1. also see http://tsquare.gatech.edu/
ECE Spring 2008
also see
Prof. John A. Copeland
fax
Office: Klaus 3362
or call for office visit, or call Kathy Cheek,

2. or http://users.ece.gatech.edu/~copeland/jac/6612/
The class Web site is: or
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 text files, sent to you by and posted on the Web. Answers will be edited into them, and they will be returned by to me.
Since these count for your final grade, treat homework assignments like take-home quizzes. Graded versions will be returned to you by . 2

3. Objectives of Data Security
• Privacy - not readable
• Permanent - not alterable (can't edit, delete)
• Reliable - (changes detectable)
• Signed - (non-reputable)
• Acknowledged - (know it was received)
• Authorization - few have privileges
But the data must be accessible to persons authorized to:
• Read, edit, add, delete
Probably over a network, possibly over the Internet. 3

4. Attacks, Services, and Mechanisms
* Security Attack: Any action that compromises the security of information.
* Security Mechanism: A mechanism that is designed to detect, prevent, or recover from a security attack.
* 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. 4

5. Security Services (P + 5 A's) * Confidentiality (Privacy)
* Authentication (who created or sent the data)
* Integrity (has not been altered) [Alteration (protection)]
* Non-repudiation (the buy-order is final) [Attribution]
* Access control (prevent misuse of resources) [Authorization]
* Availability (permanence, non-erasure)
- Denial of Service Attacks
- Virus that deletes files 5

6. Availability Privacy Alteration, Attribution
Authentication, Authorization 6 6

7. 7

8. Wiring Closet 8

9. Wiring Trough 9

10. 10

11. 11

12. Security Standards Internet - Internet Engineering Task Force (IETF)
De Facto (PGP security system, Kerberos-MIT)
ITU (X.509 Certificates)
- not in book -
National Institute of Standards and Technology (SHA)
IEEE (802.2-Ethernet, Wireless LAN)
Department of Defense, Nat. Computer Security Center
- Tempest (radiation limits)
- Orange Book: Class A1, B3, C1, C2, ...
Export Controls
- High Performance Computers
- Systems with “Hard” Encryption 12

13. IETF - Internet Engineering Task Force RCF - Request for Comments
Wireless Security - IEEE 802 Committee 13

14. Viruses, Worms, and Trojan Horses
Virus - code that copies itself into other programs (usually riding on 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 - many bots controlled by the same organization. 14

15. 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 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 programs, if possible (I use MacOS and Eudora). Avoid Web Mail, integrated mail and browser programs. 15

16. Password Gathering Look under keyboard, telephone etc.
Look in the Rolodex under “X” and “Z”
Call up pretending to from “micro-support,” and ask for it.
“Snoop” a network and watch the plaintext passwords go by.
Tap a phone line - but this requires a very special modem.
Use a “Trojan Horse” program or “key catcher”to record key stokes. 16

17. The 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. 17

18. Clicking on the Wrong Button can Compromise your PC

19. Router-Firewall can drop packets based on source or destination,
Web Server
Browser
Application
Application
Router-Firewall
can drop packets
based on
source or destination,
ip address and/or port
Layer
Layer
(HTTP)
(HTTP)
Port 80
Port 31337
Transport
Transport
Layer
Layer
(TCP,UDP)
(TCP,UDP)
Protocol No.
Protocol No.
Network
Network
Layer (IP)
Layer (IP)
IP Address
Network
Network
IP Address
Layer
Layer
Token Ring
E'net Data
Token Ring
E'net Data
Link Layer
Link Layer
Data-Link Layer
Data Link Layer
Ethernet
Token Ring
E'net Phys.
Token Ring
Phys. Layer
Phys. Layer
Layer
Phys. Layer 19

20. IP Zone-Access Control (xinetd)
/etc/hosts.deny
ALL:ALL
/etc/hosts.allow
in.telnetd:
in.ftpd:
UNIX and Linux computers allow network contact to be limited to individual hosts or subnets ( means any).
Above, telnet connection is available to all on the subnet, and a single off-subnet host, FTP service is available to only to two local hosts, .19 and .102.
The format for each line is “daemon:host-list”.
Use IPtables instead (more detailed, but more complicated) 20

21. PGP (Pretty Good Privacy) -> GPG
From "PGP Freeware for MacOS, User's Guide" Version 6.5, Network Associates, Inc., 21

22. Access Control
Today almost all systems are protected only by a simple password that is typed in, or sent over a network in the clear.Techniques for guessing passwords:
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).
Prevention: Enforce good password selection (e.g.,
“c0p31an6-liKe5=Alvakad05” or “3Bm1ce-c-htr”) 22

23. Kerberos 23