{keyword}) Union All Select Null,null,null,null,null,null# -

: This treats user input as data, not as executable code.

: This is the core of the attack. The UNION operator combines the results of two or more SELECT statements into a single result set. ALL ensures that duplicate rows are kept. {KEYWORD}) UNION ALL SELECT NULL,NULL,NULL,NULL,NULL,NULL#

To protect your application from this type of attack, you should avoid building queries using simple string concatenation. Instead, use: : This treats user input as data, not as executable code

: This is a common reconnaissance technique. An attacker uses NULL values to determine the exact number of columns returned by the original query. If the number of NULL s doesn't match the original column count, the database will usually throw an error. By adding or removing NULL s, an attacker can find the correct structure. ALL ensures that duplicate rows are kept

: Only allow expected characters and formats.

: This part attempts to "break out" of the existing SQL command. The closing parenthesis ) is used to close a function or a nested query that the developer originally intended.

: Most modern frameworks like Hibernate or Entity Framework handle this protection automatically.