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Guest Editor's Introduction: The Challenge of Building Survivable Information-Intensive Systems

Anita , University of Virginia

Pages: pp. 39-43

Abstract—Large and complex information systems permeate society's infrastructure. Vulnerable to attack and failure, these systems are built upon fragile embedded hardware and software. The research and the programs described here attempt to address these issues.

Information systems are now integrated into the fabric of every complex system that supports advanced society. They permeate society's infrastructures: Telecommunications, the electric grid, banking and financial services, manufacturing, surface transportation, petroleum delivery, and emergency services provide just a few examples. Over the past few decades, such systems have become increasingly automated. Their ability to operate now depends on ubiquitous, embedded information subsystems, both large and small.

Our information-intensive infrastructures suffer from two new vulnerabilities. First, they can be attacked by hackers, ideologues, terrorists, and organized crime.

Second, systems have become fragile. Centrally administered infrastructure systems that use highly distributed computing systems have reduced costs, increased efficiency, and allowed massive reductions of field personnel. Consequently, the built-in fault tolerance and backup manual operating modes made possible by field personnel are now degraded or gone. New modes, functions, and services operate at electronic, not manual speeds. Cybercomponents may even act to advance damage when it occurs, reducing opportunity for manual reaction. Deregulation further complicates the problem. It moves control from government-regulated monopolies to multiple private corporations, hindering a nation's ability to arrest widespread disruption with a coordinated response.

We have coined a new phrase, critical infrastructure protection, to describe a new concern. In 1996, US President Bill Clinton convened the President's Commission on Critical Infrastructure Protection. The Commission's purpose was to conduct a comprehensive review and recommend a national policy for protecting critical infrastructures and assuring their continued operation. In 1997, the Commission reported that "waiting for disaster is a dangerous strategy" 1 and called for immediate and comprehensive action.

Subsequently, Clinton issued Presidential Decision Directive 63 (PDD-63) in 1998. 2 This directive reflected many of the Commission's recommendations and established the Critical Infrastructure Assurance Office (CIAO) and the National Infrastructure Protection Center (NIPC) described in the accompanying sidebars. It also initiated agency-wide programs such as the DoD's Defense-Wide Infrastructure Assurance Program (DIAP).

We are also concerned about the survivability of information-only systems, even the survivability of your PC and mine. But the more significant problem lies with information systems integrated into the infrastructures that control a physical system's behavior.

Building survivable information-intensive systems is a deep concern for computer scientists and engineers. Although the problem derives from our past success, it painfully shows us how much further our research must progress. Our vulnerable systems arose from a lack of needed research in architectural design, computer security, reliability, and fault tolerance. To date, investment in such research has been too low.

Yet engineers have long worked to assure the survivability of complex systems—both before and after they became information intensive. Ignoring the embedded information subsystems, many survivability concerns arise from physics or the antics of Mother Nature. For example, failures arise from metal corrosion, wire insulation meltdowns, or unexpected temperature extremes. In these cases, deterioration is not typically instantaneous, but incremental as it moves through predictable states.

Information systems introduce two new and fundamentally hard problems. First, a one-bit change may not result in an incremental adaptation of the system, but may put it in a dramatically different state that can be viewed as discontinuous. Second, a thinking adversary, not physics or weather, may be involved. The adversary seeks weak links and exploits them. These two properties make building survivable information-intensive systems more difficult and a basic research problem.

The Presidential Commission called for a fourfold increase in the federal government's investment in research and development. While some recommendations—such as immediate changes in government processes and development of infrastructure systems patches—have been addressed, the agencies that should seek a true solution to this problem through basic research have regrettably not done so—despite this goal being a priority for the President. Because we are not progressing as fast as we could, it is highly likely that some portion of our society will needlessly incur grave consequences before researchers find and apply the fundamental solutions.

Furthermore, given the new global economy, critical infrastructure is not a specifically national issue—infrastructure issues have become transnational in character.


