: This represents the original input (like a product category or search term) that the application expects.
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 : This represents the original input (like a
: 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 How it Works : When the number of
: 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 Purpose of the Payload : An attacker starts
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
: An attacker starts with one NULL and keeps adding more (e.g., NULL, NULL , then NULL, NULL, NULL ).
: This command attempts to append a new set of results to the original query's output.