## Patch Management

The most effective security control.

### The Patch Tuesday Cycle
Microsoft releases patches on the 2nd Tuesday of every month.
1.  **Tuesday**: Patches released.
2.  **Wednesday**: Testing in "Dev" environment. (Does the patch break the App?).
3.  **Thursday**: Deploy to "Pilot" group (10% of users).
4.  **Friday**: Deploy to everyone.

### Legacy Systems
What if you CAN'T patch? (e.g., MRI machine running Windows XP).
**Mitigating Controls**:
*   **Air Gap**: Disconnect from internet.
*   **VLAN**: Segregate it so it can only talk to the Printer.
*   **IPS**: Virtual Patching (Block the exploit at the network level).