The critical challenge of assuring that we will have survivable systems led Computer's editors to dedicate this issue to the topic, presenting articles that approach the problem from quite different perspectives. Consequently, the solutions proposed for guaranteeing the survivability of systems, as well as for understanding and managing complexity through modeling and simulation, differ too.

Electric power grid

Massoud Amin's "Toward Self-Healing Infrastructure Systems" examines national infrastructures as complex interactive networks. He provides examples of the stresses being placed upon our power, telecommunications, transportation, and other infrastructures as well as potential external threats to them. For example, the August 1996 cascading power blackout in 11 US states and two Canadian provinces resulted from faults in a 500-kilovolt line in Oregon that generated excess load and tripped generators at McNary Dam. This, in turn, caused 500-milliwatt oscillations that separated the North-South-Pacific Intertie near the California-Oregon border. Experts now believe that shedding 0.4 percent of total load on the network for 30 minutes would have prevented the cascading effects, but load shedding is not typically a first-response option.

The Electric Power Research Institute (EPRI) is exploring ways of building "intelligence" into the electrical power infrastructure so that real-time analysis can be applied to the electric grid network to take proactive, self-stabilizing actions. Network components must mitigate and localize the effects of local failures and, if that fails, play an appropriate part in coordinated global reactions.

EPRI is developing intelligent electronic devices that combine sensors, computers, telecommunications units, and actuators to monitor and control the network, detect the system's true dynamics, predict a priori what kinds of problems may arise from specific failure types, take stock of options to mitigate prospective failures, and take action.

EPRI has played a leadership role in this area for some time, collaborating with the Department of Defense to fund long-term university research on complex interactive networks and systems. Such a partnership was arranged under the Government Industry Collaborative University Research project, and today DoD and EPRI equally fund a five-year, $30 million program, with funded university work already under way.

Next-Generation Internet

Users who run mission-critical applications on the Internet will require functionality unlikely to be available on the Next-Generation Internet. Some critical networked applications, glued together from component systems, exploit aspects of physical or logical separation. Although each application was designed independently, when integrated these systems lose that separation. Potentially, some assumptions about physical or logical isolation no longer hold, compromising rationales about safety properties. We thus need some notion of isolation that can be relied on for applications in shared network settings.

In his "The Next-Generation Internet: Unsafe at Any Speed?" Kenneth P. Birman introduces two case studies to illustrate the problem: intensive-care computing and integrated modular avionics. He proposes a new networking isolation capability, a virtual overlay network, which offers a basis for assuring reliability and security properties of critical applications. Birman points out that virtual overlay networks would be prohibitively costly to implement using contemporary technologies. He argues, however, that they can be supported at low cost and with good scalability, simply by extending an existing router feature and coupling it with well-understood group communication techniques.

Survivable information storage

As society becomes increasingly reliant upon digital information, information system users must be able to store their critical information with utmost confidence. They must be assured of their stored information's integrity, confidentiality, and continuous availability. For a storage system to be viewed as survivable, it must provide these guarantees over time. This unavoidably requires the replication and distribution of data and services across many storage nodes, because some subset of them may ultimately be (maliciously) compromised.

To meet this need, Jay J. Wylie and colleagues propose their PASIS architecture, described in "Survivable Information Storage Systems." Starting with the assumption that no individual service, node, or user can be fully trusted, they combine extant technologies with techniques for decentralizing storage services using threshold schemes, redundantly partitioning data, and performing dynamic self-maintenance.

Going after the bad guys

Donald E. Brown and colleagues' "Interactive Analysis of Computer Crimes" takes a different tack from the preceding articles. It describes the application of data analysis methods to link and associate computer crimes and to develop profiles of computer criminals based on incident data. More important, they extend this data analysis methodology with multiagent models that predict the behavior of computer criminals. While the databases they work with today relate mainly to conventional crime, it is appropriate to begin to develop the tools and techniques to profile computer criminal behavior and to simulate possible attacks that relate suspicious events across time and space.

