doman’s csci 101 sections

Doman’s CSCI 101 SectionsDoman’s CSCI 101 Sections

http://www.flickr.com/photos/selvin/2762032143/

Computer CrimeMaking and Spreading Viruses

Stealing Corporate Data

Destroying Corporate Data

Stealing Personal Data

Credit card or bank fraud

Identity theft

Denial of Service Attackyou can shut down cnn.com by quickly hitting it

with thousands of bogus requests

Legal Issues

Consequences of computer crimeOr.. 4 bad things that can happen...

Someone gains access to something they are not allowed. - Unauthorised Disclosure

Someone pretends to be someone else to get something they are not allowed. - Deception

Prevent someone from doing their work or prevent the system from doing its work. - Disruption

Something gains control of a system, data or functions for which it is not authorized. - Usurption Copyright: Dave Bremer

Otago Polytechnic, N.Z.©2008, Prentice Hall

Assets – What to secure

Computer Security TriadThree key objectives are at the heart of

computer security

Data and

services

Availability

Confidentiality

Integrity

Threats to Physical SecurityTheftDamage to hardware

Accidental Fire, flood, and earthquake

Destructive Accident Act of terrorism

Unauthorized accessSnooping

Example of Snooping:Wardriving / Warwalking, Warchalking,

Wardriving/warwalking -- driving/walking around with a wireless-enabled notebook looking for unsecured wireless LANs

Warchalking -- using chalk markings to show the presence and vulnerabilities of wireless networks nearbyE.g., a circled "W” -- indicates a

WLAN protected by Wired Equivalent Privacy (WEP) encryption

[Barbara Edicott-Popovsky and Deborah Frincke, CSSE592/492, U. Washington]

[Picture from Wikipedia]

Physical protection measuresRestrict physical access to sensitive

network equipment

Guards, security cameras

Backup copies and archives

Cables and locks (e.g., for notebooks)

Authentication policies

Authentication: Password-Based

Determines if user is authorized to access the system

Determines privileges for the userWhat makes a good password?

Authentication : Biometrics Something the individual is

Static Biometrics: Fingerprint, faceSomething the individual does

Dynamic Biometrics: handwriting, voice recognition, typing rhythm

Threats to Software and DataNatural and man-made disaster protection

Fire, flood, and earthquake protectionAccident and terrorism protection

Threats from authorized personnel

Malware

Protection from disasters

Backup copies and archives

Computer CrimeMost corporate computer crime

is done by employees 58% unauthorized employees 24% authorized employees 13% outside hacker 5% other

Legal Issues

Access ControlDictates what types of access are permitted,

under what circumstances, and by whom.

Protection from authorized users

Role Based Access Control

Role: Cat

Role: Dog

Role: Bird

Malware == Harmful SoftwareGeneral term for any Malicious softWare

Software designed to cause damage Or use up the resources of a target computer.

Some malware is parasiticContained within other software

Some malware is self-replicating, others require some other means to propogate.

Logic BombOne of the oldest types of program threat,

predating viruses and worms, is the logic bomb.

Explodes when certain conditions are metPresence or absence of certain filesParticular day of the weekParticular user running application

Malware

Malware

usually destroys files copies itself ex - a MSWord macro sent via email

Viruses

Virus

Objective: gain control of network and computer Zombie is the infected computer

Attackers access lists of zombie PCs and activate them to help with other bad things or sometimes just with games

Launch attacks that are difficult to trace to bot’s creator

Collection of bots is a botnet

BOTS or ZOMBIES

Malware

Attacker attempts to prevent legitimate users from accessing information or services.

1. select target

2. break into hosts around the network (see botnet)

3. send packets to target from compromised hosts

target

Introduction 1-24

MalwareDenial of Service DoS

Most common: flooding a network with information

Malware

objective: steal information personal information (bank account info, …) passwords e.g. monitor and transmit your keyboard

input AdWare

Spyware

TrapdoorSecret entry pointUseful for programmers debugging

But allows unscrupulous programmers to gain unauthorized access.

Backdoor –

Malware - How they get in

Trojan HorseUseful program that contains hidden code

that when invoked performs some unwanted or harmful function

Replicates itselfThe really bad ones wait for a particular date

Not a virus, but a means to transport viruses

Malware - How they get in

Email is not secure

There are some products and adds-on to make it secure or encrypted.

Email is permanent

Email Security

Email

Email is not secure

Anti-Virus Software looks for known viruses and common virus formats

Anti-Spyware Software

Keep operating system and protection programs updated with latest fixes.

If you notice anything odd, like your computer seems to slow down or crash for no apparent reason,

Run your anti-virus and anti-spyware programs!

