Six Doors Into the Intersection
Attackers look for the device someone forgot to own.
An attacker doesn't need your best-protected controller. They only need the one nobody checked. Once they're on the signal network at one point, they may be able to reach every intersection on it. The Michigan researchers said it plainly: an attacker only has to beat the weakest link.
In a traffic system, there are six usual ways in.
| Door | What it looks like | How you shut it |
|---|---|---|
| 1. The factory password | A controller, radio or switch still uses the login it shipped with, or one login shared across the whole corridor | Give each device its own login, then check it still does its job |
| 2. The open control screen | A controller's web page or management port can be reached from the internet or from a network that has no business seeing it | Close the outside access and allow only approved paths |
| 3. The flat cabinet | The controller, camera, radio and every other device share one switch with no rules between them | Let each device talk only to what it needs |
| Door | What it looks like | How you shut it |
|---|---|---|
| 4. The login that never left | A contractor, vendor or former employee still has working access | See every login and session, approve what's needed, remove what isn't |
| 5. The radio nobody watches | Radio links between intersections, or cellular modems in the cabinet, carry traffic nobody inspects | Treat the airwaves around the corridor as part of the network |
| 6. The fix nobody checked | A security change cuts off the attacker and also cuts the controller off from the traffic center, or trips it into flash | Require a security check and a service check before calling it done |
The first five doors are about how attackers get in. The sixth is about how defenders hurt themselves on the way out. It's the one most agencies never measure.
Ask your team: Which of these six doors would you be least comfortable swearing is shut on every corridor?