This represents the original search term or input value that a legitimate user would enter. In an attack scenario, the "payload" (the rest of the string) is appended to this keyword to trick the database into executing an additional command alongside the intended query. 2. UNION ALL
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. This represents the original search term or input
: NULL is used because it is compatible with almost any data type (integers, strings, dates, etc.). UNION ALL If the page returns an error
This string is a classic example of a used by security researchers and attackers to probe a website's database for vulnerabilities. : NULL is used because it is compatible
: The database returns a row of empty data. The attacker now knows the table has 6 columns and can proceed to more dangerous injections, such as UNION SELECT username, password, NULL... to steal sensitive information.
: A website takes user input and places it directly into a SQL query without "cleaning" it first.