Command and code injection
Someone tries to run their own commands on your server.
What it is
Shell commands or program code sent as input, hoping the server runs it.
- ; cat /etc/passwd after a file name
- PHP code in an upload's name
- A crafted object that runs code when the site reads it
Why it matters
When it works, the attacker controls the server and everything on it.
If a real visitor is ever stopped
This can catch real text about programming, or a tool of yours that sends commands on purpose. Mark the request as real and that one field is let through.