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Chapter 3

Separation

Cyber Attacks Protecting National Infrastructure, 1st ed.

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• Using a firewall to separate network assets from intruders is the most familiar approach in cyber security

• Networks and systems associated with national infrastructure assets tend to be too complex for firewalls to be effective

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Introduction

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• Three new approaches to the use of firewalls are necessary to achieve optimal separation – Network-based separation

– Internal separation

– Tailored separation

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Introduction

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Fig. 3.1 – Firewalls in simple and complex networks

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• Separation is a technique that accomplishes one of the following – Adversary separation

– Component distribution

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What Is Separation?

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• A working taxonomy of separation techniques: Three primary factors involved in the use of separation – The source of the threat

– The target of the security control

– The approach used in the security control

(See figure 3.2)

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What Is Separation?

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Fig. 3.2 – Taxonomy of separation techniques

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• Separation is commonly achieved using an access control mechanism with requisite authentication and identity management

• An access policy identifies desired allowances for users requesting to perform actions on system entities

• Two approaches – Distributed responsibility

– Centralized control

– (Both will be required)

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Functional Separation?

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Fig. 3.3 – Distributed versus centralized mediation

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• Firewalls are placed between a system or enterprise and an un-trusted network (say, the Internet)

• Two possibilities arise – Coverage: The firewall might not cover all paths

– Accuracy: The firewall may be forced to allow access that inadvertently opens access to other protected assets

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National Infrastructure Firewalls

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Fig. 3.4 – Wide area firewall aggregation and local area firewall

segregation

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• Increased wireless connectivity is a major challenge to national infrastructure security

• Network service providers offer advantages to centralized security – Vantage point: Network service providers can see a lot

– Operations: Network providers have operational capacity to keep security software current

– Investment: Network service providers have the financial wherewithal and motivation to invest in security

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National Infrastructure Firewalls

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Fig. 3.5 – Carrier-centric network-based firewall

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• Network-based firewall concept includes device for throttling distributed denial of service (DDOS) attacks

• Called a DDOS filter

• Modern DDOS attacks take into account a more advanced filtering system

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DDOS Filtering

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Fig. 3.6 – DDOS filtering of inbound attacks on target assets

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• SCADA – Supervisory control and data acquisition

• SCADA systems – A set of software, computer, and networks that provide remote coordination of control system for tangible infrastructures

• Structure includes the following – Human-machine interface (HMI)

– Master terminal unit (MTU)

– Remote terminal unit (RTU)

– Field control systems

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SCADA Separation Architecture

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Fig. 3.7 – Recommended SCADA system firewall architecture

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• Why not simply unplug a system’s external connections? (Called air gapping)

• As systems and networks grow more complex, it becomes more likely that unknown or unauthorized external connections will arise

• Basic principles for truly air-gapped networks: – Clear policy

– Boundary scanning

– Violation consequences

– Reasonable alternatives

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Physical Separation

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Fig. 3.8 – Bridging an isolated network via a dual-homing user

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• Hard to defend against a determined insider

• Threats may also come from trusted partners

• Background checks are a start

• Techniques for countering insider attack – Internal firewalls

– Deceptive honey pots

– Enforcement of data markings

– Data leakage protection (DLP) systems

• Segregation of duties offers another layer of protection

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Insider Separation

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Fig. 3.9 – Decomposing work functions for segregation of duty

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• Involves the distribution, replication, decomposition, or segregation of national assets – Distribution: creating functionality using multiple

cooperating components that work together as distributed system

– Replication: copying assets across components so if one asset is broken, the copy will be available

– Decomposition: breaking complex assets into individual components so an isolated compromise won’t bring down asset

– Segregation: separation of assets through special access controls, data markings, and policy enforcement

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Asset Separation

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Fig. 3.10 – Reducing DDOS risk through CDN-hosted content

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• Typically, mandatory access controls and audit trail hooks were embedded into the underlying operating system kernel