Learning how to build survivable systems is laudable. But it is prudent to develop the techniques to detect and take action against those who attack our systems.


Some people question whether real problems can or even should drive basic research. The challenge of building survivable information-intensive systems is an excellent example of a very real problem whose only solution is research. By Presidential directive, every US Government agency has a highly visible team working on its particular instance of the problem. But the ultimate solution is not patches, filters, watchdog monitors, replicated systems, manual procedures, more security classification, and disconnection from networks. It lies in finding fundamentally new system architectures; identifying new and better approaches to assure security, reliability, and fault tolerance; and inventing new ways to make systems self-aware in a way that they have not been in the past. Although the articles in this issue make a contribution, assuring the survivability of information-intensive systems remains a worthy research challenge.

Critical Infrastructure Assurance Office

President Clinton signed Presidential Decision Directive 63 on 22 May 1998. PDD-63 created the Critical Infrastructure Assurance Office (CIAO), whose basic mission is to coordinate national planning activities related to critical infrastructure protection, develop awareness in the private and public sectors of the need for sound security practices, and support the development of a public-private partnership through outreach and other activities.

In January 2000, CIAO produced a National Plan for Information Systems Protection. This document is the first attempt by any nation to develop a plan to defend its cyberspace. The first version of the plan (subtitled "Version 1.0") largely focuses on the domestic efforts being undertaken by the federal government to protect the nation's critical cyber-based infrastructures. Subsequent versions of the plan will incorporate a broader range of concerns contemplated under PDD-63. These concerns include the specific role that industry and state and local governments will play—on their own and in partnership with the federal government—in protecting privately owned infrastructures; the need to protect both physical and cyber-based infrastructures from deliberate attack; and the examination of the international aspects of critical infrastructure protection. Comments by industry, Congress, state and local governments, and the general public are sought for improvements that could be included in these subsequent versions.

The Bureau of Export Administration is the CIAO's parent agency. BXA seeks to enhance the nation's security and its economic prosperity by controlling exports for national-security, foreign policy, and short-supply reasons. BXA seeks to support the defense industrial base and assists US defense firms that have been affected by reduced defense spending. BXA helps other countries develop export control systems comparable to ours and has assisted enterprises in the republics of the former Soviet Union in converting to civil production.

For more information, visit


National Infrastructure Protection Center

The National Infrastructure Protection Center's (NIPC) mission at the FBI involves both a national-security and law-enforcement effort to detect, deter, assess, warn of, respond to, and investigate computer intrusions and unlawful acts, both physical and cyber, that threaten or target critical infrastructures.

Organized into six divisions, the NIPC is headed by a director who oversees two deputy directors. The two deputy directors are, in turn, responsible for three divisions: computer investigations and operations section (CIOS); analysis and warning section (AWS); and training, outreach, and strategy section (TOSS).

  • CIOS coordinates and supports computer intrusion investigations conducted by the 56 FBI Field Offices, providing technological support to investigations that involve computers and information technologies. CIOS also manages a Cyber Emergency Support Team, which helps respond to cyberattacks on critical infrastructures. In addition, CIOS provides and coordinates investigative and technological support to cyber investigators from other federal, state, or local government agencies.
  • AWS analyzes and assesses foreign and domestic threats, exploited vulnerabilities, and exploitation techniques concerning physical and cyber risks to the US's critical infrastructures. AWS provides direct analytical support for computer investigations and serves as the information clearinghouse for research and analysis of unlawful acts on the nation's infrastructures. Charged with obtaining relevant real-time information from all sources, AWS polls law enforcement investigations, intelligence sources, open sources, and voluntarily provided industry data, then analyzes and disseminates the information to relevant consumers in government and private sectors. The division also provides a watch-and-warning function to help alert other government agencies and private-sector companies to impending and ongoing attacks.
  • TOSS coordinates the training and continuing education of cyber investigators in FBI Field Offices, other federal agencies, and state and local law enforcement. The division also trains and educates personnel in the public and private sector who are involved in infrastructure protection. TOSS directs outreach efforts to FBI Field Offices, other government agencies, industry, and academia. These efforts are necessary to encourage information sharing about foreign and domestic threats, vulnerabilities, and technological developments. In addition, TOSS provides administrative support to the NIPC.

