The string -3216' UNION ALL SELECT 34,34,34,34# is a classic example of a used to exploit vulnerabilities in database-driven applications. Breaking Down the Payload
: This part creates a "fake" row of data. Attackers use this to determine the exact number of columns required for the UNION to work, as both queries must have the same number of columns. -3216' UNION ALL SELECT 34,34,34,34#
: In MySQL, this symbol marks the rest of the original query as a comment , effectively deleting the remaining code (like WHERE clauses or authentication checks) to bypass security. Purpose of This "Piece" The string -3216' UNION ALL SELECT 34,34,34,34# is
: This operator combines the results of the original query with a new one. By using UNION ALL , the attacker can inject their own data into the results page. : In MySQL, this symbol marks the rest
: If the page displays the number "34" several times, it confirms the site is vulnerable to SQL injection.
: Determining the column count is the first step toward extracting sensitive data, such as usernames and passwords.
: This is an intentional "invalid" input (like a negative ID) designed to break the original SQL query's logic and ensure the database returns no results for the first part of the operation.