Tuomas Aura T-110.4206 Information security technology
Lecture 1: Computer security overview
Aalto University, autumn 2012
Outline
Timeline of computer security
What is security anyway?
Summary
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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 4
80s
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 – Cellular networks: GSM 1991 – Open-source cryptography: PGP 1991 – Password sniffers SSH 1995 – Commercial Internet SSL and VeriSign CA 1995 – RSA patent expired in 2000
Spam: Cantor and Siegel 1994 PKI criticism trust management research User authentication beyond passwords Intrusion detection Macro virus: Melissa 1999 DRM
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2000s
Fast-spreading Internet worms: Code Red 2001 secure programming secure programming languages security analysis and testing tools
Botnets, spyware malware analysis
Computer crime: phishing
Enterprise identity management
Security in mobility, Grid, ah-hoc networks, sensor networks
Mobile device operating systems
Social networks, privacy concerns
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2010s
Cloud computing
Internet of Things
Cyberwar, critical infrastructure protection
App security
Vehicular communication
Mobile payments?
Smart grid security, home automation
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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
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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?
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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 regulation You cannot be just a security expert! Need broader understanding 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 prison 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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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 events are explained better by group behavior than rational choice
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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 defence
However, detection is needed to monitor the effectiveness of the technical prevention
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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 – Hackers, crackers, script kiddies — for challenge and reputation – Companies — for economic intelligence and marketing – Security agencies — NSA, FAPSI, GCHQ, DGSE, etc. – Military SIGINT — strategic and tactical intelligence, cyber war – Organized criminals — for money
Often, not all types of attackers matter – E.g. who would you not want to read your diary or email?
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Security research
Security research often focuses on attacks
Engineers should focus on solutions BUT need to understand – how systems fail
– how the attacker thinks
– adversarial mindset
Security researchers spend most of their time looking for flaws in the work of others not always welcomed by others; so be careful in how you talk about security
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Ethical considerations Who is allowed to attack and when?
– Violations of policy vs. actual damage
Are security policies for us or against us? – University policy vs. active learning – Difference between research or QA and crime? – Privacy of human subjects – Getting work done vs. following rules
Security is commonly used as an excuse for indecision and power grabs
Ethics and engineering: – What is your technology used for? – Is your product secure enough for release?
SUMMARY
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Security reseach methods
Access control in operating systems
Cryptography (encryption), authentication
Attacks, vulnerability analysis
Methods borrowed from other areas of IT: systems research, computer languages, networking, formal models and proofs
Connections to legislation, sosiology, psychology, management, design
Security is a non-functional feature of a system a security expert must also be an expert in the application area
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Goals of information security
Security goals: confidentiality and integrity of information, availability of services
Authentication, access control, accounting
Protection of services and infrastructure in a hostile environment (e.g. Internet)
Control, monitoring or privacy
Business continuity
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) and academic researchers differ?
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