Today’s supervisory control and data acquisition (SCADA) systems have been designed with little or no attention to security. For example, data in SCADA systems are often sent “in the clear.” Protocols for accepting commands are open, with no authentication required. Control channels are often wireless or leased lines that pass through commercial telecommunications facilities. For example, unencrypted radio-frequency command pathways to SCADA systems are common and, for economic reasons, the Internet itself is increasingly used as a primary command pathway. Thus, there is minimal protection against the forgery of control messages or of data and status messages. Such control paths present obvious vulnerabilities.
In addition, today’s SCADA systems are built from commercial off-the-shelf components and are based on operating systems that are known to be insecure. Deregulation has meant placing a premium on the efficient use of existing capacity, and hence interconnections to shift supply from one location to another have increased. Problems of such distributed dynamic control, in combination with the complex, highly interactive nature of the system being controlled, have become major issues in operating the power grid reliably.
A final problem arises because of the real-time nature of SCADA systems, in which timing may be critical to performance and optimal efficiency (timing is important because interrupts and other operations can demand millisecond accuracy): Security add-ons in such an environment can complicate timing estimates and can cause severe degradation to SCADA performance.
Compounding the difficulty of SCADA systems’ tasks is the fact that information about their vulnerability is so readily available. Such information was first brought into general view in 1998-1999, when numerous details on potential Y2K problems were put up on the World Wide Web. Additional information of greater detail—dealing with potential attacks that were directly or indirectly connected to the President’s Commission on Critical Infrastructure Protection—was subsequently posted on Web pages as well. Product data and educational videotapes from engineering associations can be used to familiarize potential attackers with the basics of the grid and with specific elements. Information obtained through semiautomated reconnaissance to probe and scan the networks of a variety of power suppliers could provide terrorists with detailed information about the internals of the SCADA network, down to the level of specific makes and models of equipment used and version releases of corresponding software. And more inside information could be obtained from sympathetic engineers and operators.
Some disaster scenarios result in significant loss or damage that is all out of proportion to the actual functionality or capability destroyed. In particular, localized damage that results in massive loss of confidence in some critical part of the infrastructure could have such a disproportionate impact. For example, if terror-