1. Critical infrastructure
Critical infrastructure, 2013 Slide 1

2. What is infrastructure
• All modern societies and
businesses are dependent upon
an underlying infrastructure:
power, water, waste disposal,
the internet, transport networks,
financial services, emergency
services, hospitals etc.
• This infrastructure is shared by
all elements of business and
society
Critical infrastructure, 2013 Slide 2

3. Critical systems of systems
• Why is this being covered in a computer science
course on critical systems:
– Our infrastructure is controlled and managed by a wide range
of interacting, computer-based system
– Businesses and essential services to citizens are completely
dependent on our ‘digital infrastructure’
– Therefore, all of the systems involved in infrastructure
management are critical systems
• We cannot consider these critical systems in isolation
but must also consider their interactions. We are
therefore concerned with critical systems of systems
Critical infrastructure, 2013 Slide 3

4. Public infrastructure
• The national infrastructure
comprises networks,
systems, sites, facilities
and businesses that
deliver goods and services
to citizens, and support
our economy, environment
and social well-being.
• Includes systems and
services such as
transport, energy,
computing,
communications, finance,
health care, etc.
Critical infrastructure, 2013 Slide 4

5. Organisational infrastructure
• Supply chain and external
information systems on
which an organisation
depends
• Digital infrastructure within
the organisation
(servers, networks, etc.)
• Shared business services
such as accounting and
purchasing
Critical infrastructure, 2013 Slide 5

6. Infrastructure characteristics
Large Scale
• Spread over large geographic areas
• Regional/National/International
– Complex
• Many components
• Many interdependencies (internal and external)
– Reliance on standards
• Heterogeneous parts rely on standards for interoperation
• Standards are not always uniformly applied across an infrastructure
– Long term
• Modern and legacy components
• Emerges and changes over the long term
• We have to live with decisions made a long time ago
Critical infrastructure, 2013 Slide 6

7. Digital infrastructure
• Hardware and software
systems and networks on
which businesses and
society depends
– Fibre communication links
– Mobile phone and data network
– Data centres and servers
– ISPs
• Now, almost universally,
other infrastructure
components depend on the
Critical infrastructure, 2013
digital infrastructure to deliver
Slide 7
their services

8. Infrastructure ownership
• Rarely one single owner and
authority
• Sub-systems and components
are increasingly privatised
– The theory is that privately
operated infrastructure will be
more efficient
– However it is difficult to optimise
an infrastructure when sections of
it are run by self interested
parties
• Crosses national and
Critical infrastructure, 2013 international boundaries Slide 8

9. Infrastructure funding
• Infrastructure replacement is
very expensive
• We (and governments) are
often reluctant to pay for
infrastructure
• Where monopolies exist
they are able to over-
charge.
• However, competition
where operational costs are
low can lead to under-
Critical infrastructure, 2013 charging (and no re- Slide 9

10. Critical infrastructure
• Assets which are part of the national and
organisational infrastructure whose availability is
essential to the delivery of infrastructure services
and whose unavailability has significant human,
social and economic consequences.
• Critical infrastructure includes
– Structures
– Networks
– Systems
– Organisations
Critical infrastructure, 2013 Slide 10

11. Landline Phones
Mobile Telecommunications Production
Postal Services Processing
Communications Import
Broadcast Communications
Distribution
Food Retail
Ambulance
Fire and Rescue Electricity
Emergency Services
Marine Gas Payment, Clearing
Police Oil and Settlement
Energy
Fuel Systems
Public Finances
Finance Markets and
Central Government
Exchanges
Parliament
Government
Devolved Administrations
Regional and Local Authorities
Health Maritime
Health and Social Care Aviation
Transport Land (Road and rail)
Potable water supply
Water Dams
Waste Water
Critical infrastructure, 2013 Services Slide 11

12. Critical assets
• Not all components of
the national
infrastructure are critical
• Does not just depend on
the type of facility but
also on the number of
people affected or other
consequences of
unavailability
– London Heathrow airport
is a critical asset
– Dundee Airport is not a
Critical infrastructure, 2013 critical asset Slide 12

