSS) attacks, which can be used to inject SQL code. Least privilege principle, which involves granting database users only the minimum necessary privileges, limiting the damage that can be caused by a successful SQL injection attack. Regular security updates, which ensure that the database server and web application are protected against known vulnerabilities. For example, instead of directly embedding a username from user input into a SQL query like `SELECT FROM users WHERE username = '" + username + "'`, use a prepared statement: `SELECT FROM users WHERE username = ?`, then bind the `username` variable to the `?` placeholder.