Cyber Attacks Protecting National Infrastructure, 1st ed. Chapter 6 Depth Copyright © 2012, Elsevier Inc. All Rights Reserved 1 Introduction Anylayerofdefensecanfailatanytime,thusthe introduction of defense in depth Aseriesofprotectiveelementsisplacedbetweenan asset and the adversary Theintentistoenforcepolicyacrossallaccesspoints Copyright © 2012, Elsevier Inc. All rights Reserved 2 Chapter 6 – Depth Fig. 6.1 – General defense in depth schema Copyright © 2012, Elsevier Inc. All rights Reserved 3 Chapter 6 – Depth Effectiveness of Depth Quantifyingtheeffectivenessofalayereddefenseis often difficult Effectivenessisbestdeterminedbyeducatedguesses Thefollowingarerelevantforestimating effectiveness – Practical experience – Engineering analysis – Use-case studies – Testing and simulation Copyright © 2012, Elsevier Inc. All rights Reserved 4 Chapter 6 – Depth Fig. 6.2 – Moderately effective single layer of protection Copyright © 2012, Elsevier Inc. All rights Reserved 5 Chapter 6 – Depth Effectiveness of Depth • Whenalayerfails,wecanconcludeitwaseither flawed or unsuited to the target environment • Nolayeris100%effective—thegoalofmakinglayers “highly” effective is more realistic Copyright © 2012, Elsevier Inc. All rights Reserved 6 Chapter 6 – Depth Fig. 6.3 – Highly effective single layer of protection Copyright © 2012, Elsevier Inc. All rights Reserved 7 Chapter 6 – Depth Fig. 6.4 – Multiple moderately effective layers of protection Copyright © 2012, Elsevier Inc. All rights Reserved 8 Chapter 6 – Depth Layered Authentication Anationalauthenticationsystemforeverycitizen would remove the need for multiple passwords, passphrases, tokens, certificates, and biometrics that weaken security Singlesign-on(SSO)wouldaccomplishthis authentication simplification objective However,SSOaccessneedstobepartofa multilayered defense Copyright © 2012, Elsevier Inc. All rights Reserved 9 Chapter 6 – Depth Fig. 6.5 – Schema showing two layers of end-user authentication Copyright © 2012, Elsevier Inc. All rights Reserved 10 Chapter 6 – Depth Fig. 6.6 – Authentication options including direct mobile access Copyright © 2012, Elsevier Inc. All rights Reserved 11 Chapter 6 – Depth Layered E-Mail Virus and Spam Protection Commercialenvironmentsareturningtovirtual,in- the-cloud solutions to filter e-mail viruses and spam Tothatsecuritylayerisaddedfilteringsoftwareon individual computers Antivirussoftwarehelpful,butuselessagainstcertain attacks (like botnet) Copyright © 2012, Elsevier Inc. All rights Reserved 12 Chapter 6 – Depth Fig. 6.7 – Typical architecture with layered e-mail filtering Copyright © 2012, Elsevier Inc. All rights Reserved 13 Chapter 6 – Depth Layered Access Controls • Layeringaccesscontrolsincreasessecurity • Addtothisthelimitingofphysicalaccesstoassets • Fornationalinfrastructure,assetsshouldbecovered by as many l.

1. Cyber Attacks
Protecting National Infrastructure, 1st ed.
Chapter 6
Depth
Copyright © 2012, Elsevier Inc.
All Rights Reserved
1
Introduction
Anylayerofdefensecanfailatanytime,thusthe
introduction of
defense in depth
Aseriesofprotectiveelementsisplacedbetweenan
asset and the adversary
Theintentistoenforcepolicyacrossallaccesspoints
Copyright © 2012, Elsevier Inc.

