More than likely the SCADA systems themselves were fine, but the PCs for managing those systems were AD joined and people couldn't login to actually run the management software.
Its very common in custom hardware setups to have a standing system that interfaces with the physical hardware and PLC and then the user friendly software for instructing that controller on what you want to be on a PC talking to it over serial or the network. Obviously if the computer is inaccessible you can't adjust settings, but the system continues to run fine.
Its very common in custom hardware setups to have a standing system that interfaces with the physical hardware and PLC and then the user friendly software for instructing that controller on what you want to be on a PC talking to it over serial or the network. Obviously if the computer is inaccessible you can't adjust settings, but the system continues to run fine.