Sql injection

1. The document discusses various SQL injection vulnerabilities and techniques for exploiting them, including on Metasploitable, DVWA, and Sqli-labs platforms. 2. It provides examples of payloads to extract database, table, and user information from Sqli-labs lessons 29, 32, 33, and 36. 3. The document also discusses challenges of SQL injection on MySQL databases using GBK encoding, and mitigations like addslashes(), preg_replace(), and mysql_real_escape_string().