2. All rights Reserved
2
Chapter 6 – Depth
Fig. 6.1 – General defense in depth schema
Copyright © 2012, Elsevier Inc.
All rights Reserved
3
Chapter 6 – Depth
Effectiveness of Depth
Quantifyingtheeffectivenessofalayereddefenseis often difficult
Effectivenessisbestdeterminedbyeducatedguesses
Thefollowingarerelevantforestimating
effectiveness
– Practical experience
– Engineering analysis

3. – Use-case studies
– Testing and simulation
Copyright © 2012, Elsevier Inc.
All rights Reserved
4
Chapter 6 – Depth
Fig. 6.2 – Moderately effective single layer of protection
Copyright © 2012, Elsevier Inc.
All rights Reserved
5
Chapter 6 – Depth
Effectiveness of Depth
• Whenalayerfails,wecanconcludeitwaseither
flawed
or
unsuited

4. to the target environment
• Nolayeris100%effective—thegoalofmakinglayers “highly”
effective is more realistic
Copyright © 2012, Elsevier Inc.
All rights Reserved
6
Chapter 6 – Depth
Fig. 6.3 – Highly effective single layer of protection
Copyright © 2012, Elsevier Inc.
All rights Reserved
7
Chapter 6 – Depth
Fig. 6.4 – Multiple moderately effective layers of protection
Copyright © 2012, Elsevier Inc.
All rights Reserved

5. 8
Chapter 6 – Depth
Layered Authentication
Anationalauthenticationsystemforeverycitizen would remove the
need for multiple passwords, passphrases, tokens, certificates,
and biometrics that weaken security
Singlesign-on(SSO)wouldaccomplishthis authentication
simplification objective
However,SSOaccessneedstobepartofa multilayered defense
Copyright © 2012, Elsevier Inc.
All rights Reserved
9
Chapter 6 – Depth
Fig. 6.5 – Schema showing two layers of end-user
authentication
Copyright © 2012, Elsevier Inc.

6. All rights Reserved
10
Chapter 6 – Depth
Fig. 6.6 – Authentication options including direct mobile access
Copyright © 2012, Elsevier Inc.
All rights Reserved
11
Chapter 6 – Depth
Layered E-Mail Virus and Spam Protection
Commercialenvironmentsareturningtovirtual,in- the-cloud
solutions to filter e-mail viruses and spam
Tothatsecuritylayerisaddedfilteringsoftwareon individual
computers
Antivirussoftwarehelpful,butuselessagainstcertain attacks (like
botnet)
Copyright © 2012, Elsevier Inc.

7. All rights Reserved
12
Chapter 6 – Depth
Fig. 6.7 – Typical architecture with layered e-mail filtering
Copyright © 2012, Elsevier Inc.
All rights Reserved
13
Chapter 6 – Depth
Layered Access Controls
• Layeringaccesscontrolsincreasessecurity
• Addtothisthelimitingofphysicalaccesstoassets
• Fornationalinfrastructure,assetsshouldbecovered by as many
layers possible
– Network-based firewalls – Internal firewalls
– Physical security

8. Copyright © 2012, Elsevier Inc.
All rights Reserved
14
Chapter 6 – Depth
Fig. 6.8 – Three layers of protection using firewall and access
controls
Copyright © 2012, Elsevier Inc.
All rights Reserved
15
Chapter 6 – Depth
Layered Encryption
• Fiveencryptionmethodsfornationalinfrastructure protection
– Mobile device storage – Network transmission
– Secure commerce
– Application strengthening
– Server and mainframe data storage

9. Copyright © 2012, Elsevier Inc.
All rights Reserved
16
Chapter 6 – Depth
Fig. 6.9 – Multple layers of encryption
Copyright © 2012, Elsevier Inc.
All rights Reserved
17
Chapter 6 – Depth
Layered Intrusion Detection
Thepromiseoflayeredintrusiondetectionhasnot been fully
realized, though it is useful
Theinclusionofintrusionresponsemakesthe layered approach
more complex
Therearethreeopportunitiesfordifferentintrusion detection
systems to provide layered protection

10. – In-band detection
– Out-of-band correlation – Signature sharing
Copyright © 2012, Elsevier Inc.
All rights Reserved
18
Chapter 6 – Depth
Fig. 6.10 – Sharing intrusion detection information between
systems
Copyright © 2012, Elsevier Inc.
All rights Reserved
19
Chapter 6 – Depth
National Program of Depth
• Developingamultilayereddefensefornational infrastructure
would require a careful architectural analysis of all assets and
protection systems

11. – Identifying assets
– Subjective estimations
– Obtaining proprietary information – Identifying all possible
access paths
Copyright © 2012, Elsevier Inc.
All rights Reserved
20
Chapter 6 – Depth