: The attacker is trying to determine how many columns the original database table has. By providing five NULL values, they are testing if the original query also returns five columns (the number of columns must match for a UNION to work).
If you found this in a product review section, a log file, or a search bar, it means someone (or an automated bot) was . They were checking if the site properly "sanitizes" user input or if it is vulnerable to data theft. {KEYWORD}') UNION ALL SELECT NULL,NULL,NULL,NULL,NULL-- DyYf
: This part attempts to "break out" of a predefined search query. The ') is used to close a string literal and a parenthesis in the backend code, allowing the attacker to append their own commands. : The attacker is trying to determine how