COS 338 Day 18. DAY 18 Agenda Second capstone progress report over due Lab 5 graded 1 A, 2 B’s, 2 F’s and 1 non-submits Assignment 5 Graded 2 A’s, 2 B’s

COS 338

Day 18

DAY 18 Agenda

Second capstone progress report over due Lab 5 graded

1 A, 2 B’s, 2 F’s and 1 non-submits

Assignment 5 Graded 2 A’s, 2 B’s and 2 non-submits

Lab 6 Due Assignment 6 Posted

Due November 17

Monday November 14 is Road Trip To UM http://www.umcs.maine.edu/~markov/seminarsf05.html http://www.papert.org/ Meet by Physical Plant at 10:15, Van leaves promptly at 10:30 AM

Today we will begin finish discussing Security Along with Security for windows XP (chap 9a)

Security Management

Figure 9-10: Digital Certificate Authentication

Digital Certificate

User gets secret private key and non-secret public key

Digital certificates give the name of a true party and his or her public key


Testing a Digital Signature

Applicant performs a calculation with his or her private key

Verifier tests calculation using the public key found in the true party’s digital certificate

If the test succeeds, the applicant must be the true party

Figure 9-11: Testing a Digital Signature

Digital Certificate Digital Signature

Authentication

Name of True PartyPublic Key of

True Party

Digital SignatureCreated with Private Key of

Applicant.Added to each

Message.


Strong Authentication The strongest method today

Expensive and Time-Consuming to Implement Software must be added to clients and servers, and

each computer must be configured

Expensive because there are so many clients in a firm


Client Weaknesses Sometimes, only server gets digital certificate

Client uses passwords or something else

Figure 9-11: Testing a Digital Signature

Verifier must test the digital signature with the public key of the true party.

If the test succeeds, the applicant must have the true party’s private key.

Only the true party should know this private key; so the applicant must be the true party.

Figure 9-12: Biometric Authentication

Biometric Authentication Based on bodily measurements

Promises to dramatically simplify authentication


Fingerprint Scanning Simple and inexpensive

Substantial error rate (misidentification)

Often can be fooled fairly easily by impostors

Dominates biometrics today


Iris Scanners Scan the iris (colored part

of the eye)

Irises are complex, so strong authentication

Expensive

(Do NOT shine light in your eyes; scanner is a camera.)


Face Recognition

Camera allows analysis of facial structure

Can be done surreptitiously—without the knowledge or consent of person being scanned

Very high error rate and easy to fool


Error Rates and Deception

Error and deception rates are higher than vendors claim

Usefulness of biometrics is uncertain

Firewalls, IDSs,and IPSs

Figure 9-13: Firewall Operation

Corporate Network The Internet

Log File

Arriving Packets

Permit (Pass)Legitimate

Packet

Deny(Drop)AttackPacket

Application Message

Application Message

ICMP MessageIP-H

IP-H

IP-H TCP-H

UDP-H

StaticPacketFilter

Firewall

Figure 9-14: Access Control List (ACL) for a Packet Filter Firewall

1. If destination IP address = 60.47.3.9 AND TCP destination port = 80 OR 443, PASS [connection to a public webserver]

2. If ICMP Type = 0, PASS [allow incoming echo reply messages]

3. If TCP destination port = 49153 to 65535, PASS [allow incoming packets to ephemeral TCP port

numbers]

Figure 9-14: Access Control List (ACL) for a Packet Filter Firewall

4. If UDP destination port = 49153 to 65535, PASS [allow incoming packets to ephemeral UDP port

numbers]

5. DENY ALL [deny all other packets]

Figure 9-15: Stateful Firewall Default Operation

Internal HostExternal

Host

Internally initiatedcommunication

is allowed.

Externallyinitiated

communicationis stopped.

X

Figure 9-16: Application Firewalls

Application Firewalls

Examine application layer messages in packets

Packet filter firewalls and stateful firewalls do not look at application messages at all

This makes them vulnerable to certain attacks


Application Fidelity

Requiring the application using a well-known port to be the application that is supposed to use that port

For instance, if an application uses Port 80, application firewall requires it to be HTTP, not a peer-to-peer file transfer program or something else

This is called enforcing application fidelity


Limited Content Filtering

Allow FTP Get commands but stop FTP Put commands

Do not allow HTTP connections to black-listed (banned) websites

E-mail application server may delete all attachments


Antivirus Scanning

Few application firewalls do antivirus filtering

Packets also must be passed through separate antivirus filtering programs

Figure 9-17: Defense in Depth with Firewalls

ClientwithHost

FirewallSoftware

Internet

ApplicationFirewalle-mail,HTTP,

etc.