Protection from malware

University and Industry security research

Honeypot System or network designed to attract

malwareWhen discovered, the malware is

researched An antidote is written

Protection from malware

WormsObjective is to destroy the network (not your

PC)

Use network connections to spread from system to system, replicating itself

Email virus has elements of being a worm (self replicating)But normally requires some intervention to

run, so classed as a virus rather than worm33

Malware

Network Security ThreatsQ: What can a “bad guy” do?A: A lot!

eavesdrop: intercept messagesactively insert messages into connectionimpersonation: can fake (spoof) source

address in packet (or any field in packet)hijacking: “take over” ongoing connection

by removing sender or receiver, inserting himself in place

denial of service: prevent service from being used by others (e.g., by overloading resources)

Starting to think about network security

Protection for Network SecurityWe need to ensure:1.Messages get to destination without being altered 2.Only the persons we want will read our messages3.We need to ensure that source of message is who/what you think it is4.Sender and receiver are not being impersonated

Message Digests

Encryption

Digital Signatures

Certification Authorities

We need to ensure messages get to destination without being altered

Message Digests

Protection for Network Security

42

Message IntegrityAllows communicating parties to verify

that received messages are authentic.Content of message has not been altered

Achieved with1.Message digests2.Digital signatures3.Certification Authorizations

43

Message DigestsFunction that uses the

actual message data to come up with a short code or ID. This is called a : “message signature”

Attach that to the message

MACMessage

(Message Authentication Code)

44

Compare Message Authentication Code (MAC) to ensure message integrity

mes

sage

Message Digest Function

MAC

mes

sage

mes

sage

compare

Message Digest Function

MAC MAC

MAC

MAC

We need to ensure only the persons we want will read our messages

Encryption

Protection for Network Security

46

Simple encryption schemesubstitution cipher: substituting one thing for another

monoalphabetic cipher: substitute one letter for another

plaintext: abcdefghijklmnopqrstuvwxyz

ciphertext: mnbvcxzasdfghjklpoiuytrewq

Plaintext: bob. i love you. aliceciphertext: nkn. s gktc wky. mgsbc

E.g.:

Key: the mapping from the set of 26 letters to the set of 26 letters

Encryptionsymmetric key encryption1 encryption key

public key encryption2 encryption keys

49

Symmetric (Shared) key cryptography

symmetric key crypto: Bob and Alice share same (symmetric) key: K

e.g., key is knowing substitution pattern in mono alphabetic substitution cipher

Q: how do Bob and Alice agree on key value? Symmetric (shared) key exchange video

ciphertext

K S

encryptionalgorithm

decryption algorithm

S

K S

K (m)S

Uses key to decode message

Uses key to encode message

50

Public Key Cryptographysymmetric key cryptorequires sender,

receiver know shared secret key

Q: how to agree on key in first place (particularly if never “met”)?

public key cryptography sender, receiver do not

share secret key public encryption key

known to all private decryption key

known only to receiver

51

Public key cryptography

ciphertextencryptionalgorithm

decryption algorithm

Bob’s public key

K B+

Bob’s privatekey

K B-

Uses PUBLIC key to encode message

Can not decode message!

Uses PRIVATE key to decode message

We need to ensure that source of message is who/what you think it is

Digital Signatures

Protection for Network Security

Transfer $1Mfrom Bill to Trudy

Transfer $1M fromBill to Trudy

Playback attack – Who really sent this?

54

Digital Signatures

Cryptographic technique analogous to hand-written signatures.

Sender (Bob) digitally signs document, establishing he is document owner/creator.

Simple digital signature for message m:Bob signs m by encrypting with his

PRIVATE key, creating “signed” message.

We need to ensure that the sender or receiver is not being impersonated

Certification Authority

Protection for Network Security

56

Public-key certificationMotivation: Trudy plays pizza prank on Bob

Trudy creates e-mail order: Dear Pizza Store, Please deliver to me four pepperoni pizzas. Thank you, Bob

Trudy signs order with her private keyTrudy sends order to Pizza StoreTrudy sends to Pizza Store her public key, but

says it’s Bob’s public key.Pizza Store verifies signature; then delivers four

pizzas to Bob.Bob doesn’t even like Pepperoni

57

Certification AuthoritiesCertification authority (CA): binds public key to

particular entity, Bob.Bob(person, router) registers its public key

with CA.Bob provides “proof of identity” to CA. CA creates certificate binding Bob to its public key.certificate containing Bob’s public key digitally signed

by CA – CA says “this is Bob’s public key”Bob’s public

key

Bob’s identifying

information

certificate for Bob’s

public key, signed by

CA

58

Certification AuthoritiesWhen Alice wants Bob’s public key:

gets Bob’s certificate (Bob or elsewhere).apply CA’s public key to Bob’s certificate,

get Bob’s public key

Bob’s public

key

Firewalls

FirewallsPrevent access to the network by

unauthorized usersComposed of software and/or hardware

61

SSL: Secure Sockets LayerWidely deployed security protocol using

Encryption (especially credit-card numbers) Server authentication

Provides Confidentiality Integrity Authentication

Identified by the prefix https://

62

Virtual Private Networks (VPNs)Institutions often want private networks

for security. Costly!

With a VPN, institution’s inter-office traffic is sent over public Internet instead. But inter-office traffic is encrypted before

entering public Internet

Client must sign in to VPN to access the network

Protection via Security PolicyHardware security

Lock desktopsLaptops, phones,

etcLog off!!

Password SecurityPassword strengthChanging password

Encryption

Resource SecurityFilesMark document as

finalPassword protectCopyright