What is injection?

Injection is a type of security flaw where an attacker tricks a program into running malicious code or commands that were never intended by the original developer. The most common example is SQL injection, where harmful SQL statements are inserted into a database query.

Let's break it down

  • A program asks for input (like a username or search term).
  • The program builds a command or query using that input.
  • If the input isn’t properly checked, an attacker can add extra code (the “injection”) that changes the original command.
  • The altered command runs on the server, giving the attacker access to data or control.

Why does it matter?

When injection succeeds, attackers can read, modify, or delete sensitive data, bypass authentication, or even take over the entire system. This can lead to data breaches, financial loss, and damage to a company’s reputation.

Where is it used?

Injection attacks target any system that builds commands or queries from user input, such as:

  • Web applications that talk to databases (SQL injection)
  • Command‑line tools that execute shell commands (command injection)
  • APIs that construct NoSQL queries (NoSQL injection)
  • Templates that render HTML (template injection)

Good things about it

Understanding injection helps developers:

  • Write safer code by validating and sanitizing input.
  • Use prepared statements and parameterized queries, which automatically protect against many injections.
  • Build more robust applications that resist a wide range of attacks.

Not-so-good things

  • Injection flaws are easy to find and exploit, especially in legacy code.
  • Fixing them often requires refactoring existing code, which can be time‑consuming.
  • If not addressed, they can expose massive amounts of data and give attackers a foothold for further attacks.