Sasser Worm Infection in Process Control System.

A worm (Sasser) infected a number of HMIs on a process control network. Initial point of infection suspected as from an external network connected to the same firewall as the PCN. None of the HMIs were installed with AV software, and none had been patched. All were running on a Windows based OS. The firewall, although running an IDS service, did not have a fully secured rulebase, which allowed the infection to pass onto the PCN.

None, as not all HMIs became infected.