Network Security and Privacy

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Network Security and Privacy
CS 378

• Vitaly Shmatikov

http//www.cs.utexas.edu/shmat/courses/cs378_spri
ng05/
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Course Personnel

• Instructor Vitaly Shmatikov
• Office TAYLOR 4.115C
• Office hours Thursday, 330-430pm (after class)
• Open door policy dont hesitate to stop by!
• TA Justin Brickell
• Office hours TBA
• Watch the course website
• Assignments, reading materials, lecture notes
• This course is an experiment!
• First UT course on network security

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Prerequisites

• Required CS 372 (Operating Systems)
• My course has a substantial implementation
  component
• No waivers!
• Recommended Introduction to Computer Security
  Cryptography Computer Networks
• Not much overlap with this course, but will help
  gain deeper understanding of security mechanisms
  and where they fit in the big picture
• Recommended exposure to C programming
• Project will involve implementing buffer overflow
  exploits in C

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Class Poll

• Introduction to computer security?
• Access control, Web security, sandboxing,
  firewalls?
• Cryptography?
• Public-key and symmetric encryption, digital
  signatures, cryptographic hash, random-number
  generators?
• Computer networks?
• Network architecture, application and transport
  layer protocols?
• Programming in C?

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Course Logistics

• Lectures
• Tuesday, Thursday 2-330pm
• Five homeworks (40 of the grade)
• One or two may involve implementation
• Project (15 of the grade)
• Involves a fair bit of implementation
• Security is a contact sport!
• Midterm (20 of the grade)
• Final (25 of the grade)
• UTCS Code of Conduct will be strictly enforced

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Course Materials

• Textbook William Stallings. Network Security
  Essentials Applications and Standards.
• Focuses on details of deployed security systems
• Lectures will focus on big-picture principles
  and ideas of network attack and defense
• Attend lectures! Lectures will cover some
  material that is not in the textbook and you
  will be tested on it!
• Occasional assigned readings
• Start reading Smashing the Stack For Fun and
  Profit by Aleph One (from Phrack hacker
  magazine)
• Understanding it will be essential for your
  project

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Other Helpful Books

• Ross Anderson. Security Engineering.
• Focuses on design principles for secure systems
• Wide range of entertaining examples banking,
  nuclear command and control, burglar alarms
• Ross Anderson is famous for hacking
  tamper-resistant hardware
• Kaufman, Perlman, Speciner. Network Security
  Private Communication in a Public World.
• Comprehensive network security textbook

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Main Themes of the Course

• Vulnerabilities of networked applications
• Worms, denial of service attacks, malicious code
  arriving from the network, attacks on
  infrastructure
• Defense technologies
• Protection of information in transit
  cryptography, application- and transport-layer
  security protocols
• Protection of networked applications firewalls
  and intrusion detection
• Study a few deployed systems in detail from
  design principles to gory implementation details
• Kerberos, SSL/TLS, IPSec

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What This Course is Not About

• Not a comprehensive course on computer security
• Not a course on ethical, legal or economic issues
• No file sharing, DMCA, free speech issues
• Only cursory overview of cryptography
• Take CS 346 for deeper understanding
• Only some issues in systems security
• No access control, OS security, secure hardware
• Will cover buffer overflow 1 cause of remote
  penetration attacks
• No language-based security

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Motivation
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Excerpt From General Terms of Use
YOU ACKNOWLEDGE THAT NEITHER WELLS FARGO, ITS
AFFILIATES NOR ANY OF THEIR RESPECTIVE EMPLOYEES,
AGENTS, THIRD PARTY CONTENT PROVIDERS OR
LICENSORS WARRANT THAT THE SERVICES OR THE SITE
WILL BE UNINTERRUPTED OR ERROR FREE NOR DO THEY
MAKE ANY WARRANTY AS TO THE RESULTS THAT MAY BE
OBTAINED FROM USE OF THE SERVICES OR THE SITE, OR
AS TO THE TIMELINESS, SEQUENCE, ACCURACY,
RELIABILITY, COMPLETENESS OR CONTENT OF ANY
INFORMATION, SERVICE, OR MERCHANDISE PROVIDED
THROUGH THE SERVICES AND THE SITE.
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Privacy and Security

• As a Wells Fargo customer, your privacy and
  security always come first.
• Privacy policy for individuals
• Online privacy policy
• Our commitment to online security
• Online and computer security tips
• How we protect you
• General terms of use

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What Do You Think?

• What do you think should be included in
• privacy and security for an e-commerce website?
• ?

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Desirable Security Properties

• Authenticity
• Confidentiality
• Integrity
• Availability
• Non-repudiation
• Freshness
• Access control
• Privacy of collected information
• Integrity of routing and DNS infrastructure

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Syllabus (1) Security Mechanisms

• Basics of cryptography
• Symmetric and public-key encryption,
  certificates, cryptographic hash functions,
  pseudo-random generators
• Authentication and key establishment
• Case study Kerberos
• IP security
• Case study IPSec protocol suite
• Web security
• Case study SSL/TLS (Transport Layer Security)

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Syllabus (2) Attacks and Defenses

• Buffer overflow attacks
• Network attacks
• Distributed denial of service
• Worms and viruses
• Attacks on routing infrastructure
• Defense tools
• Firewalls and intrusion detection systems
• Wireless security
• Privacy-enhancing technologies

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Attack on Confidentiality

• Confidentiality is concealment of information

Eavesdropping, packet sniffing, illegal copying
network
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Attack on Integrity

• Integrity is prevention of unauthorized changes

Intercept messages, tamper, release again
network
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Attack on Authenticity

• Authenticity is identification and assurance of
  origin of information

Unauthorized assumption of anothers identity
network
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Attack on Availability

• Availability is ability to use information or
  resources desired

Overwhelm or crash servers, disrupt infrastructure
network
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Network Stack
email, Web, NFS
application
presentation
RPC
session
TCP
transport
IP
network
802.11
data link
physical
Only as secure as the single weakest layer
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Network Defenses
Implementations
Firewalls, intrusion detection
Systems
Protocols and policies
SSL, IPSec, access control
Blueprints
Cryptographic primitives
Building blocks
RSA, DSS, SHA-1
all defense mechanisms must work correctly and
securely
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Correctness versus Security

• Program or system correctness
• program satisfies specification
• For reasonable input, get reasonable output
• Program or system security
• program properties preserved in face of attack
• For unreasonable input, output not completely
  disastrous
• Main difference active interference from
  adversary
• Modular design may increase vulnerability
• Abstraction is very difficult to achieve in
  security what if the adversary operates below
  your level of abstraction?

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Bad News

• Security often not a primary consideration
• Performance and usability take precedence
• Feature-rich systems may be poorly understood
• Higher-level protocols make mistaken assumptions
• Implementations are buggy
• Buffer overflows are the vulnerability of the
  decade
• Networks are more open and accessible than ever
• Increased exposure, easier to cover tracks
• Many attacks are not even technical in nature
• Phishing, impersonation, etc.

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Better News

• There are a lot of defense mechanisms
• Well study some, but by no means all, in this
  course
• Its important to understand their limitations
• If you think cryptography will solve your
  problem, then you dont understand cryptography
  and you dont understand your problem -- Bruce
  Schneier
• Many security holes are based on misunderstanding
• Security awareness and user buy-in help
• Other important factors usability and economics

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Reading Assignment

• Stallings, sections 1.1-1.5
• Start reading buffer overflow materials on the
  website