ADAPTING SCADA SYSTEMS TO CLOUD COMPUTING

ENVIRONMENT

Zhixiong Chen and Donovan Evan

Math and CIS, Mercy College, Dobbs Ferry, New York, NY 10522, U.S.A.

Keywords: Cloud computing, Supervisory control.

Abstract. Supervisory Control and Data Acquisition (SCADA) systems have existed for over 50 years. Yet, they are

still widely used in national critical infrastructures like New York Metro transportation system, NY water-

way control systems and power grid. This paper examines the evolution of SCADA systems from closed

SCADA systems to open networked SCADA systems and discusses issues adapting SCADA systems into

cloud computing paradigm. We propose a framework that secures SCADA systems under cloud environ-

ment. It provides reasonable assurance of such adaptation and migration. Finally, we apply it to NY Metro

North Subway and Rail Transportation system.

1 INTRODUCTION

Supervisory Control and Data Acquisition or

SCADA refers to any systems and networks that

monitor, manage, and control automation, produc-

tion and distribution (SCADA and CS).

SCADA systems are widely used in nations’ crit-

ical infrastructure such as transportation, telecom-

munications, energy, waste and water treatment, and

manufacturing (SCADA).

Securing SCADA systems is a national priority

because disruption of them can have significant

consequences for public health and safety (PDD 63).

When SCADA systems are set to be isolated

standalone control systems, security concerns are

more on the physical access control and operators.

When SCADA systems are networked and/or

hooked into internet, the security concerns are

shifted to more or less the same as we do to network

security and information systems. A whole range of

security issues such as access control, business con-

tinuity and disaster recovery planning, security go-

vernance and risk management, law regulations and

compliance, operations security; environmental

security, security architecture and design, and tele-

communications and network security need to be

addressed (Krutz, 2006; Chen and Yoon, 2010 ).

For the last several years, cloud computing is

moving from industry to academia (instead of the

other direction like many classical cases) and is

making leap in IT evolution. It is a model for enabl-

ing convenient, on-demand network access to a

shared pool of configurable computing resources

(e.g., networks, servers, storage, applications, and

services) that can be rapidly provisioned and re-

leased with minimal management effort or service

provider interaction (NIST). With on-demand self-

service, broad network access, resource pooling,

rapid elasticity and measured services, cloud compu-

ting increases greatly productivity and efficiency

(NIST). At the same time, security is a great concern

(Cloud Security Alliance, 2009). Many research

papers and frameworks are devoted to this area (for

example, see (Krutz, 2006; NIST; Cloud Security

Alliance, 2009; Chen and Yoon, 2010; http://

en.wikipedia.org/; Forrest, 2009; NIST, 2010;

OSAG). Cloud Security Alliance identifies thirteen

(13) domains that need to be covered in securing

cloud computing environment (Krutz, 2006) while

Chen et al discusses compliances for services dep-

loyment models thoroughly (Chen and Yoon, 2010).

Migrating networked SCADA systems to a cloud

environment, either a private cloud or a public

cloud, is sure a path for better data sharing, data

managing and quick decision making. But, security

and compliance, especially for public cloud are

certainly big concerns. As we see recently that a

window computer worm, stuxnet and its variants are

found to target industrial systems and their payload

to PLC in SCADA systems (http://

en.wikipedia.org/). It is a very sophisticated attack to

SCADA systems. We can only expect that a big

559

Chen Z. and Evan D..

ADAPTING SCADA SYSTEMS TO CLOUD COMPUTING ENVIRONMENT.

DOI: 10.5220/0003614705590563

In Proceedings of the 13th International Conference on Enterprise Information Systems (IAST-2011), pages 559-563

ISBN: 978-989-8425-55-3

 2011 SCITEPRESS (Science and Technology Publications, Lda.)

organization or even government agency can have

such capabilities.

In this paper, we will address these issues from

classical SCADA systems to cloud environment. In

section 2, we examine the evolution of SCADA

systems while in section 3, after summarizing cloud

computing services deployment models, we discuss

the feasibility of moving networked SCADA sys-

tems to cloud environment, from private cloud,

community cloud to public cloud. In section 4, we

list specific security and compliance issues facing

migrating SCADA systems into cloud and propose a

framework of securing SCADA systems. We use

NY Metro North Subway and Rail systems as an

example to demonstrate our work. The final section

is devoted to discussion and further research and

field work.

