: This is a SQL comment, which tells the database to ignore the rest of the original, legitimate query that follows. The Goal of the Attack
: Appends a new set of results to the original query's output. : This is a SQL comment, which tells
If the original query has 8 columns, the page will likely load normally or show an extra row of empty data. : Attempts to select 8 columns of "null" data
: Attempts to select 8 columns of "null" data. The payload you provided, ' UNION ALL SELECT
This specific string is designed to be appended to a vulnerable input field (the {KEYWORD} in your example) to probe the database structure: : Closes the original string literal in the SQL query.
NULL is used because it is compatible with almost any data type (string, integer, date, etc.), ensuring the query won't fail due to data type mismatches.
The payload you provided, ' UNION ALL SELECT NULL,NULL,NULL,NULL,NULL,NULL,NULL,NULL-- , is a common pattern used in to determine the number of columns returned by an original database query. What this Payload Does