IS 302: Information Security and Trust
Week 1: Introduction to IST, Security, and
Networks
2013
Course material
– My web site
– eLearn
© Yingjiu Li 2005
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Basic Modules
Background (1 week)
Applied
Crypto
(4 wks)
Network
Security
(4 wks)
Access
Control
(1 wk)
Project Presentations
(2 wk)
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Information Security & Trust
Security in Computing:
International Edition
Author: Charles P. Pfleeger
Shari Lawrence Pfleeger
Edition: 4th edition
ISBN: 9780136012962
Available in your
school bookshop!
Grading
•
Individual Assignment (10%)
–
–
•
Group Project (25%)
–
–
–
–
•
•
Presentation (15%) + report (10%)
Outline due in week 9 (Friday)
Presentation in weeks 12 and 13 (15%)
Final report due in week 14 (10%)
Midterm Quiz (15%; week 7)
Final Exam (40%; week 15)
–
•
Assignment 1(week 3)
Assignment 2 (week 10)
SMU final exam policy: Students are not allowed to
reschedule their examination or request for special
arrangements of the examination from instructors.
Attendance and Participation (10%)
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Policies
• Honor code
– No plagiarism or cheating (SMU Code of Student
Conduct)
• Due time (assignments, project, quiz, exam)
– Strictly enforced
– Points (~10%) may be deducted for late turn-in
• Excuses
– No excuse for project, midterm quiz, and final exam
– Must be approved before hand
• Class arrangement
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Introduction to Networks
Network Architecture
Host A
Host B
App A
App A
App B
App B
Subnet 2
Subnet 1
Router
Internet
Robert Deng/SMU
Link Level
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The Internet Protocol Layers
Apps
TCP/UDP
Host A
Host B
TCP/UDP
IP
IP
D-Link
D-Link
Physical
Apps
Internet
Physical
IP datagram/packet
Src IP Adr; Des IP Adr
IP header
Src Port#; Des Port#
TCP/UDP header
Robert Deng/SMU
Payload
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Terminology
• IP Address: An Internet identifier for each
network interface (Address of a building)
– Example: 202.161.41.246
• Port Number: An identifier for an application in a
host (Room number in a building)
• Hostname: An Internet name of a host (Name of a
building)
– Example: www.smu.edu.sg
• Domain name: An identifier of a domain, which is
a network of associated hosts
– Example: smu.edu.sg
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Router
• The postman in the Internet
– stores and forwards IP packets
• On arrival of an IP packet, it makes a
routing decision based on the packet’s
destination IP address.
• Routing decision: to choose the next router
to forward the packet, based on a routing
table
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Domain Name System (DNS)
A service translating “Names” to “IP addresses”
local DNS server
4. 74.125.79.105
1. www.google.com
ns01.staff.smu.edu.sg
authoritative DNS server
dns.google.com
www.google.com
your laptop
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Transport services and protocols
Host A
• Provide logical communication
between app processes running
on different hosts
• Transport protocols run in end
systems
– sending side: breaks app
messages into segments,
passes to network
– receiving side: reassembles
segments into messages,
passes to applications
• More than one transport protocol
available to apps
– Internet: TCP and UDP
application
TCP/UDP
network
data link
physical
network
data link
physical
network
data link
physical
network
data link
physical
network
data link
physical
network
data link
physical
application
TCP/UDP
network
data link
physical
Host B
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Internet Transport Layer Protocols
application
TCP/UDP
network
data link
physical
• Reliable, in-order
delivery (TCP)
– connection setup
network
data link
physical
network
data link
physical
network
data link
physical
• Unreliable, unordered
delivery: UDP
• Services not available:
network
data link
physical
network
data link
physical
application
TCP/UDP
network
data link
physical
– delay guarantees
– bandwidth guarantees
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Port Number
• Port: identity of an application
• IP address + port number can uniquely identify an
application running in a host in the Internet.