2 EVOLUTION OF SCADA

SYSTEMS

Traditionally, Electrical Engineers consider SCADA

systems as control systems (CS). A typical SCADA

system architecture can be demonstrated by Figure 1

in which a SCADA host uses Human Machine Inter-

face (HMI) to connect to several Remote Terminal

Units (RTUs) or Programmable Logic Controllers

(PLCs) and to acquire data and to make controls.

RTUs and PLCs are in closed loop control to field

elements such as sensors, valves, pumps, switched

and motors via EIA232 and EIA485.

Human operators control supervisory functions

and monitor them. The monitoring devices conti-

nually update data, which enable operators to man-

age daily operations locally and remotely as well.

HMI systems have evolved from light indication

panels and analog gauges to computerize graphical

display with real time indication and response fea-

tures.

Communication medium is more on copper line

due to the unreliability of earlier radio systems and

the high cost of ISDN lines. Communication proto-

cols are mostly in the application layer and most of

them are still proprietary like MODBUS from Mod-

icon. The trend is that these proprietary protocols are

moving toward open and standardized protocols, for

example, Profibus from Siemens, Device Net from

Allen Bradley, DNP3 and subsequently IEC61850

from EPRI, and IEEE 60870.

Computer scientists consider SCADA systems as

connected IT systems. A typical networked SCADA

system can be depicted by Figure 2 in which several

SCADA hosts uses HMI to connect Master Terminal

Units (MTU) that serves as a basic central control

station (BCCS). The BCCS hooks with controllers

like RTUs and PLCs securely via wireless network,

Switched Public Telephone Network or Internet.

These controllers link to field elements.

The efforts of moving standalone SCADA sys-

tems to networked SCADA systems represent an

evolution path of SCADA systems when they were

first appeared about fifty years ago.

Figure 1: A typical Standalone SCADA System.

Figure 2: A typical

Networked SCADA System.

3 ADAPTING SCADA SYSTEMS

TO CLOUD COMPUTING

The notion of moving SCADA systems into cloud

computing is quite controversial and eye catching.

Some researchers believe it will benefit greatly for

the next generation SCADA systems such as smart

grid, renewable energy (Vyatkin, 2010; Gustavsson

and Ståhl, 2010; Geberslassie and Bitzerl, 2010) and

the virtualization concept in cloud is actually en-

hancing security (Communication in ACM) while

others believe the virtualization is overkill, especial-

ly when defending malware such as rootkit (Bratus,

2010).

In our survey of NY Metro North Subway and

Rail SCADA system (Figure 3 and 4), while it is

wary about the idea of opening its SCADA system

to a cloud, especially about to a public cloud, it

believes it will benefit if it adopts some of the typi-

ICEIS 2011 - 13th International Conference on Enterprise Information Systems

560

cal cloud features or characteristics like self-

configuration, broad network access and resource

pooling.

Figure 3: Control Room.

Figure 4: Communication Room.

For example, virtualization can help mass confi-

guration if it updates its out-dated controllers to

more standard network enabled ones with more

processing power and memory. Another example is

using IP cameras to monitor remote controllers and

field elements can be done in a private cloud envi-

ronment. The surveillance system can be indepen-

dent from the existing SCADA system or be a part

of SCADA system that can trigger a sequence of

control actions when undesired events like intruders,

fire alarm, and power shortage are detected.

Processing, protecting and preserving these high

volume video streaming data is an ideal candidate

for cloud computing.

Because of security concerns in most times is tri-

umph over cost saving due to the nature of SCADA

systems, we do not see the possibility of moving

SCADA to a public cloud in the near future unless

some special arrangements or dramatic security

technology advancement. Like many big trading

companies that do not use a public cloud but shift to

a private cloud internally, SCADA systems can

adapt to a private cloud or even a community cloud

that shares the same concerns. As we know, cloud

computing is basically a collection of net centric

technologies. A private cloud can shield the notion

of open SCADA systems to public although it is not

absolutely true. At the same time, SCADA systems

in the cloud can share the computing resources

needed, sharing data acquired from field controllers

so that decision makers can have accurate and near

real time data.

