ECE-6612 Spring 2014
http://www.csc.gatech.edu/copeland/jac/6612/
also see http://tsquare.gatech.edu/
Prof. John A. Copeland
john.copeland@ece.gatech.edu
404-894-5177
cell 404-786-5804
Office: Klaus 3362
email or call for office visit
1-7-15
The class Web site is:
http://www.csc.gatech.edu/copeland/jac/6612/
or http://users.ece.gatech.edu/copeland/jac/6612/
On this site you will find:
• Class calendar (test dates, etc.)
• Reading assignments (about 20 pages, read before class)
• Lecture Notes (ppt files, to print)
• Homework assignments (and answers), a Q&A folder
Homework assignments will be posted on tsquare.gatech.edu (link).
Answers will either be edited into the Web page, or uploaded to T-square
as a text or MS Word file.
Since these count for your final grade, treat homework assignments like
take-home quizzes. Graded versions will be not be returned to you, so
you should check your answers against the answers provided on the class
Web page. In some cases a grade of 100% may only indicate the
homework was received on time and complete.
2
Attacks, Services, and Mechanisms
* Security Attack: Any action that compromises the security
of information (e.g., stealing information).
* Security Mechanism: A mechanism that is designed to
detect, prevent, or recover from a security attack. (e.g.,
encryption)
•Security Service: A service that enhances the security of
data processing systems and information transfers. A
security service makes use of one or more security
mechanisms (SSL for Web browsers and servers).
• Service - prevents Attacks - by using Mechanisms
3
Security Services
(PI and 3 A's)
* Privacy (Confidentiality)
* Integrity has not been altered or deleted)
* Availability (accessibility - permanence, non-erasure)
- Denial of Service Attacks
- Virus that deletes files
* Authentication (who created or sent the data - also user login)
- Non-repudiation (the buy-order is final)
[attribution]
* Authorization (access control, prevent misuse of resources)
Ref: ISO X.800 and IETF RFC 2424
4
Availability
Integrity, Authentication
Privacy
Authentication, Authorization
5
Computer Emergency Response Team - see www.us-cert.gov
also see www.sans.org
6
Not included above: Theft of Services. Example, a
botnet uses your computer to send spam email, or
participate in a distributed denial-of-service attack
(DDoS)
7
Wiring Closet
Rule 1:
Without
physical
security (to
critical areas),
there is no
security.
8
Wiring Trough
9
10
Authentication
Authorization
Logging
11
Security Standards
Internet - Internet Engineering Task Force (IETF)
De Facto (PGP email security system, Kerberos-MIT)
ITU (X.509 Certificates)
- not in book National Institute of Standards and Technology (SHA)
IEEE (802.3-Ethernet, 802.11 - Wireless LAN)
Department of Defense, Nat. Computer Security Center
- Tempest (radiation limits)
- Orange Book: Class A1, B3, C1, C2, ...
- Health, Student, Bank, ... Data protection rules.
Export Controls ( U.S. Dept. of Commerce)
- High Performance Computers
- Systems with “Hard” Encryption
12
IETF - Internet
Engineering Task Force
RCF - Request for
Comments
Wireless
Security IEEE 802
Committee
See: www.ietf.org
13
Viruses, Worms, and Trojan Horses
Virus - code that copies itself into other programs (usually riding on
email messages or attached documents (e.g., macro viruses).
Payload - harmful things it does, after it has had time to spread.
Worm - a program that replicates itself across the network
(Sapphire: single UDP packet, MSblast: TCP opened a back-door)
Trojan Horse - instructions in an otherwise good program that cause
bad things to happen (sending your data or password to an attacker
over the net).
Logic Bomb - malicious code that activates on an event (e.g., date).
Trap Door (or Back Door) - undocumented entry point written into
code for debugging that can allow unwanted users.
Bot (robot) - a compromised host that is controlled remotely.
Bot Net (botnet) - many bots controlled by the same organization.
14
Virus Protection
Have a well-known virus protection program, configured to
scan disks and downloads automatically for known viruses.
Monthly (if not weekly) database updates are necessary.
Do not execute programs (or "macro's") from unknown
sources (e.g., PS, JPEG, & HTTP files, HyperCard files, MS
Office documents, Java, ...), if you can help it. Lately,
downloaded image files can compromise your PC.
Avoid the most common operating systems and browser
programs, if possible (I use MacOS and Chrome). If you
use Web Mail (Web-based mail-server programs like
Zimbra) then turn off "automatically download objects
from Web,” and use safe (e.g., GT) servers.
15
Password Gathering
(Physical Security)
Look under keyboard, telephone etc.
Look in the Rolodex under “X” and “Z”
Call up pretending to be from “micro-support,” and ask for it.
“Snoop” a network and watch for plaintext passwords that go by.
Tap a phone line - but this requires a very special modem.
