Never trust user input. Use allow-lists to ensure only expected data types (like numbers or plain text) are processed.
The text you provided is a classic example of a payload. Specifically, it uses the UNION ALL SELECT statement to attempt to trick a database into revealing unauthorized information or appending malicious data to a legitimate query. What is happening in this string? Never trust user input
: This is a string concatenation. The attacker is trying to print a unique string (like a "fingerprint") to the screen. If "qbqvqoQMUFBfpihqqbqq" appears on the webpage, the attacker knows the site is vulnerable. Specifically, it uses the UNION ALL SELECT statement
This is the #1 defense. It ensures the database treats input as literal text, not executable code. The attacker is trying to print a unique
: This is a comment operator in SQL. It tells the database to ignore the rest of the legitimate code that follows, effectively neutralizing any security checks at the end of the original query. Why you might be seeing this
: These are "dummy" values used to match the number of columns in the original database table. If the column counts don't match, the attack fails, so hackers often guess the number of columns this way.