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

: 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.

: 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. {KEYWORD}) UNION ALL SELECT NULL,NULL,NULL,NULL,NULL-- ZkhD

: 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 is likely a random string or a "signature" used by a vulnerability scanner (like Burp Suite or sqlmap) to track if the payload was successfully reflected in the application's response. UNION ALL is used instead of UNION because

For more in-depth technical guides, you can visit the Web Security Academy or community forums like Medium .

: This is a comment indicator that tells the database to ignore the rest of the original query that follows.

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