• Popular in the 1980s and 1990s

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Multilevel Security (MLS)

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Fig. 3.11 – Using MLS logical separation to protect assets

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• Internet separation: Certain assets simply shouldn’t be accessible from the Internet

• Network-based firewalls: These should be managed by a centralized group

• DDOS protection: All assets should have protection in place before an attack

• Internal separation: Critical national infrastructure settings need an incentive to implement internal separation policy

• Tailoring requirements: Vendors should be incentivized to build tailored systems such as firewalls for special SCADA environments

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National Separation Program

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Chapter 6

Depth

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• Any layer of defense can fail at any time, thus the introduction of defense in depth

• A series of protective elements is placed between an asset and the adversary

• The intent is to enforce policy across all access points

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Introduction

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Fig. 6.1 – General defense in depth schema

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• Quantifying the effectiveness of a layered defense is often difficult

• Effectiveness is best determined by educated guesses

• The following are relevant for estimating effectiveness – Practical experience

– Engineering analysis

– Use-case studies

– Testing and simulation

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Effectiveness of Depth

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Fig. 6.2 – Moderately effective single layer of protection

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• When a layer fails, we can conclude it was either flawed or unsuited to the target environment

• No layer is 100% effective—the goal of making layers “highly” effective is more realistic

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Effectiveness of Depth

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Fig. 6.3 – Highly effective single layer of protection

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Fig. 6.4 – Multiple moderately effective layers of protection

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• A national authentication system for every citizen would remove the need for multiple passwords, passphrases, tokens, certificates, and biometrics that weaken security

• Single sign-on (SSO) would accomplish this authentication simplification objective

• However, SSO access needs to be part of a multilayered defense

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Layered Authentication

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Fig. 6.5 – Schema showing two layers of end-user authentication

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Fig. 6.6 – Authentication options including direct mobile access

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Layered E-Mail Virus and Spam Protection

• Commercial environments are turning to virtual, in- the-cloud solutions to filter e-mail viruses and spam

• To that security layer is added filtering software on individual computers

• Antivirus software helpful, but useless against certain attacks (like botnet)

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Fig. 6.7 – Typical architecture with layered e-mail filtering

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• Layering access controls increases security

• Add to this the limiting of physical access to assets

• For national infrastructure, assets should be covered by as many layers possible – Network-based firewalls

– Internal firewalls

– Physical security

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Layered Access Controls

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Fig. 6.8 – Three layers of protection using firewall and access controls

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• Five encryption methods for national infrastructure protection – Mobile device storage

– Network transmission

– Secure commerce

– Application strengthening

– Server and mainframe data storage

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Layered Encryption

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Fig. 6.9 – Multple layers of encryption

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• The promise of layered intrusion detection has not been fully realized, though it is useful

• The inclusion of intrusion response makes the layered approach more complex

• There are three opportunities for different intrusion detection systems to provide layered protection – In-band detection

– Out-of-band correlation

– Signature sharing

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Layered Intrusion Detection

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Fig. 6.10 – Sharing intrusion detection information between systems

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• Developing a multilayered defense for national infrastructure would require a careful architectural analysis of all assets and protection systems – Identifying assets

– Subjective estimations

– Obtaining proprietary information

– Identifying all possible access paths

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National Program of Depth

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Chapter 2

Deception

Cyber Attacks Protecting National Infrastructure, 1st ed.

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Introduction

• Deception is deliberately misleading an adversary by creating a system component that looks real but is in reality a trap – Sometimes called a honey pot

• Deception helps accomplish the following security objectives – Attention

– Energy

– Uncertainty

– Analysis

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• If adversaries are aware that perceived vulnerabilities may, in fact, be a trap, deception may defuse actual vulnerabilities that security mangers know nothing about.

