{keyword}) Union All Select Null,null,null,null,null-- Zkhd May 2026

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

The string you provided is a designed to discover the number of columns in a database table. Breakdown of the Payload {KEYWORD}) UNION ALL SELECT NULL,NULL,NULL,NULL,NULL-- ZkhD

: 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. An attacker (or security researcher) would send this

: This part attempts to break out of the existing SQL query structure. The closing parenthesis ) is used to "close" a likely function or subquery in the application's original code. {KEYWORD}) UNION ALL SELECT NULL,NULL,NULL,NULL,NULL-- ZkhD