: 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.
The string you provided is a designed to discover the number of columns in a database table. Breakdown of the Payload
: 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. {KEYWORD}) UNION ALL SELECT NULL,NULL,NULL,NULL,NULL-- ZkhD
An attacker (or security researcher) would send this payload to an application to see if it returns an error or a successful response.
: The number of NULL values (5 in this case) does not match the number of columns in the original table. : The original table has exactly 5 columns
: 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.
: 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. Breakdown of the Payload : This is likely
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