Introduction

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Fig. 2.1 – Use of deception in computing

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Introduction

• Four distinct attack stages: – Scanning

– Discovery

– Exploitation

– Exposing

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Fig. 2.2 – Stages of deception for national infrastructure protection

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• Adversary is scanning for exploitation points – May include both online and offline scanning

• Deceptive design goal: Design an interface with the following components – Authorized services

– Real vulnerabilities

– Bogus vulnerabilities

• Data can be collected in real-time when adversary attacks honey pot

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Scanning Stage

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Fig. 2.3 – National asset service interface with deception

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• Deliberately inserting an open service port on an Internet-facing server is the most straightforward deceptive computing practice

• Adversaries face three views

– Valid open ports

– Inadvertently open ports

– Deliberately open ports connected to honey pots

• Must take care the real assets aren’t put at risk by bogus ports

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Deliberately Open Ports

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Fig. 2.4 – Use of deceptive bogus ports to bogus assets

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Fig. 2.5 – Embedding a honey pot server into a normal server complex

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• The discovery stage is when an adversary finds and accepts security bait embedded in the trap

• Make adversary believe real assets are bogus – Sponsored research

– Published case studies

– Open solicitations

• Make adversary believe bogus assets are real – Technique of duplication is often used for honey pot

design

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Discovery Stage

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Fig. 2.6 – Duplication in honey pot design

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• Creation and special placement of deceptive documents can be used to trick an adversary (Especially useful for detecting a malicious insider) – Only works when content is convincing and

– Protections appear real

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Deceptive Documents

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Fig. 2.7 – Planting a bogus document in protected enclaves

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• This stage is when an adversary exploits a discovered vulnerability – Early activity called low radar actions

– When detected called indications and warnings

• Key requirement: Any exploitation of a bogus asset must not cause disclosure, integrity, theft, or availability problems with any real asset

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Exploitation Stage

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Fig. 2.8 – Pre- and post-attack stages at the exploitation stage

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• Related issue: Intrusion detection and incident response teams might be fooled into believing trap functionality is real. False alarms can be avoided by – Process coordination

– Trap isolation

– Back-end insiders

– Process allowance

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Exploitation Stage

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• Understand adversary behavior by comparing it in different environments.

• The procurement lifecycle is one of the most underestimated components in national infrastructure protection (from an attack perspective)

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Procurement Tricks

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Fig. 2.9 – Using deception against malicious suppliers

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• The deception lifecycle ends with the adversary exposing behavior to the deception operator

• Therefore, deception must allow a window for observing that behavior – Sufficient detail

– Hidden probes

– Real-time observation

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Exposing Stage

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Fig. 2.10 – Adversary exposing stage during deception

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Interfaces Between Humans and Computers

• Gathering of forensic evidence relies on understanding how systems, protocols, and services interact – Human-to-human

– Human-to-computer

– Computer-to-human

– Computer-to-computer

• Real-time forensic analysis not possible for every scenario

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Fig. 2.11 – Deceptively exploiting the human-to-human interface

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• Programs for national deception would be better designed based on the following assumptions: – Selective infrastructure use

– Sharing of results and insights

– Reuse of tools and methods

• An objection to deception that remains is that it is not effective against botnet attacks – Though a tarpit might degrade the effectiveness of a

botnet

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Chapter 8

Collection

Cyber Attacks Protecting National Infrastructure, 1st ed.

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• Diligent and ongoing observation of computing and networking behavior can highlight malicious activity – The processing and analysis required for this must be done

within a program of data collection

• A national collection process that combines local, regional, and aggregated data does not exist in an organized manner

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Introduction

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Fig. 8.1 – Local, regional, and national data collection with aggregation

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• At local and national levels data collection decisions for national infrastructure should be based on the following security goals – Preventing an attack

– Mitigating an attack

– Analyzing an attack

• Data collection must be justified (who is collecting and why)

• The quality of data is more important than the quantity

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Fig. 8.2 – Justification-based decision analysis template for data collection