13. Infrastructure dependencies
• Infrastructure
elements are often
dependent on each
other so that failure of
one element may be
caused by failure of
some other element
elsewhere
Internet services delivered by an ISP depend on communication
services from a telecomms company and power from an electricity
company
Critical infrastructure, 2013 Slide 13

14. Understanding dependencies
• Functional: Reliance between components.
• Informational: Data flow from one node aides decision making
elsewhere.
• Shared Control: Control is from the same system/location
• Geospatial: Physical proximity
• Purpose: A shared function or purpose
• Policy/procedural: A change in policy or procedure at one place
may have effects elsewhere.
• Societal Interdependency: Changes to one component may
have societal effects which lead to changes to others
Critical infrastructure, 2013 Slide 14

15. Cascade failure
• A failure in one area cascades to another
infrastructure sector, causing failures and
disruption, sometimes in quite unrelated areas
• Failure of flood defences results in an electricity sub-
station being flooded
• Leads to a loss of power in the local area
• An ISP in that area goes offline, leading to a loss of
internet service to customers who may be anywhere
in the country.
Critical infrastructure, 2013 Slide 15

16. Mutual dependencies
• Mutual dependencies
cause major problems in
the event of failure
• Example
– Communications systems
depend on power
– Power recovery depends on
communications
– Power failure that leads to
loss of comms is difficult to
recover from
Critical infrastructure, 2013 Slide 16

17. Single point of failure
• Several services share
some facility so that
failure at that facility
leads to a loss of all of
these services.
• Examples
– Power and
communication cables
http://www.flickr.com/photos/brizo_th in the same duct
e_scot/3736542522/
– Transport, communicati
on, power use the
same bridge to cross a
river
Critical infrastructure, 2013 Slide 17

18. Protecting and assuring
infrastructure
A difficult problem
– Infrastructure is rarely under individual control
– Infrastructure is large scale
• Assurance takes place through governance processes and risk
management
– Identify key components
– Identify vulnerabilities
– Identify threats
– Construct risk models
– Assess possible outcomes from loss
– Make/request/lobby for necessary improvements
– Make contingency plans
Critical infrastructure, 2013 Slide 18

19. Infrastructure threats
Critical infrastructure, 2013 Slide 19

20. Vulnerabilities
• Lack of knowledge of infrastructure state and
dependencies
• Old, insecure systems used for infrastructure control
• Capacity planning based on outdated assumptions
• Geographically distributed infrastructure cannot be
physically secured
• Lack of coordinated infrastructure management
• Physical location of some facilities (flood plain)
Critical infrastructure, 2013 Slide 20

21. Infrastructure resilience
Critical infrastructure, 2013 Slide 21

22. Resistance
• Provide protection
against anticipated
events or attacks
• Based on previous
experience and
assumptions
• Changing world or
external circumstances
may mean that
assumptions are invalid
Critical infrastructure, 2013 Slide 22

23. Reliability
• Infrastructure components
should be designed to
operate under a range of
(anticipated) conditions not
just ‘normal’ operating
conditions
• Components, as far as
possible, should be
designed for
‘soft’, incremental rather
than catastrophic failure
Critical infrastructure, 2013 Slide 23

24. Redundancy
• The network or system
as a whole should be
designed so that there
are backup installations
and spare capacity
available.
• Computing support
should be provided by
different providers in
different locations
Critical infrastructure, 2013 Slide 24

25. Response and recovery
• Respond to
distruptive events
quickly, limiting the
damage as far as
possible and
ensuring public
safety
• Plan how to restore
services as quickly
as possible in the
event of a loss of
capability
Critical infrastructure, 2013 Slide 25

26. Key points
• Infrastructure is critical to business, security, health,
society.
• We are increasingly reliant on digital infrastructure.
• Infrastructure is large scale, complex, has modern
and legacy components, and many
interdependencies.
• Securing infrastructure is a hard problem
• Hard to know what you have
• Hard to assess vulnerabilities
• Difficult to make improvements because infrastructure is
Critical infrastructure, 2013
rarely under direct control of those it is critical to Slide 26