Adversaries may attempt to manipulate the information reported back to operators or controllers. This manipulation may be short term or sustained. During this time the process itself could be in a much different state than what is reported.   
Operators may be fooled into doing something that is harmful to the system in a loss of view situation. With a manipulated view into the systems, operators may issue inappropriate control sequences that introduce faults or catastrophic failures into the system. Business analysis systems can also be provided with inaccurate data leading to bad management decisions.
Industroyer's OPC module can brute force values and will send out a 0x01 status which for the target systems equates to a Primary Variable Out of Limits misdirecting operators from understanding protective relay status. 
Protocols used for control functions should provide authenticity through MAC functions or digital signatures. If not, utilize bump-in-the-wire devices or VPNs to enforce communication authenticity between devices that are not capable of supporting this (e.g., legacy controllers, RTUs).
Take and store data backups from end user systems and critical servers. Ensure backup and storage systems are hardened and kept separate from the corporate network to prevent compromise. Maintain and exercise incident response plans , including the management of gold-copy back-up images and configurations for key systems to enable quick recovery and response from adversarial activities that impact control, view, or availability.
|M0810||Out-of-Band Communications Channel||
Utilize out-of-band communication to validate the integrity of data from the primary channel.