: When the number of NULL s matches exactly (in your case, 8 columns), the page will load normally or show an extra blank row, confirming the database structure. Why This Matters
: If the number of NULL values does not match the original query's column count, the server usually returns an error (like a 500 Internal Server Error).
The string you provided is a classic payload. It is not a feature of a specific software product but rather a technique used by security researchers and attackers to probe databases for vulnerabilities. Purpose of the Payload : When the number of NULL s matches
Once an attacker knows there are 8 columns, they can replace the NULL values with commands to extract sensitive data, such as usernames, passwords, or database versions. SQL injection UNION attacks | Web Security Academy
The primary goal of this specific syntax is to returned by the original, legitimate database query. It is not a feature of a specific
: This is a SQL comment marker that tells the database to ignore the rest of the original query, preventing errors from leftover code. How it Works
: Attackers use NULL because it is compatible with almost every data type (integers, strings, dates), making it the "safest" way to avoid syntax errors while testing column counts. : This is a SQL comment marker that
: This command attempts to append a new set of results to the original query's output.