• Well-known Port numbers:
–
–
–
–
Web: TCP port 80
Email Transportation: TCP port 25
Email Retrieval: TCP port 110
DNS: UDP port 53
• Both the client and the server need to specify their
port numbers for data transmission.
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HTTP overview
HTTP has nothing to do with
how a web page is interpreted
HTTP: hypertext transfer
protocol
• Web’s application layer protocol
PC running
Explorer
• client/server model
– client: browser that requests,
receives, “displays” Web
objects
Server
running
Apache Web
server
– server: Web server sends
objects in response to requests
• HTTP 1.0: RFC 1945
Mac running
Navigator
• HTTP 1.1: RFC 2068
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Server:
• always on
• fixed address
Electronic Mail
Three major components:
• User agents
• Mail servers
• Simple mail transfer protocol:
SMTP
user
agent
user mailbox
mail
server
SMTP
User Agent
• “mail reader”
• Composing, editing, reading mail
messages
• e. g., Eudora, Outlook, elm,
Netscape Messenger
• Outgoing, incoming messages
stored on server
outgoing
message queue
SMTP
mail
server
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user
agent
SMTP
user
agent
user
agent
mail
server
user
agent
user
agent
Mathematic Notation
• x mod n, where x and n are natural numbers
– means the remainder of x divided by n
– e.g. 111 mod 879 equals to 111,
– e.g. 8913 mod 2 equals to 1
• x=y (mod n)
– means that x and y are congruent to n
– in other words, x and y have the same remainder when divided by n.
– e.g. 8913=8927 (mod 2)
• x-1 mod n
– means the
inverse of x with respect to n or mod n,
– Namely, xx-1 =1 (mod n)
– this is NOT 1/x !!!!!
– e.g. 3-1 mod 5 = 2, because 2*3=6 =1 (mod 5)
-1 mod 15= 4, because 4*4 = 16=1 (mod 15)
e.g. 4You
Good–news:
are not required to compute the modular
inverse.
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© Yingjiu Li 2005
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Motivation
• To fight against cybercrime
• I can attack U
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Achieve CIA
AVAILABILITY
CONFIDENTIALITY
INTEGRITY
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Objectives
• Confidentiality (secrecy, privacy)
– Information is not exposed to unauthorized
parties.
• Integrity
– Information is not modified by unauthorized
parties.
• Availability
– Information can be accessed by authorized
parties at proper time.
© Yingjiu Li 2005
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CIA-U
USAGE
CONFIDENTIALITY
AVAILABILITY
INTEGRITY
© Yingjiu Li 2005
R. Sandhu
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th
4
Objective
• Usage
– Information is not misused by authorized
parties
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Mitigate TVA
• Threat
– Something bad could happen
• Vulnerability
– Weakness in an information system could be
exploited
• Attack
– Some vulnerabilities are actually exploited by
some adversary, which may result in security
incidents
© Yingjiu Li 2005
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Sources of Cybersecurity Threats
(United States Government Accountability Office GAO-10-606)
Bot-network
operators
Use a network, or bot-net, of compromised, remotely controlled systems to coordinate attacks and to distribute
phishing schemes, spam, and malware attacks. The services of these networks are sometimes made available
on underground markets.
Criminal groups
Seek to attack systems for monetary gain (e.g., identity theft and online fraud) or conduct industrial espionage.
They hire or develop hacker talent.
Hackers
Break into networks for the thrill of the challenge, bragging rights in the hacker community, revenge, stalking
others, and monetary gain, among other reasons
Insiders
Includes disgruntled employees, contractors hired by the organization, as well as employees who accidentally
introduce malware into systems.
Nations
Nations use cyber tools as part of their information-gathering and espionage activities. In addition, several
nations are aggressively working to develop information warfare doctrine, programs, and capabilities.
Phishers
Individuals, or small groups, execute phishing schemes in an attempt to steal identities or information for
monetary gain
Spammers
Individuals or organizations distribute unsolicited e-mail with hidden or false information in order to sell
products, conduct phishing schemes, distribute spyware/malware, or attack organizations (i.e., denial of
service).
