Environmental Engineering Reference
In-Depth Information
1.
Identify all connections to SCADA networks.
Conduct a thorough risk
analysis to assess the risk and necessity of each connection to the
SCADA network. Develop a comprehensive understanding of all
connections to the SCADA network and how well those connec-
tions are protected. Identify and evaluate the following types of
connections:
• Internal local area and wide area networks, including business
networks
• The Internet
• Wireless network devices, including satellite uplinks
• Modem or dial-up connections
• Connections to business partners, vendors or regulatory agencies
2.
Disconnect unnecessary connections to the SCADA network.
To ensure
the highest degree of security of SCADA systems, isolate the SCADA
network from other network connections to as great a degree as
possible. Any connection to another network introduces security
risks, particularly if the connection creates a pathway from or to
the Internet. Although direct connections with other networks may
allow important information to be passed efficiently and conve-
niently, insecure connections are simply not worth the risk; isolation
of the SCADA network must be a primary goal to provide needed
protection. Strategies such as the utilization of demilitarized zones
(DMZs) and data warehousing can facilitate the secure transfer of
data from the SCADA network to business networks; however, they
must be designed and implemented properly to avoid the introduc-
tion of additional risk through improper configuration.
3.
Evaluate and strengthen the security of any remaining connections to
the SCADA networks.
Conduct penetration testing or vulnerability
analysis of any remaining connections to the SCADA network to
evaluate the protection posture associated with these pathways.
Use this information in conjunction with risk-management pro-
cesses to develop a robust protection strategy for any pathways to
the SCADA network. Because the SCADA network is only as secure
as its weakest connecting point, it is essential to implement fire-
walls, intrusion detection systems (IDSs), and other appropriate
security measures at each point of entry. Configure firewall rules to
prohibit access from and to the SCADA network, and be as specific
as possible when permitting approved connections. For example,
an Independent System Operator (ISO) should not be granted blan-
ket network access simply because of a need for a connection to
certain components of the SCADA system. Strategically place IDSs
at each entry point to alert security personnel of potential breaches
