Computer security overview

Tuomas AuraCSE-C3400 Information security

Aalto University, autumn 2014

Outline

Timeline of computer security

What is security anyway?

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TIMELINE OF COMPUTER SECURITY

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70s Multi-user operating systems need for protection

Access control models: multi-level security, Bell-LaPadula 1976, BIBA 1977

DES encryption algorithm 1976 cryptanalysis, need for key distribution

Public-key cryptosystems:Diffie-Hellman 1976, RSA 1978

Key distribution: certificates 1978 key exchange protocols: Needham-Schroeder 1978

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80s

Anonymity, Chaum’s mixes 1981, anonymous payment 1982

Orange Book 1985: mandatory access control

Commercial security models from accounting and auditing rules: Clark-Wilson 1987

X.509 PKI 1988

IBM PC software copy protection floppy disk virus 1987

Internet Morris worm 1988

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90s More methodological approach to security research:

Information flow security Secure operating systems: SEVMS until 1996 Formal analysis of key exchange protocols

Wider availability of cryptography – GSM cellular network 1991– Open-source cryptography: PGP 1991– Password sniffers SSH 1995– Commercial Internet SSL and VeriSign CA 1995– RSA patent expired in 2000

Windows 95 insecure PCs connected to Internet Spam: Cantor and Siegel 1994 PKI criticism trust management research Research intrusion detection Macro virus: Melissa 1999 DRM

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2000s Malware

– Fast-spreading Internet worms: Code Red 2001 secure programming, safe languages security analysis and testing tools

– Botnets, spyware, malware analysis

Computer crime: phishing Total information awareness 2002- Mobile device operating systems, app permissions Enterprise identity management Research on security in mobility, ah-hoc networks, sensor networks Security has become integral part of most areas of computing and

computer science Connections to law, sociology, psychology, management, usability,

design Social networks, privacy concerns

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2010s

Cyber defense and attack– Stuxnet 2010, malware business, government sponsors– Snowden 2013, PRISM (2007-)– Advanced persistent threat

Flaws still found in key security technologies: Heartbleed 2014, fake SSL certificates

Critical infrastructure protection, smart grid security Mobile app security, cloud computing Mobile payments Bitcoin, ransomware Research on Internet of Things, vehicular

communication What else?

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WHAT IS SECURITY

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What is security When talking about security, we are concerned

about bad events caused with malicious intent – Security vs. reliability

Terminology:– Threat = bad event that might happen– Attack = someone intentionally causes the bad thing to

happen– Vulnerability = weakness in an information system that

enables an attack– Exploit = implementation of an attack– Risk = probability of an attack × damage in dollars

Security is a non-functional property of a system

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Security Goals

CIA = confidentiality, integrity, availability

– Confidentiality — protection of secrets

– Integrity — only authorized modification of data and system configuration

– Availability — no denial of service, business continuity

Examples: secret agent names, web server

The CIA model is a good starting point but not all:

– Access control — no unauthorized use of resources

– Privacy — control of personal data and space

– What else?

Some other goals

Authentication for access control

Accounting, payment

Content protection

Protection of services and infrastructure in a hostile environment (e.g. Internet)

Control and monitoring

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Areas of IT security[Gollmann] Computer security — security of end hosts and

client/server systems– Focus: access control in operating systems– Example: access control lists for file systems

Network security — security of communication– Focus: protecting data on the wire– Example: encryption to prevent sniffing

Application security — security of services to end users and businesses– Focus: application-specific trust relations– Example: secure and legally binding bank transactions

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Viewpoints to security Cryptography (mathematics) Computer security (systems research) Network security (computer networking) Software security (software engineering, programming

languages and tools) Formal methods for security (theoretical CS) Hardware security (HW engineering) Human aspects of security (usability, sociology) Security management (information-systems management,

enterprise security) Economics of security, laws and regulationYou cannot be just a security expert! Need broaderunderstanding of the systems and applications

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Security is a continuous process Continuous race between attackers and defenders

– Attackers are creative

No security mechanisms will stop all attacks; attackers just move to new methods and targets– Some types of attacks can be eliminated but others will

take their place– Compare with crime statistics: Do locks or prisons reduce

crime in the long term?

Security mechanisms will fail and new threats will arise→ Monitoring and auditing for new attacks→ Contingency planning: how to recover from a breach

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Proactive vs. reactive security Technical prevention: design systems to prevent,

discourage and mitigate attacks– If attack cannot be prevented, increase its cost and

control damage Detection and reaction: detect attacks and take

measures to stop them, or to punish the guilty In open networks, attacks happen all the time

– We can detect port scans, spam, phishing etc., yet can do little to stop it or to punish attackers

→ Technical prevention and mitigation must be the primary defense

However, detection is needed to monitor the effectiveness of the technical prevention

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Cost vs. benefit Rational attackers compare the cost of an attack with

the gains from it– Attackers look for the weakest link; thus, little is gained by

strengthening the already strong bits

Rational defenders compare the risk of an attack with the cost of implementing defenses– Lampson: “Perfect security is the enemy of good security”

But human behavior is not always rational:– Attackers follow each other and flock all to the same path

– Defenders buy a peace of mind; avoid personal liability by doing what everyone else does

→ Many things are explained better by group behavior than rational choice

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Who is the attacker? We partition the world into good and bad entities

– Honest parties vs. attackers, red vs. blue– Good ones follow specification, bad ones do not– Different partitions lead to different perspectives on the security of the

same system

Typical attackers:– Curious or dishonest individuals — for personal gain– Friends and family– Hackers, crackers, script kiddies — for challenge and reputation– Companies — for business intelligence and marketing– Organized criminals — for money– Governments and security agencies — NSA, SVR, GCHQ, DGSE, etc.– Military SIGINT — strategic and tactical intelligence, cyber defense

Insiders are often the greatest threat– Employee, administrator, service provider, customer, family member

Often, not all types of attackers matter– Who would you not want to read your diary or email?

Reading material

Dieter Gollmann: Computer Security, 2nd ed. chapters 1–2; 3rd ed. chapters 1 and 3

Matt Bishop: Introduction to computer security, chapter 1 (http://nob.cs.ucdavis.edu/book/book-intro/intro01.pdf)

Edward Amoroso: Fundamentals of Computer Security Technology, chapter 1

Ross Anderson: Security Engineering, 2nd ed., chapter 1 (1st ed. http://www.cl.cam.ac.uk/~rja14/Papers/SE-01.pdf)

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Exercises What security threats and goals are there in the postal (paper mail)

system?– What different entities are there in the postal system?– Do they have the same of different security concerns?– Who could be the attacker? Does the answer change if you think from

a different entity’s viewpoint? Who are insiders?– Can you think of attacks where it is necessary for two or more

malicious parties to collude?

What is the role of laws and punishment in computer security? Can the development of information security technology be

unethical, or is engineering value neutral? Give examples. When is it (or when could it be) ok for you to attack against IT

systems? Give examples. How do the viewpoints of security practitioners (e.g. system admin

or company security officer) differ from academic researchers? How have the Snowden leaks in 2013 changed the overall picture of

information security?

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