Physical measures
One of the easiest and safest security measures is physical protection. Make sure that only administrators and technicians have access to the device. Attacks via physical access such as USB flash drives and other data carriers, which represent one of the biggest risks, can be reduced in this way. Physical protection of a device is achieved, for example, by means of a lockable control cabinet.
Locked control cabinet
The standard environment for an industrial controller should be a locked control cabinet. The attack surface is greatly reduced by allowing only individual interfaces to leave the control cabinet. The interfaces led out there should be additionally protected (lockable). Access to the control cabinet should only be given to persons who need it in order to perform their tasks. Electronic locking systems can also be used, for example based on smart cards. As with all key management systems, access to the control cabinet should be revoked when it is no longer required.
Video surveillance
Video surveillance is suitable for shift working in environments where many people need access to a controller or where facilities are geographically dispersed. However, video surveillance can only detect attacks and not prevent them. This measure is therefore only useful in combination with other measures.