Transcript Trojan Horse - Communications Systems Center

ECE-8843 Fall 2004
http://www.csc.gatech.edu/copeland/jac/8843/
Prof. John A. Copeland
[email protected]
404 894-5177
fax 404 894-0035
Office: GCATT Bldg 579
email or call for office visit, or call Kathy Cheek, 404 894-5696
The class Web site is:
http://www.csc.gatech.edu/copeland/jac/8843/
or http://users.ece.gatech.edu/~copeland/jac/8843/
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 email and posted
on the Web. Answers will be edited into them, and they will be returned
by email to me.
Since these count for your final grade, treat homework assignments like
take-home quizzes. Graded versions will be returned to you by email.
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Objectives of Data Security
(relative to unauthorized persons)
• Privacy - not readable
• Permanent - not alterable (can't edit, delete)
• Reliable - (changes detectable)
• Signed - (non-reputable)
• Acknowledged - (know it was received)
But the data must be accessible to persons authorized to:
• Read, edit, add, delete
Probably over a network, possibly over the Internet.
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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.
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Security Services
* Confidentiality (privacy)
* Authentication (who created or sent the data)
* Integrity (has not been altered)
* Non-repudiation (the order is final)
* Access control (prevent misuse of resources)
* Availability (permanence, non-erasure)
- Denial of Service Attacks
- Virus that deletes files
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Wiring Closet
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Wiring Trough
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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
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
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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.
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Virus Protection
Have a well-known virus protection program, configured to
scan disks and downloads automatically for known viruses.
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.
Avoid the most common operating systems and email
programs, if possible.
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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.
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The Stages of a 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.
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Browser
Web Server
Application
Layer
(HTTP)
Port 80
Transport
Layer
(TCP,UDP)
Segment No.
Network
Layer (IP)
IP Address
130.207.22.5
E'net Data
Link Layer
Ethernet
Phys. Layer
Router-Firewall
can drop packets
based on
source or destination,
ip address and/or port
Network
Layer
Network
Layer
Token Ring
E'net Data
Link Layer Data Link Layer
E'net Phys.
Layer
Token Ring
Phys. Layer
Application
Layer
(HTTP)
Port 31337
Transport
Layer
(TCP,UDP)
Segment No.
Network
Layer (IP)
IP Address
24.88.15.22
Token Ring
Data-Link Layer
Token Ring
Phys. Layer
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IP Zone-Access Control
/etc/hosts.deny
ALL:ALL
/etc/hosts.allow
in.telnetd: 199.77.146 24.88.154.17
in.ftpd: 199.77.146.19 199.77.146.102
UNIX and Linux computers allow network contact to be limited
to individual hosts or subnets (199.77.146 means 199.77.146.any).
Above, telnet connection is available to all on the 199.77.146.0
subnet, and a single off-subnet host, 24.88.154.17 FTP service is
available to only to two local hosts, .19 and .102.
The format for each line is “daemon:host-list”
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IP Zone-Access Control
/etc/hosts.deny
ALL:ALL
/etc/hosts.allow
in.telnetd: 199.77.146 24.88.154.17
in.ftpd: 199.77.146.19 199.77.146.102
UNIX and Linux computers allow network contact to be limited
to individual hosts or subnets (199.77.146 means 199.77.146.any).
Above, telnet connection is available to all on the 199.77.146.0
subnet, and a single off-subnet host, 24.88.154.17 FTP service is
available to only to two local hosts, .19 and .102.
The format for each line is “daemon:host-list”
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PGP (Pretty Good Privacy) -> GPG
From "PGP Freeware for MacOS, User's Guide" Version 6.5, Network Associates, Inc., www.pgp.com
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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 (c0p31an6)
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Kerberos
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