1

“The public streets and highways of the internet have become like neighborhoods where it is no longer safe to venture. Hackers, scammers, virus builders and other Web predators are looming in the shadows.”

-- Paul Tinnirello CIO in an insurance financial industry

“The Gated Community”, e-Week, 13 Oct 2003

Computer Crimes

An information session for participants in the 57-201 Introduction to Forensic Science course

Akshai AggarwalSchool of Computer Science

3

Flow of the session Historical perspective 4-14 Threats and Attacks

Threats 18-21 Types of Attacks 23-30

Technology of defence 32-50 Laws and group Efforts in Canada 51 A couple of general ideas, in conclusion

Note: Terminology may be explained, as the need arises.

4

Historical Perspective: Terminology 1960s and 1970s:Hacker: a positive term

A Hacker: An expert, knowledgeable about programming and operating systems

1970s onwards:Hacker: a term, which progressively became more

negative.

A Hacker: Someone using computers without authorization..Hacker: Someone committing crimes by using computers

5

Types of Non-authorized Users Hacker: people who access a computer

resource, without authorization Crackers: a hacker who uses his or her skills to

commit unlawful acts, or to deliberately create mischief

Script Kiddies: a hacker who downloads the scripts and uses them to commit unlawful acts, or to deliberately create mischief, without fully understanding the scripts.

VandalsReference:http://www.e2chameleon.btinternet.co.uk/

hacking.htm

6

Terminology of Hacking Eavesdropping or Snooping (also called

passive wire-tapping)

Active wire-tapping or man-in-the middle attack

Dumpster Diving: colloquial for looking through all the easily available material before an actual intrusion into a system

7

The Global Net: A Virtual Intelligent Global System2 Sept 1969 LEN KLEINROCK’S Lab at UC,LA

1971 15 Nodes 23 Hosts

1973 BOB METCALFE’S thesis on ETHERNET at Harvard

1974 TCP: CERF & BOB KAHN’S paper 1983 DoD Official Protocol. 1989 Hypertext & WWW at CERN by Berner Lee

Then came the BROWSER’S MOSAIC NCSA and the WWW

8

Security Technologies:A little history of an ancient art: The first printed book on cryptologyJohannes Trithemius, an abbot in Spanheim :

One of the founders of cryptology

The first printed book of cryptology: titled “Polygraphiae Libri Sex “ in German language in 1518 by Johannes Trithemius,published after the death of the writer.

(The title means -Six Books of Polygraphy)

9

A little history (continued)

Earlier in 1499 he had written a 3-book“Steganographia”, (meaning covered

writing): which was circulated privately was published in 1606.

The first two books: about cryptology. But the third book could not be

understood, without understanding the encoding that he had used.

10

A little history (continued): A challenge for a cryptanalyst

In the third book, which was considered to be incomplete, Trithemius explained why he had made it hard to understand:

“This I did that to men of learning and men deeply engaged in magic, it might, by the Grace of God, be in some degree intelligible, while on the other hand, to the thick skinned turnip-eaters it might for all time remain a hidden secret, and be to their dull intellects a sealed book forever.”

11

“Ban, what you don’t understand.”

The third book: banned in 1609, ostensibly because it explained how to employ spirits for sending secret messages.

The challenge - of deciphering the book: met by three persons in 500 years

1676:Wolfgang Heidel, the archbishop of Mainz, Germany, claimed to have deciphered the third book of Trithemius.

But his discovery was stated in a secret code of his own. So nobody knew whether Heidel had understood the book.

12

A little history: Deciphering the third book of Trithemius 1996:Thomas Ernst, Prof of German at La Roche

College, Pittsburgh published a 200-page German-language report in a small Dutch journal, Daphnis.

WIDELY KNOWN SOLUTION: spring 1998: Jim Reeds of AT & T labs solved the riddle of understanding the third book independently.

He did not know of the earlier work of Ernst.Trithemius work: basically simple: Ernst took two

weeks and Reeds took two days to understand it.Both Ernst and Reeds, separately, deciphered

Heidel’s work and found that Heidel had been able to decipher Trithemius’ third book.

13

The first attack The Internet Worm (Nov 1988)

Morris, a graduate student at CMU released a program on the internet:

utilized a security hole in the mail receipt software

automatically replicated itself locally and to remote machines

affected a wide class of machines and effectively shut down internet for 1-2 days.

Cost estimate to fix: $5 million

14

The first conviction Mitnick and Shimomura (Christmas

1994) Used SYN flooding and TCP Hijacking to

connect to Shimomura’s home machine. Stole copies of 1000’s of files including

specialized computer security software; modified log files to remove signs of entry.

Shimomura found out about the entry and informed FBI.

15

“….there will be more security breaches”,

says Schneier As more of our infrastructure moves online,

as more things, that someone might want to access or steal, move online …….

As our networking systems become more complex …..

As our computers get more powerful and more useful…..

16

Common attacks on banks through InternetLosses due to attacks:"The major banks don't want to

divulge the amount of losses. But just to give one example, a major Australian bank has put several million dollars in reserve since August 2003 to cover damages due to Internet frauds.“– Dave Jevans, eWeek, Dec 2003

17

Causes of Security Problems on Internet

Internet Technology: was developed based on trust

Security features: added, as different types of attacks are mounted.

