: This command tells the database to combine the results of the original (legitimate) search with a second search created by the attacker.
This specific line of code is designed to trick a database into revealing information it shouldn't. Here is what each part does:
: The attacker uses NULL to match the number of columns in the original query without causing a data type error. The string in the middle is a "fingerprint"—if the word "ZZTyernefl" appears on the website, the attacker knows the injection worked and exactly which column displays data on the screen. : This command tells the database to combine
To understand how this works in "real life," imagine you are at a library:
The string you provided is a classic example of a used for a "UNION-based" attack. The "Anatomy" of the Payload The string in the middle is a "fingerprint"—if
Never trust data coming from a user. Always filter it to remove characters like ' , -- , and ; . SQL injection UNION attacks | Web Security Academy
: This is a comment marker in SQL. It tells the database to ignore everything that comes after it, effectively "breaking" the rest of the original, legitimate code so it doesn't cause an error. A Helpful Story: The Librarian and the Hidden Note Always filter it to remove characters like ' , -- , and ;