Spyware/malware
authors
Individuals or organizations with malicious intent carry out attacks against users by producing and distributing
spyware and malware.
Terrorists
Seek to destroy, incapacitate, or exploit critical infrastructures in order to threaten national security, cause
mass casualties, weaken a nation’s economy, and damage public morale and confidence.
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Attacks
Difficult to detect but
relatively easy to
counteract
Difficult to prevent absolutely but relatively
easy to detect; the goal is to detect them
and to recover from any disruption
Robert Deng/SMU
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© Yingjiu Li 2005
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Hardware and Software Grow
• Moore’s law
– (Hardware) processing power doubles every 18
months
• Gates’ law
– Software grows to use all processing power
• Multics 1970: ~55k lines of code
• Windows 2000: ~55M lines of code
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More Vulnerabilities
• Neumann’s law
– Number of vulnerabilities is proportional to the
square of software size
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High Network Value
• Metcalfe’s law
– Value of a network is proportional to the square
of number of users
– Internet 1970: ~10K users
– Internet 2005: ~1B users
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High Security Risk
• Evan’s Law
– Security risk is the product of the number of
vulnerabilities and the value of network
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Even Worse: Defense is So Hard
Principle of Easiest Penetration
An intruder can exploit any vulnerability to launc an
attack
– An intruder only needs to find one vulnerability
– Defender needs to control all possible vulnerabilities
• Features of cyber attacks
– Action at a distance (difficult to trace & prosecute)
– Propagation of attacking techniques (hacker groups, bulletin
boards; only the 1st needs skill, the rest just use the s/w)
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© Yingjiu Li 2005
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How to Achieve Security Objectives
• Policy
– What to protect
• Mechanism
Security
– How to protect
• Assurance
Assurance
– How well is protection
Mechanism
Policy
© Yingjiu Li 2005
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Can We Hide?
• Security by Obscurity
– A system would be secure if we hide its insides?
• It won’t work well
– Vendor independent standards
– Open source
– Widespread knowledge and expertise
• Kerckhoffs Principle (1883): Only the key
should be kept secret, while the algorithm itself
should be publicly known.
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Can We Instruct?
• Security by legislation
– A system will be secure if we instruct users to behave
in a secure, ethical and lawful manner
– Example: Corporate Acceptable Use Policy
• It is not adequate
– Users’ cooperation is important; however, it should not
be our main focus for achieving security
– Attackers (outsider and insider attackers) will not
follow instructions
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Tradeoffs
• Security is not free
Security
Cost
Functionality/
performance
© Yingjiu Li 2005
Ease of use/
compatibility
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Discussion
• Good security and bad security
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Project
• Project (25%)
– Investigation on a security/privacy related topic (each team
chooses a different topic)
– Project presentation (15%)
• Presentation organization (5%);
• Technical description(5%)
• Q&A (5%)
• Timing: 20~25 min presentation + 5~10 min Q&A
– Final report (10%)
• Breadth (5%)
• Depth (5%)
© Yingjiu Li 2005
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Project – Due Time
• Project outline is due in week 9.
• Project presentation is scheduled in weeks
12 and 13.
• Project report is due in week 14.
© Yingjiu Li 2005
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Topics
1)
2)
3)
4)
Web browser security
SSL security issues and solutions
Privacy leakage and control in online social networks
Authentication and anonymity in location based
services
5) Differential privacy
6) Android permission models and enforcement
7) iOS malware and detection
8) Android malware and detection
9) Timing based attestation
10) Password strength measurements
© Yingjiu Li 2005
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Must do before next class
• Download and install Cryptool
– http://www.cryptool.org/en/ct1-download-en
• CrypTool 1.4.30 - English version
• CrypTool 1.4.31 Beta 05 - English version
• We will use this tool frequently in class
© Yingjiu Li 2005
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