We need to emphasize that a private cloud is not

sharing controls while sharing data. Technically,

sharing data can be done using various mechanisms.

One non-intrusive mechanism is to capture image

displayed in an operator screen inside a SCADA

host. This will make the alteration of data during

transmission much harder. It addresses more data

integrity than confidentiality. So the adaptation

should move in a careful staging process.

Another area is to provide redundancy resources.

SCADA systems controllers can stretch over a large

geography area. They are vulnerable to terrorism,

vandalism or lost of system controls. System relia-

bility is of the utmost importance; therefore redun-

dancy is prevalent throughout the system. The Con-

trol center and each RTU have a dedicated UPS

system, redundant communication lines, and servers.

Cloud network would solve many of these issues.

4 SECURITY AND COMPLIANCE

OF SCADA SYSTEMS IN

CLOUD

In a keynote address to the National Science Foun-

dation workshop on Critical Infrastructure Protection

for SCADA & IT, Dr. Arden Bement listed several

incidents to illustrate the vulnerability of SCADA

systems (NSF Workshop, 2003). He dismissed the

notion of “Obscurity” if we think SCADA systems

are highly customized, highly technical, and there-

fore the guys in the black hats won't be able to figure

them out in addition to the fact that 60 to 70 percent

of all industrial security breaches are carried out by

someone on the inside.

NSA lists a checklist on securing SCADA and

CS (Control Systems): Develop a Security Policy;

Establish Physical Security; Lockdown Perimeter

Security; Enable Existing Security Features; Secure

Operational Traffic; Secure Management Traffic;

Manage the CS Configuration; Eliminate Security

Shortfalls; Continuous Security Training; and Per-

form Security Audits Systems (SCADA and CS).

Developing a proper security policy set a founda-

tion for securing SCADA systems and its CS assets.

It defines and places controls in various stages. With

security policy in place, proper enforcement plays

crucial roles in securing SCADA systems. For ex-

ADAPTING SCADA SYSTEMS TO CLOUD COMPUTING ENVIRONMENT

561

ample, strict access control to SCADA should be

periodically reviewed. Cut off unnecessary connec-

tion to outside is essential.

One of the major issues with SCADA systems

are legacy devices and proprietary protocols that are

still in use. Although many of existing SCADA

equipments is quiet reliable, their support is more

and more difficulty due to the change in manufactur-

ing and the advance in technology. In addition,

many manufacturers have stopped supporting these

equipments that use proprietary protocols. Therefore

many system managers are anxious to upgrade their

SCADA systems. On one hand, it provides an op-

portunity for better data translation, data propagation

and data protection when companies start to upgrade

its devices in SCADA system to more standardized

ones. On the other hand, it also poses great potential

problems when legacy devices are used with these

newer devices. Not only are data translation and data

propagation not supported, performance and reliabil-

ity will suffer as well. System administrators often

fail to conduct proper risk analysis of their current

system and the implementation of any new technol-

ogy. Development of platforms that interact with

legacy systems and the modern SCADA network

help to create the synergy necessary to achieve an

efficient and reliable platform that has the ability to

give the security, reliability and adaptability.

When moving networked SCADA systems into

Cloud, we also need to develop checklists for audit-

ing that will provide a level of confidence of doing

things right and doing right things, just like we did

when we moved standalone SCADA systems to

networked SCADA systems.

Progress in the area of standardization is best

achieved by external organizations such as Interna-

tional Standards Organization (ISO), International

Federations of Information Processing Societies

(IFIPS), the Institute for Electric and Electronic

Engineers (IEEE), the International Communications

Associations (ICA), and other well respected and

recognized groups (Selig, 2003).

In the utilization of cloud services, the assump-

tion should be a predication that such cloud services

should show a level of reliable and security. The

goal of the designer should be to create a level of

security that will enable the system to remain secure

if any part of the system is compromised.

Some of the feature needed to create a more se-

cure SCADA cloud system can be summarized in

the table 1.

5 DISCUSSION

Moving networked SCADA systems to a public

cloud has many unanswered questions and poses

many security challenging. It is often controversial.

It is evident when we approached NY Metro North

Rail system. But, private cloud and even community

cloud is more acceptable. The project also assesses

existing SCADA equipments that are amazingly

Table 1: Securing Cloud SCADA Systems.