Users: bother about ease of use and not about security

18

Security Threats RFC 1244 identifies three distinct types

of security threats associated with network connectivity: Unauthorized access

A break-in by an unauthorized person. Break-ins may be an embarrassment that

undermine the confidence that others have in the organization.

Moreover unauthorized access one of the other threats:-- disclosure of information or

--denial of service.

19

Classification of Security Threats Reference: RFC 1244

Disclosure of information disclosure of valuable or sensitive information to

people, who should not have access to the information. Denial of service or Degradation of service

Any problem that makes it difficult or impossible for the system to continue to perform productive work.

Do not connect to Internet: a system with highly classified information, or, if the risk of liability in case of disclosure is

great.

20

Brent Chapman’s Three Categories of Security Threats

Brent Chapman’s Classification: Confidentiality

Of data Of existence of data Of resources, their operating systems,

their configuration Of resources used, in case the resources

are taken on rent from a service provider

21

Information Security Threats Chapman’s Classification

(contd.)

availability: A DoS attack may disrupt availability of a service, or availability of data

integrity Of data Of origin: Once someone has gained unauthorized accessto a system, the integrity of the information onthat system is in doubt.

22

Loss Breakdown

Physical security

problems20%

Dishonest employees

10%

Human error55%

Viruses4%

Outsider attacks

2%

Disgruntled employees

9%

Reference: Jim Alves-Foss , Center for Secure and Dependable Systems, Univ of

Idaho, http://www.cs.uidaho.edu/~jimaf/cs442/crime-talk.ppt

23

Types of Attacks Attacks on computer systems using the

computers Web-site defacement or Revealing the data to unauthorized persons/theft of

sensitive information/ stealing information having Intellectual Property Rights

like stealing credit card numbers bank frauds or

Damage to data

through Hacking or Virus/Worms

24

Types of Attacks continued

Hoax Letters: Examples Malicious code (viruses and trojan horses) Urban myths Scam letters to entrap the receiver

Internet gambling Internet Pornography/ stalking Link Flooding Packet Intercepting, Password

Sniffing

25

Types of Attacks

propagate false routing entries (“black holes” and “sink holes”, www.citibank.com, www.mybank.az)

domain name hijacking Phishing attacks: use e-mails that often

appear to come from a legitimate e-mail address and include links to spoofed Web addresses. The receiver responds to the link, which takes the receiver to a site, other than what the receiver thinks he is going to. (announced by MS on 16 Dec 2003, as a problem with Internet Explorer).

26

Anti-Phishing.org A Web site www.antiphishing.org,, for reporting

incidents, set up by a group of global banks and technology companies, led by Secure-messaging firm Tumbleweed Communications Corp

Fast Response required: The Web sites designed for collecting personal information in phishing attacks are often alive for a day only.

Example: Dec 2003:The e-mail appeared to come from the U.K. bank NatWest.

Anti-Phishing.org tracked the IP address to a home computer in San Francisco.

But a clear case of spoofing—the mail was relayed from a hijacked computer (called a zombie)

27

An Example: time-to-market for Internet Security

products

16 December, 2003: Discovery of the problem of Phishing

5 January 2004: Announcement of development of a new Anti-phishing service by Netcraft, of Bath, England.

Netcraft says that the service is mainly for banks and other financial organizations

28

Other Computer Crimes Spoofing or Masquerading of a host or a

service-provider (Distinguish it from Delegation)

Repudiation of origin or of creation of some file

Denial of receipt Usurpation: unauthorized control Data Diddling (To enter false data

intentionally)

29

‘To be an effective Information Warrior, individuals need superior computer skills, as well as an in-depth understanding of information technology architectures,… protocols and processes.’

--- Michael Erbschloeauthor of “Information Warfare: How to Survive Cyber Attacks”

30

General Strategies for security

encrypting sensitive data reduce size of target: disable unneeded services limit access of attacker to target

systems hardening the OS and applications

31

“It is insufficient to protect ourselves with laws; we need to protect ourselves with mathematics.”

---Bruce Schneier

in ‘Applied Cryptography’

32

CRYPTOGRAPHY

Cryptography (from two words in Greek): means secret writing.

Cryptoanalysis: breaking of a cryptographic code

CRYPTOGRAPHY: process data into unintelligible form, reversibly/irreversibly without data loss usually one-to-one in size /compression

33

CryptographyServices, provided by cryptographic tools:

Encoding information into a form which makes the information unintelligible to an unauthorized person

integrity checking: no tampering authentication: not an impostor

Encryption or Enciphering

Encryption AlgorithmPlaintext

Key

Ciphertext

34

Encryption

Two types of Encryption Algorithms Reversible Irreversible

Two types of Keys Symmetric Assymetric

35

Reversible Encryption

Reversible ENCRYPTION:

cleartext ENCRYPTION DEVICE encryption key

cleartext

can be used only when the same type of encryption software/equipment is available at both the ends

ciphertext

Decryption Device

Decryption key

36

Decryption

Decryption or Deciphering

DecryptionAlgorithm

Ciphertext

Plaintext

Key

37

Cryptographic Hash Functions (H) H : A transformation: One way m = variable size input h = hash value : a fixed size string, also known as message digest or

fingerprint or compression function.

