{keyword}) Union All Select Null,null,null,null,null-- Zkhd Official

: The attacker uses a specific number of NULL values to match the number of columns in the original query's SELECT statement. NULL is used because it is compatible with almost any data type (strings, integers, dates), maximizing the chance that the injected query will succeed.

: The original table has exactly 5 columns. This confirms a vulnerability and allows the attacker to move to the next step: identifying which columns can display sensitive data. {KEYWORD}) UNION ALL SELECT NULL,NULL,NULL,NULL,NULL-- ZkhD

: This command combines the result set of the original query with a new set of data. UNION ALL is used instead of UNION because it is often faster and does not remove duplicates, which can be useful for certain types of data extraction. : The attacker uses a specific number of

The string you provided is a designed to discover the number of columns in a database table. Breakdown of the Payload This confirms a vulnerability and allows the attacker

An attacker (or security researcher) would send this payload to an application to see if it returns an error or a successful response.