Use a “Trojan Horse” or “Bot” program, with a “key catcher”to record key
stokes.
SSH password guessing.
Social Engineering - phone or email and pretend to be “PC support.”
16
The 5 Stages of a Classical Network Intrusion
1. Scan the network to:
• locate which IP addresses are in use,
• what operating system is in use,
• what TCP or UDP ports are “open” (being listened to
by Servers).
2. Run “Exploit” scripts against open ports
3. Get access to Shell program which is “suid” (has “root”
privileges).
4. Download from Hacker Web site special versions of systems
files that will let Cracker have free access in the future without his
cpu time or disk storage space being noticed by auditing
programs.
5. Use IRC (Internet Relay Chat) to invite friends to the feast, or
“Hoover and Burn” (download information and wipe or crash), or
join the host to a botnet.
17
Clicking on the Wrong Button can Compromise your PC
<- Example
18
Today: Phishing Email, Web Images, …
Today most computer compromises come from email or browsing
a compromised Web site.
It’s no longer necessary to “click here” on an email, if your email
viewer is configured to automatically download objects from Web
sites.
Malware “droppers” can be imbedded in images (even the
favicons), audio files, or almost any Web object.
Bot nets spread there automatically. Once infected, the malware
can download additional capabilities. Keyboard catchers are
common to collect passwords.
19
Many organizations have access to everything on your cell phone:
memory contents, location, camera sight and sound.
20
Web Server
Fire Wall
Application
Layer
(HTTP)
Port 80
Transport
Layer
(TCP,UDP)
Router-Firewall
can drop packets
based on
source or destination,
ip address and/or port
Protocol No.
Network
Layer (IP)
IP Address
130.207.22.5
E'net Data
Link Layer
Ethernet
Phys. Layer
Network
Layer
Network
Layer
Token Ring
E'net Data
Link Layer Data Link Layer
E'net Phys.
Layer
Token Ring
Phys. Layer
Browser
Application
Layer
(HTTP)
Port 31337
Transport
Layer
(TCP,UDP)
Protocol No.
Network
Layer (IP)
IP Address
24.88.15.22
Token Ring
Data-Link Layer
Token Ring
Phys. Layer
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Uncomplicated Fire Wall (UFW)
Configures Linux iptables firewall
#!/bin/bash
# ufw flush - must delete rules manually; ufw delete 1
"y"
ufw allow proto tcp from 130.207.16.17 to any port 22
ufw allow proto tcp from 143.215.52.0/25
ufw allow proto tcp from 130.207.25.13 to any port 22
ufw allow proto tcp from 68.88.0.0/16 to any port 22
ufw allow proto tcp from 30.55.0.0/16 to any port 22
ufw deny from 0.0.0.0/0 # deny connections not above
ufw status numbered
# examine rules before enabling
echo
you must
type: but
'ufw
” (easy setup - UFW)
2005 -"Now
Linux iptables
(more detailed,
moreenable’
complicated)
2010 - Windows - use OS host-based firewall utility
Mac - buy “Little Snitch” - www.obdev.at/products/littlesnitch/index.html
22
PGP (Pretty Good Privacy) -> GPG
From "PGP Freeware for MacOS, User's Guide" Version 6.5, Network Associates, Inc., www.pgp.com
23
Access Control
Yesterday almost all systems were protected only by a simple
password that is typed in, or sent over a network in the clear.
Techniques for guessing passwords (as seen on TV):
1. Try default passwords.
2. Try all short words, 1 to 3 characters long.
3. Try all the words in an electronic dictionary(60,000).
4. Collect information about the user’s hobbies, family names,
birthday, etc.
5. Try user’s phone number, social security number, street
address, etc.
6. Try all license plate numbers (123XYZ).
These can be automated and run off-line if the password
hash file is obtained.
Prevention: Enforce good password selection (e.g.,
“c0p31an6-liKe5=Alvakad05” or “3Bm1ce-c-htr”)
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Bot Nets
Today many system compromises start by the hacker getting a
user to load and run a program* that installs a network backdoor
and automated software, which in turn loads additional software,
making the computer into a "bot" (robot).
These bots join a peer-to-peer network, and can infect other
computers directly over the network. They also can be
commanded by the "bot master" to setup phony Web sites and
send HTML emails that download exploit software into other
computers.
We'll discuss different attacks that are used to steal password and
other identity information, and to misdirect Web browsers to
phony Web sites.
* or render an image or audio file.
25
Network Security Defensive Technology
Secret Key and Public/Private Key Cryptography
Cryptographic Hashes and Message Digests
Authentication Systems (Kerberos)
Digital signatures and certificates.
Kerberos and X.509v3 digital certificates.
Security standards - SSL/TLS and SET.
PGP and S/MIME for electronic mail security.
Firewalls. Intrusion Detection.
Current Network Security Publications and Web Sites
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