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• Metadata is perhaps the most useful type of data for collection in national infrastructure – Metadata is information about data, not what the data is

about

• Data collection systems need to keep pace with growth of carrier backbones

• Sampling data takes less time, but unsampled data may be reveal more

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Collecting Network Data

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Fig. 8.3 – Generic data collection schematic

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Fig. 8.4 – Collection detects evidence of vulnerability in advance of notification

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• National initiatives have not traditionally collected data from mainframes, servers, and PCs

• The ultimate goal should be to collect data from all relevant computers, even if that goal is beyond current capacity

• System monitoring may reveal troubling patterns

• Two techniques useful for embedding system management data – Inventory process needed to identify critical systems

– Process of instrumenting or reusing data collection facilities must be identified

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Collecting System Data

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Fig. 8.5 – Collecting data from mainframes, servers, and PCs

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Security Information and Event Management

• Security information and event management (SIEM) is the process of aggregating system data from multiple sources for purpose of protection

• Each SIEM system (in a national system of data collection) would collect, filter, and process data

• Objections to this approach include both the cost of setting up the architecture and the fact that embedded SIEM functionality might introduce problems locally

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Fig. 8.6 – Generic SIEM architecture

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Fig. 8.7 – Generic national SIEM architecture

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• Identifying trends is the most fundamental processing technique for data collected across the infrastructure

• Simplest terms – Some quantities go up (growth)

– Some quantities go down (reduction)

– Some quantities stay the same (leveling)

– Some quantities doing none of the above (unpredictability)

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Large-Scale Trending

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Fig. 8.8 – Growth trend in botnet behavior over 9-month period (2006–

2007)

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• Some basic practical considerations that must be made by security analysts before a trend can be trusted – Underlying collection

– Volunteered data

– Relevant coverage

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Large-Scale Trending

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• Collecting network metadata allows security analysts track a worm’s progress and predict its course

• Consensus holds that worms work too fast for data collection to be an effective defense – There’s actually some evidence that a closer look at the

data might provide early warning of worm threats

• After collecting and analyzing, the next step is acting on the data in a timely manner

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Tracking a Worm

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Fig. 8.9 – Coarse view of UDP traffic spike from SQL/Slammer worm

(Figure courtesy of Dave Gross and Brian Rexroad)

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Fig. 8.10 – Fine view of UDP traffic spike from SQL/Slammer worm (Figure courtesy of Dave Gross and Brian Rexroad)

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• Once the idea for a national data collection program is accepted, the following need to be addressed – Data sources

– Protected transit

– Storage considerations

– Data reduction emphasis

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National Collection Program

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Chapter 5

Commonality

Cyber Attacks Protecting National Infrastructure, 1st ed.

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• Certain security attributes must be present in all aspects and areas of national infrastructure to ensure maximum resilience against attack

• Best practices, standards, and audits establish a low- water mark for all relevant organizations

• Audits must be both meaningful and measurable – Often the most measurable things aren’t all that

meaningful

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Introduction

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• Common security-related best practices/standards – Federal Information Security Management Act (FISMA)

– Health Insurance Portability and Accountability Act (HIPAA)

– Payment Card Industry Data Security Standard (PCI DSS)

– ETSI Cyber Security Technical Committee (TC-CYBER)

– ISO/IEC 27000 Standard family (ISO27K) • ISO 27001 – Security management systems

• ISO 27002 – Code of practice for InfoSec controls

– COBIT - Control Objectives for Information and related Technology

– NIST Cybersecurity Framework

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Introduction

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Fig. 5.1 – Illustrative security audits for two organizations

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Fig. 5.2 – Relationship between meaningful and measurable

requirements

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• The primary motivation for proper infrastructure protection should be success based and economic – Not the audit score

• Security of critical components relies on – Step #1: Standard audit

– Step #2: World-class focus

• Sometimes security audit standards and best practices proven through experience are in conflict

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Meaningful Best Practices for Infrastructure Protection

