All Select Null,null,null,null,null,null,null,null-- Mxyc - {keyword}') Union

: This is the heart of the attack. It tells the database to combine the results of the original (legitimate) search with a new set of data the attacker wants to see.

If a website is vulnerable to this, an attacker doesn't just stop at NULL . They eventually replace those NULL s with commands to extract sensitive info—like your —and display them right on the screen where the "Keyword" results should have been. How Developers Stop This

: This attempts to "break out" of the developer’s intended code by closing a data field and a function. : This is the heart of the attack

Here is a look into what that string is designed to do and why it’s a fundamental concept in web security. What is this string?

Modern web development has largely moved past this threat using a technique called (or Parameterized Queries). Instead of letting user input mix directly with the code, the database is told: "Treat this input strictly as text, no matter what symbols are inside it." They eventually replace those NULL s with commands

: This is the SQL comment symbol. It tells the database to ignore everything else in the original code, effectively "turning off" the security checks or logic that were supposed to happen next. The Goal: Data Exfiltration

The text ') UNION ALL SELECT NULL,NULL...-- is a malicious payload used to test for vulnerabilities in a database. What is this string

It looks like you've included a in your request. In the world of cybersecurity, that specific snippet is a classic example of an "Union-based" attack.