: The attacker wants the database to return the results of the original query plus the results of their injected query.
This string is a classic example of a used by security researchers and attackers to probe a website's database for vulnerabilities. : The attacker wants the database to return
If the page returns an error (like "The used SELECT statements have a different number of columns"), the attacker will try again with five or seven NULL values until the error disappears. 4. -- (The Comment) In SQL, double-dashes signify the start of a comment. If the page loads normally, the attacker knows
: This "comments out" the rest of the original SQL query written by the developers. If the page loads normally
If the page loads normally, the attacker knows the database is expecting 6 columns.
This is likely a or "signature" used by an automated vulnerability scanner (such as Burp Suite, SQLmap, or Acunetix).