For more information, visit


DoD DIAP: Defense-Wide Information Assurance Program

Information assurance has become the Department of Defense's second-highest-priority issue, with only Y2K having been a higher concern. DoD depends increasingly on a commercially based global information environment over which it has little control, thereby increasing the department's exposure and vulnerability to a rapidly growing number of sophisticated internal and external threats. Today's internetworked information systems make it possible for an adversary to surreptitiously disrupt many systems, networks, and users by gaining access to a single network connection. Once inside a system, an adversary can exploit it and the systems networked to it.

The Defense-Wide Information Assurance Program, established in January 1998, is part of the Office of the Secretary of Defense. It is responsible for planning, monitoring, coordinating, and integrating IA activities. The DIAP acts as a facilitator for program execution by the commanders-in-chief (CINCs), military services, and defense agencies. The DIAP staff combines functional and programming skills for a comprehensive defense-wide approach to IA. The staff's continuous development and analysis of IA programs and functions will provide a "big picture" of the department's IA posture that identifies redundancies, incompatibilities, and general shortfalls in IA investments, and monitors deficiencies in resources and functional and operational capabilities.

The DIAP concentrates on eight areas:

  • Readiness assessments provide data needed to accurately assess IA readiness within the planning, programming, and budgeting systems. Focus areas include IA requirements identification and generation; vulnerability and threat analysis and assessment; and defense-wide standards and readiness reporting systems.
  • Human resources aims to supply sufficient adequately trained and educated personnel to conduct IA functions throughout the department. HR focuses on human resources development; education, training, and awareness; and manpower.
  • Policy integration provides for consistent implementation of IA-related policies throughout the department. Focus areas include national security and federal government and DoD IA policies and priorities.
  • Security management provides for the incorporation of appropriate security services, which allows and promotes global interoperability while preserving legitimate law-enforcement and national-security purposes. Security management focuses on key management, such as the public key infrastructure or electronic key management system; workstation security, such as operational systems and applications; virtual private networks, such as firewalls and guards; and tools and security management applications, such as network mapping and visualization.
  • Operational environment monitors enterprise information systems to provide continuous visibility of the department's IA operational readiness postures. This area focuses on network management, intrusion detection, incident response, defensive information operations, and attack sensing and warning.
  • Architectural standards and system transformation addresses integrating IA technologies, products, and support for procedures in the department's information technologies and information systems. This area focuses on enterprise-wide standards, implementation and incremental improvement, modernization of migration systems, survivability of common infrastructures, accreditation and readiness standards, multilevel security, and embedded IA capabilities.
  • Acquisition support and product development improves the department's IA readiness through disciplined, performance-based investments in security-enabled IT acquisitions. Focus areas include development of IA-related acquisition guidance; integration of mission statements and operational requirements documents; review of departmental protection profiles; identification of technology, product, and acquisition trends and the development of strategies for dealing with those trends; and product, evaluation, validation, and integration guidance.
  • Research and technology provides for the research and development of IA technologies and techniques consistent with current and anticipated DoD mission needs and changes in information technologies. Focus areas include leveraging DoD, government, commercial, and academic research; anticipating new technologies; developing synchronized IA solutions; and leveraging existing research coordination activities.

For more information, visit



About the Authors

Anita Jones is the Quarles Professor of Engineering and Applied Science in the Computer Science Department at the University of Virginia. She served as the director of Defense Research and Engineering at the Department of Defense from 1993 to 1997 and is currently vice chair of the National Science Board.Contact her at
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