Page 611 - (ISC)² CISSP Certified Information Systems Security Professional Official Study Guide

control software interfaces.

In theory, the static design of SCADA, PLC, and DCS units and their
minimal human interfaces should make the system fairly resistant to

compromise or modification. Thus, little security was built into these
industrial control devices, especially in the past. But there have been
several well-known compromises of industrial control systems in
recent years; for example, Stuxnet delivered the first-ever rootkit to a
SCADA system located in a nuclear facility. Many SCADA vendors

have started implementing security improvements into their solutions
in order to prevent or at least reduce future compromises. However, in
practice, SCADA and ICS systems are still often poorly secured,
vulnerable, and infrequently updated, and older versions not designed
for security are still in widespread use.