Stuxnet specifically targets PLCs controlling industrial centrifuges using a vulnerability in Windows USB device handling (which has been corrected for some time). It then propagated across the network, exploiting a vulnerability in a Siemens Step 7 control software. The Siemens software had a well-known ‘back door’ which allowed high privilege access to their control software.
Stuxnet, as such, cannot compromise the Survalent SCADA system, because most of the required conditions do not apply.
The Stuxnet worm reportedly makes itself inert if no Siemens software is found on the network.
The stolen software certificates that allowed installation of the malware have subsequently been revoked by Verisign, the issuer.
Stuxnet was designed to target and debilitate industrial centrifuges.
Factors that will reduce risk from engineered attacks similar to Stuxnet
Proper maintenance of operating system patches
User training in the safe use of USB drives (‘thumb drives’)
Properly configured firewalls