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Infrastructure resilience

Ian Sommerville

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Resilience• Resilience is the ability of assets,

networks and systems to anticipate, absorb, adapt to, and recover from a disruptive event or series of events.

• Resilience is about maintaining the continuity of a service in the presence of disruptive events

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Pandemic disease

• Pandemic disease is the highest impact risk because it potentially affects the whole of a national infrastructure as people become ill

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Cyber attacks

• Cyber attacks that compromise confidentiality are not likely to have a major impact on the availability of a national infrastructure

• But cyber attacks that affect the control systems are more serious

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Risk impact

• Risk impact is related to the extent of the damage to infrastructure assets

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Impact depends on locality

• Local incidents, such as a terrorist attack on physical infrastructure, have limited impact because they only affect a small part of that infrastructure

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Organisational infrastructure

• Organisations may be more vulnerable than physical infrastructure

• Incidents that affect the organisational infrastructure can have more significant impact

– Organisations are less likely to be distributed

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Risk impact

• Because physical infrastructure is distributed, failures in one part of a physical network are localised

– A crack is discovered in one bridge but this does not affect other bridges in the network

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Software vulnerability

• However, software control changes this

– If common elements of an infrastructure are networked and controlled by the same software, a failure in one element (especially a malicious attack) can propagate throughout the network

– Large-scale failures and unavailability therefore become possible

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Infrastructure dependencies• All infrastructure

elements now depend on power and communications

• Failure and unavailable of these infrastructures has the most impact

Photo: creative commons/flickr/anemoneprojectors

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Infrastructure vulnerabilities

• Limited physical protection

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Infrastructure vulnerabilities

• Old/insecure software control systems

Image: http://commons.wikimedia.org/wiki/File:SCADA_PUMPING_STATION_1.jpg

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Infrastructure vulnerabilities

• Lack of monitoring systems

• Lack of coordination across infrastructure elements

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Infrastructure vulnerabilities

• Lack of knowledge of infrastructure state or dependencies

• Lack of knowledge of infrastructure demand

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Achieving resilience

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Resistance

Provide protection against anticipated events or attacks

– Flood defences

– Cybersecurity awareness

© Adrian Pingstone 2005

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Resistance

• Based on previous experience and assumptions

• Changing world or external circumstances may mean that assumptions are invalid

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Reliability

• Infrastructure components should be designed to operate under a range of (anticipated) conditions not just ‘normal’ operating conditions

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Reliability

• Components, as far as possible, should be designed for ‘soft’, incremental rather than catastrophic failure

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Digital and analog systems

• Digital systems are more brittle than analog systems

• Analog systems often fail gradually; computer-based systems often simply crash

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Redundancy

• The network or system as a whole should be designed so that there are backup installations and spare capacity available.

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Redundancy

• Examples– Computing support should be provided by

different providers in different locations

– Diverse generation capacity for electricity

– Multiple locations for command and control

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Response and recovery

• Respond to distruptive events quickly, limiting the damage as far as possible and ensuring public safety

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Response and recovery

• Plan how to restore services as quickly as possible in the event of a loss of capability

• Business continuity planning

• Disaster recovery

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Achieving resilience• Advance planning to draw up contingency

plans to cover anticipated problems

• (a) good design of the network and systems to ensure it has the necessary resistance, reliability and redundancy (spare capacity), and

• (b) by establishing good organisational resilience to provide the ability, capacity and capability to respond and recover from disruptive events.

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Key points• Critical infrastructure resilience is the

ability of the infrastructure to continue to deliver essential services during and after a hazardous event

• Infrastructure resilience depends on planning for contingencies and effective infrastructure design

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Key points• Software control of infrastructure

systems potentially increases vulnerability because the effects of an event may not be localised

• Resilient infrastructure design is based on 4 R’s – resistance, reliability, redundancy, and recovery