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Fig. 5.3 – Methodology to achieve world-class infrastructure

protection practices

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• Four basic security policy considerations are recommended – Enforceable: Policies without enforcement are not

valuable

– Small: Keep it simple and current

– Online: Policy info needs to be online and searchable

– Inclusive: Good policy requires analysis in order to include computing and networking elements in the local nat’l infrastructure environment

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Locally Relevant and Appropriate Security Policy

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Fig. 5.4 – Decision process for security policy analysis

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• Create an organizational culture of security protection

• Culture of security is one where standard operating procedures provide a secure environment

• Ideal environment marries creativity and interest in new technologies with caution and a healthy aversion to risk

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Culture of Security Protection

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Fig. 5.5 – Spectrum of organizational culture of security options

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• Organizations should be explicitly committed to infrastructure simplification

• Common problems found in design and operation of national infrastructure – Lack of generalization

– Clouding the obvious

– Stream-of-consciousness design

– Nonuniformity

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Infrastructure Simplification

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Fig. 5.6 – Sample cluttered engineering chart

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Fig. 5.7 – Simplified engineering chart

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• How to simplify a national infrastructure environment – Reduce its size

– Generalize concepts

– Clean interfaces

– Highlight patterns

– Reduce clutter

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Infrastructure Simplification

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• Key decision-makers need certification and education programs

• Hundred percent end-user awareness is impractical; instead focus on improving security competence of decision-makers – Senior Managers

– Designers and developers

– Administrators

– Security team members

• Create low-cost, high-return activities to certify and educate end users

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Certification and Education

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Fig. 5.8 – Return on investment (ROI) trends for security education

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• Create and establish career paths and reward structures for security professionals

• These elements should be present in national infrastructure environments – Attractive salaries

– Career paths

– Senior managers

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Career Path and Reward Structure

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• Companies and agencies being considered for national infrastructure work should be required to demonstrate past practice in live security incidents

• Companies and agencies must do a better job of managing their inventory of live incidents

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Responsible Past Security Practice

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• Companies and agencies being considered for national infrastructure work should provide evidence of the following past practices – Past damage

– Past prevention

– Past response

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Responsible Past Security Practice

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• A national commonality plan involves balancing the following concerns – Plethora of existing standards

– Low-water mark versus world class

– Existing commissions and boards

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National Commonality Program

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Chapter 4

Diversity

Cyber Attacks Protecting National Infrastructure, 1st ed.

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Introduction

• The securing any set of national assets should include a diversity strategy

• The deliberate introduction of diversity into national infrastructure to increase security has not been well explored

• Two system are considered diverse if their key attributes differ

• Diversity bucks the trend to standardize assets for efficiency's sake

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Fig. 4.1 – Diverse and nondiverse components through attribute

differences

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Diversity and Worm Propagation

• Worm propagation is an example of an attack that relies on a nondiverse target environment

• Worm functionality in three steps: – Step #1: Find a target system on the network for

propagation of worm program

– Step #2: Copy program to that system

– Step #3: Remotely execute program

– Repeat

• Diversity may be expensive to introduce, but saves money on response costs in the long run

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Fig. 4.2 – Mitigating worm activity through diversity

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Desktop Computer System Diversity

• Most individual computers run the same operating system software on a standard processor platform and browse the Internet through one or two popular search engines with the one of only a couple browsers

• The typical configuration is a PC running Windows on an Intel platform, browsing the Internet with Internet Explorer, searching with Google

• This makes the average home PC user a highly predictable target

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Fig. 4.3 – Typical PC configuration showing diversity

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Desktop Computer System Diversity

• Three Considerations – Platform costs

– Application interoperability

– Support and training

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• Ultimate solution for making desktops more secure involves their removal – Not a practical solution

• Cloud computing may offer home PC users a diverse, protected environment

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Diversity Paradox of Cloud Computing

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Fig. 4.4 – Spectrum of desktop diversity options

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Fig. 4.5 – Diversity and attack difficulty with option of removal

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• Modern telecommunications consist of the following two types of technologies – Circuit-switched

