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An Overview ofComputer Security

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Outline Components of computer security Threats Policies and mechanisms The role of trust Assurance Operational Issues Human Issues

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Status of security in computing (in early 2000s)

In terms of security, computing is very close to the wild west days.

Some computing professionals & managers do not even recognize the value of the resources they use or control.

In the event of a computing crime, some companies do not investigate or prosecute.

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Has the status changed for the better?

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Characteristics of Computer Intrusion A computing system: a collection of

hardware, software, data, and people that an organization uses to do computing tasks

Any piece of the computing system can become the target of a computing crime.

The weakest point is the most serious vulnerability.

The principles of easiest penetration

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Security Breaches- Terminology Exposure

– a form of possible loss or harm Vulnerability

– a weakness in the system Attack Threats

– Human attacks, natural disasters, errors Control – a protective measure Assets – h/w, s/w, data

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Types of Security Breaches Disclosure: unauthorized access to info

– Snooping Deception: acceptance of false data

– Modification, spoofing, repudiation of origin, denial of receipt

Disruption: prevention of correct operation

– Modification, man-in-the-middle attack

Usurpation: unauthorized control of some part of

the system (usurp: take by force or without right)– Modification, spoofing, delay, denial of service

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Security Components Confidentiality: The assets are accessible only by

authorized parties.– Keeping data and resources hidden

Integrity: The assets are modified only by authorized parties, and only in authorized ways.– Data integrity (integrity)– Origin integrity (authentication)

Availability: Assets are accessible to authorized parties.– Enabling access to data and resources

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Computing System Vulnerabilities Hardware vulnerabilities Software vulnerabilities Data vulnerabilities Human vulnerabilities ?

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Software Vulnerabilities Destroyed (deleted) software Stolen (pirated) software Altered (but still run) software

– Logic bomb– Trojan horse– Virus– Trapdoor– Information leaks

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Data Security

The principle of adequate protection Storage of encryption keys Software versus hardware methods

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Other Exposed Assets

Storage media Networks Access Key people

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People Involved in Computer Crimes

Amateurs Crackers Career Criminals

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Methods of Defense

Encryption Software controls Hardware controls Policies Physical controls

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Encryption

at the heart of all security methods Confidentiality of data Some protocols rely on encryption to

ensure availability of resources. Encryption does not solve all computer

security problems.

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Software controls

Internal program controls OS controls Development controls Software controls are usually the 1st

aspects of computer security that come to mind.

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Policies and Mechanisms Policy says what is, and is not, allowed

– This defines “security” for the site/system/etc.

Mechanisms enforce policies Mechanisms can be simple but effective

– Example: frequent changes of passwords

Composition of policies– If policies conflict, discrepancies may create

security vulnerabilities

Legal and ethical controls– Gradually evolving and maturing

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Principle of Effectiveness

Controls must be used to be effective.– Efficient

• Time, memory space, human activity, …

– Easy to use

– appropriate

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Overlapping Controls

Several different controls may apply to one potential exposure.

H/w control + S/w control + Data control

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Goals of Security Prevention

– Prevent attackers from violating security policy

Detection– Detect attackers’ violation of security policy

Recovery– Stop attack, assess and repair damage– Continue to function correctly even if attack

succeeds

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Trust and Assumptions

Underlie all aspects of security Trust and verify vs Verify before trust? Policies

– Unambiguously partition system states– Correctly capture security requirements

Mechanisms– Assumed to enforce policy– Support mechanisms work correctly

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Types of Mechanisms

secure precise broad

set of reachable states set of secure states

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Assurance

Specification– Requirements analysis– Statement of desired functionality

Design– How system will meet specification

Implementation– Programs/systems that carry out design

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Operational Issues

Cost-Benefit Analysis– Is it cheaper to prevent or to recover?

Risk Analysis– Should we protect something?– How much should we protect this thing?

Laws and Customs– Are desired security measures illegal?– Will people do them?

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Human Issues Organizational Problems

– Power and responsibility– Financial benefits

People problems– Outsiders and insiders– Social engineering

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“The methods that will most effectively minimize the ability of intruders to compromise information security are comprehensive user training and education. Enacting policies and procedures simply won't suffice. Even with oversight the policies and procedures may not be effective: my access to Motorola, Nokia, ATT, Sun depended upon the willingness of people to bypass policies and procedures that were in place for years before I compromised them successfully.” — Kevin Mitnick

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Tying Together

Threats

Policy

Specification

Design

Implementation

Operation

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Key Points Policy defines security, and

mechanisms enforce security– Confidentiality– Integrity– Availability

Trust and knowing assumptions Importance of assurance The human factor

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