H(m)m h

38

Message Digest (recapitulation)

VariableLengthMessage

HashingAlgorithm

Fixed LengthDigest

39

Secret Key/ Symmetric Cryptography

Simpler and faster (than ?) and, of course, secure For Integrity check, a fixed-length checksum for the

message may have to be used; CRC* not sufficient*Cyclic Redundancy Check

40

Symmetric Key Encryption

Also called Private/Secret key Encryption

Sender-endMessageby sender

Messageat receiver

Pr-key

Pr-key

EncryptedMessage

EncryptedMessage

Internet

Receiver-end

41

public-key cryptography (continued)

42

Asymmetric Key Encryption

Also called Public key Encryption

Message

Message

B’s public

B’s private

EncryptedMessage

EncryptedMessage

Internet

A

B

key

key

43

public-key cryptography (continued) Data transmission: private key(d), public

key (e)

44

public-key cryptography (continued)Applications and Advantages: Storage: for safety: use public key of trusted

person Secret vs. Public Key system: secret key system: needs secret key for every pair

of persons, that wish to communicate n users n(n-1)/2 keys public key system: needs two keys for every

person, who wants to communicate. n users 2n keys

45

Digital certificate for getting Public Key reliably A digital certificate from a trusted party

may contain: The name of a person His e-mail address His public key

The recipient of the encrypted certificate uses the public key of the Certification Authority to decode the certificate.

Examples of CAs: www.verisign.com or www.thawte.com (Verisign’s liability limited to $100 only!)

Standard for certificate: X.509

46

Digital signatures

Digital Signatures: A is to sign a Msg and send it to B

Msg

Msg

Msg +EncodedDigest

DigestAlgorithm

Msg +EncodedDigest

DigestAlgorithm

Decode digest using Public key of A

Encoding using Private key of A

Digest

Digest

Compare

BA

47

Laws and Group Efforts in Canada No separate cyberspace law in Canada But the Canadian Criminal Code and the

Canadian Human Rights Act apply in cyberspace.

The Internet Protection Portal, established by the Canadian Association of Internet Providers (CAIP): an on-line window to resources for a user to safeguard the Internet experience.

Media Awareness Network (MNet): supports media education in Canadian homes, schools and communities.

48

Birthday paradox

A result from probability theory: Consider an element that has an equal probability of assuming any one of the N values. The probability of a collision is more than 50% after choosing 1.2√N values.

FunctionRandom input

One of k equally likely values

The same output can be expected after 1.2k1/2 inputs. Thus in a group of 23, two or more persons are likely to share the same birthday. (Put k = 365) Birthday attacks are used to find collisions of Hash functions

49

Example of a Birthday AttackAssume A 64 bit key The first statement in a message is always the

same.A hacker listens to and stores all encrypted messages. When the FIRST encrypted sentence turns out to

be the same, he replaces the rest of the new message by the old message, that he has in his memory.

By Birthday Paradox, this is likely to happen after 232 transactions.

50

Cryptography vs. Steganography

Cryptography : uses techniques like transpositions and substitution to make a message unintelligible

Steganography : hides the existence of the method.

Cryptography provides privacy. Steganography provides secrecy.

51

Hiding a message in a picture Described by Wyner in ‘Byte’

Kodak photo CD resolution of 2048x3072 pixels. Each pixel: 24-bit RGB color information. Modify the last bit (out of 8 bits) for each color. Amount of data that can be hidden in a single

picture:2048 * 3072*3 = 2.359296 Mb = about 300,000B 10^6

If four bits of intensity for each of the three colors RGB are altered 1.5 text characters hidden in each pixel of the photo.

A 640x480 pixel image can store over 400,000 characters, equal to a whole book.

52

Steganography: Hiding Messages: Example of a Laser printerAnother example: Laser printers can

adjust spacing of lines and characters by less than 1/300th of an inch.

To hide a 0, leave a standard space.To hide a 1, leave 1/300th of an inch more

than usual. Varying the spacing over an entire document canhide a short binary message that is undetectableby the human eye. The hidden message will be carried by every

photocopy of the document also.

53

To Intrusion Detection Analysts

“Folks! You are the trackers of the 21st

century. The signs are there, plain as day. It

is up to you to find them and give the interpretation.”

Stephen Northcutt et.al.

54

References:

The Trithemius riddle :1. Thomas (Penn) Leary,” Cryptology in the 16th and 17th Centuries”, Cryptologia, July 1996, available at http://home.att.net/~tleary/cryptolo.htm

2. http://www.post-gazette.com/healthscience/19980629bspirit1.asp

3. Gina Kolata, ”A Mystery Unraveled, Twice”, The New York Times, April 14, 1998, pp. F1, F6, available at http://cryptome.unicast.org/cryptome022401/tri-crack.htm

Hoax letters: http://hoaxbusters.ciac.org/