– Packet-switched

• When compared to one another, these two technologies automatically provide diversity

• Diversity may not always be a feasible goal – Maximizing diversity may defend against large-scale

attacks, but one must also look closely at the entire architecture

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Network Technology Diversity

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Fig. 4.6 – Worm nonpropagation benefit from diverse telecommunications

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Fig. 4.7 – Potential for impact propagation over shared fiber

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• Any essential computing or networking asset that serves a critical function must include physical distribution to increase survivability

• Physical diversity has been part of the national asset system for years – Backup center diversity

– Supplier/vendor diversity

– Network route diversity

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Physical Diversity

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Fig. 4.8 – Diverse hubs in satellite SCADA configurations

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• A national diversity program would coordinate between companies and government agencies – Critical path analysis

– Cascade modeling

– Procurement discipline

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National Diversity Program

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Chapter 7

Discretion

Cyber Attacks Protecting National Infrastructure, 1st ed.

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• Proprietary information will be exposed if discovered by hackers

• National infrastructure protection initiatives most prevent leaks – Best approach: Avoid vulnerabilities in the first place

– More practically: Include a customized program focused mainly on the most critical information

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Introduction

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• A trusted computing base (TCB) is the totality of hardware, software, processes, and individuals considered essential to system security

• A national infrastructure security protection program will include – Mandatory controls

– Discretionary policy

• A smaller, less complext TCB is easier to protect

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Trusted Computing Base

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Fig. 7.1 – Size comparison issues in a trusted computing base

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• Managing discretion is critical; questions about the following should be asked when information is being considered for disclosure – Assistance

– Fixes

– Limits

– Legality

– Damage

– Need

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Trusted Computing Base

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• Security through obscurity is often maligned and misunderstood by security experts – Long-term hiding of vulnerabilities

– Long-term suppression of information

• Security through obscurity is not recommended for long-term protection, but it is an excellent complementary control – E.g., there’s no need to publish a system’s architecture

– E.g., revealing a flaw before it’s fixed can lead to rushed work and an unnecessary complication of the situation

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Security Through Obscurity

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Fig. 7.2 – Knowledge lifecycle for security through obscurity

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Fig. 7.3 – Vulnerability disclosure lifecycle

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• Information sharing may be inadvertent, secretive, or willful

• Government most aggressive promoting information sharing

• Government requests information from industry for the following reasons – Government assistance to industry

– Government situational awareness

– Politics

• Government and industry have conflicting motivations

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Information Sharing

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Fig. 7.4 – Inverse value of information sharing for government and industry

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• Adversaries regularly scout ahead and plan before an attack

• Reconnaissance planning levels – Level #1: Broad, wide-reaching collection from a variety of

sources

– Level #2: Targeted collection, often involving automation

– Level #3: Directly accessing the target

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Information Reconnaissance

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Fig. 7.5 – Three stages of reconnaissance for cyber security

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• At each stage of reconnaissance, security engineers can introduce information obscurity

• The specific types of information that should be obscured are – Attributes

– Protections

– Vulnerabilities

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Information Reconnaissance

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• Layering methods of obscurity and discretion adds depth to defensive security program

• Even with layered obscurity, asset information can find a way out – Public speaking

– Approved external site

– Search for leakage

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Obscurity Layers

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Fig. 7.6 – Obscurity layers to protect asset information

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• Governments have been successful at protecting information by compartmentalizing information and individuals – Information is classified

– Groups of individuals are granted clearance

• Compartmentalization defines boundaries, which helps guides decisions

• Private companies can benefit from this model

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Organizational Compartments

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Fig. 7.7 – Using clearances and classifications to control information

disclosure

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Fig. 7.8 – Example commercial mapping of clearances and classifications

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• To implement a national discretion program will require – TCB definition

– Reduced emphasis on information sharing

– Coexistence with hacking community

– Obscurity layered model

– Commercial information protection models

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National Discretion Program

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