Auditing Internal auditing

External auditing

Data encryption VPN

PKI Systems

Physical Security Facilities

People

Environment

equipment

Software Security Trustworthy

Conformant

Predictability

Business Continuity and Disaster Recovery Continuity Planning

Identify Critical Business Function

Establish Recovery Time Objective

Network Security Establishing a Network Security Manage-

ment Team

Transmission Control

Connection Control

Quality of service Measurable metrics

Framework COSO

COBIT

ISO27001

ICEIS 2011 - 13th International Conference on Enterprise Information Systems

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reliable although outdated. It is in the process of

updating these equipments.

Recently, we see renewed interests in SCADA

systems. Not only are SCADA systems still used in

our national critical infrastructures such as power

grid, railway systems, gas pipelines and nuclear

power plants, but also the movement from isolated

systems to more open systems and lack of skilled

professionals. Research and training are both impor-

tant. Both NSA (National Security Agency) and

DHS (Department of Homeland Security) have

looked into our national SCADA systems, its vulne-

rability and weakness as well as protection mechan-

isms ((SCADA and CS; Testimony of Deputy Under

Secretary Philip Reitinger; Securing Industrial Con-

trol Systems in the Chemical Sector, 2011), for ex-

ample).

In summary, we should pay more attentions to

SCADA systems and the trend of upgrading. Proper

risk assessment should be done. Cloud computing

has huge potential in IT services. Incorporating both

should be able to deliver more efficient control sys-

tems.

REFERENCES

Securing Supervisory Control and Data Acquisition

(SCADA) and Control Systems (CS), http://

www.nsa.gov/ia/_files/factsheets/scada_factsheet.pdf

SCADA at http://en.wikipedia.org/wiki/SCADA

Protecting America's Critical Infrastructures: PDD 63

http://www.justice.gov/criminal/cybercrime/white_pr.

htm

Krutz R., Securing SCADA Systems, Wiely Publishing

Inc, 2006

NIST Definition of Cloud Computing v15, http://

csrc.nist.gov/groups/SNS/cloud-computing/cloud-def-

v15.doc

Security Guidance for Critical Areas of Focus in Cloud

Computing V2.1, by Cloud Security Alliance, Decem-

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csaguide.pdf

Chen, Z. and Yoon, J.: IT Auditing to Assure a Secure

Cloud Computing. The proceedings of the 6th IEEE

World Congress on Services, July 5-10, 2010, Miami,

Florida, USA, 253-259

http://en.wikipedia.org/wiki/Stuxnet for general descrip-

tion

Will Forrest, Clearing the Air on Cloud Computing, Dis-

cussion Document from McKinsey and Company,

March 2009

NIST Presentation on Effectively and Securely Using the

Cloud Computing Paradigm v26, accessed on

4/15/2010, http://csrc.nist.gov/groups/SNS/

cloud-computing/cloud-computing-v26.ppt

Open Security Architecture Group http://

www.opensecurityarchitecture.org/cms/library/patternl

andscape/251-pattern-cloud-computing

Vyatkin, V., et al, Toward Digital Ecologies: Intelligent

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structures, 1st IEEE Conference on Smart Grid Com-

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critical interface to critical infrastructures, the 5th In-

ternational Conference on Critical Infrastructure

(CRIS), 2010

Geberslassie, M.; Bitzer, B.; Future SCADA systems for

decentralized distribution systems, the 45th Interna-

tional Universities Power Engineering Conference

(UPEC), 2010

Communication in ACM, Virtualization is good for securi-

Bratus, S., Locasto M., Ramaswamy, A. and Smith

S.;VM-based security overkill: a lament for applied

systems security research, Proceedings of the 2010

workshop on New security paradigms, 51-60, 2010

The NSF Workshop on Critical Infrastructure Protection

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http://www.nist.gov/director/speeches/bement_102003

.cfm

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Protection, and Security Technologies, "Examining the

Cyber Threat to Critical Infrastructure and the Ameri-

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testimony_1300283858976.shtm)

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ing Council in partnership with the U.S. Department

of Homeland Security, April, 2011 (http://

www.dhs.gov/xlibrary/assets/oip-chemsec-case-for-

action-042011.pdf). Note, DHS has many relevant

documents related to the SCADA systems.

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