(or sometimes -- ): A comment marker that hides the rest of the original SQL query, preventing syntax errors.
: A random string identifier often used in automated attacks to verify if the injected query is successfully displayed in the application response. Purpose and Workflow SQL injection UNION attacks | Web Security Academy (or sometimes -- ): A comment marker that
: Fills columns with NULL values to match the column count of the original query, which is required for UNION to work. The attacker keeps adding NULL s until the error disappears (often 500 internal server error) and a '200 OK' response is received. The attacker keeps adding NULL s until the
This SQL injection payload ( ' UNION ALL SELECT NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL-- vITQ ) is a classic technique used in to determine the exact number of columns returned by a vulnerable web application's original database query. Payload Breakdown ' : Closes the original SQL statement's string parameter. (or sometimes -- ): A comment marker that