MainFirewall:Stateful

InspectionFirewall

ScreeningBorder

Router withPacket Filter

FirewallSoftware Site

Figure 9-18: Firewalls

Log File

HardenedServer

IDS

HardenedClient PC

Network ManagementConsole

InternalCorporateNetwork

InternetFirewall

Allowed LegitimatePacket

LegitimateHost

LegitimatePacket

Attacker

Figure 9-18: Firewall

Log File

HardenedServer

IDS

HardenedClient PC



InternetFirewall

LegitimateHost

AttackerAttackPacket

DeniedAttackPacket

Figure 9-18: Intrusion Detection System (IDS)

Log File

IDS

HardenedClient

PC



IDS

LegitimateHost

AttackerAlarmAbout

SuspiciousPacket

Suspicious Packet

Hardened Server

SuspiciousPacket

Figure 9-18: Intrusion Prevention Systems (IPSs)

Firewalls stop simple attacks

IDSs can identify complex attacks involving multiple packets But many false positives (false alarms)

Intrusion prevention systems (IPSs) Like IDSs, can identify complex attacks

Unlike IDSs, also stop these attacks

Only allowed to stop clearer complex attacks

Figure 9-19: Cryptographic System (SSL/TLS)

Applicant(Customer Client)without Digital Certificate

Verifier(Merchant Webserver)with Digital Certificate

Provides Protection at Transport Layer

Protects all Application TrafficThat is SSL/TLS-Aware (Mostly HTTP)




1.Negotiation of Security Options (Brief)

2.Merchant Authenticates Self to Customer

Uses a Digital CertificateCustomer Authentication Is Optional and Uncommon




3.Client Generates Random Session Key

Client Sends to Server Encrypted by Merchant’s Public Key

4.Ongoing Communication with Confidentiality

and Merchant Digital Signatures


Perspective

Initial Hand-Shaking Phases are Very Brief (Milliseconds)

The Last Phase (Ongoing Communication) Is Almost All Total Communication

Encryption for Confidentiality

Figure 9-20: Symmetric Key Encryption and Public Key Encryption

Symmetric Key Encryption for Confidentiality

Message“Hello”

EncryptionMethod &

Key

SymmetricKey

Party A

Party B

InterceptorNetwork

Encrypted Message

Encryption uses anon-secret encryption method and

a secret key



Encrypted Message

SymmetricKey

Party A

Party B

InterceptorNetwork

Interceptor cannot readencrypted messages

Encrypted Message



Message“Hello”

EncryptionMethod &

Key

Encrypted Message Message“Hello”

DecryptionMethod &

Key

SymmetricKey

SameSymmetric

Key

Party A

Party B

InterceptorNetwork

Receiver decrypts the messageUsing the same encryption message

And the same symmetric key

Encrypted Message


Public Key Encryption for Confidentiality

EncryptedMessage

EncryptedMessage

Party A Party B

Encrypt withParty B’s Public Key

Decrypt withParty B’s Private Key

Decrypt withParty A’s Private Key

Encrypt withParty A’s Public Key

Note:Four keys are used to encryptand decrypt in both directions

Figure 9-21: Other Aspects of Protection

Hardening Servers and Client PCs

Setting up computers to protect themselves

Server HardeningPatch vulnerabilitiesMinimize applications running on each serverUse host firewallsBackup so that restoration is possible


Hardening Servers and Client PCs Client PC Hardening

As with servers, patching vulnerabilities, minimizing applications, having a firewall, and implementing backup

Also, a good antivirus program that is updated regularly

Client PC users often make errors or sabotage hardening techniques


Vulnerability Testing

Protections are difficult to set up correctly

Vulnerability testing is attacking your system yourself or through a consultant

There must be follow-up to fix vulnerabilities that are discovered

Incident Response

Dealing with attacks that succeed

Figure 9-22: Incident Response

Response Phases Detecting the attack

If not detected, damage will continue unabated

IDS or employee reports are common ways to detect attacks

Stopping the attackDepends on the attackReconfiguring firewalls may

work


Response Phase Repairing the damage

Sometimes as simple as running a cleanup utility

Sometimes, must reformat a server disk and reinstall software

Can be very expensive if the attacker has done much damage


Response Phase Punishing the attackers

Easier to punish employees than remote attackers

Forensic tools collect data in a manner suitable for legal proceedings


Major Attacks and CSIRTs

Major attacks cannot be handled by the on-duty staff

On-duty staff convenes the computer security incident response team (CSIRT)

CSIRT has people from security, IT, functional departments, and the legal department


Disasters

Natural and attacker-created disasters

Can stop business continuity (operation)

Data backup and recovery are crucial for disaster response

Dedicated backup facilities versus real-time backup between different sites


Disasters Business continuity recovery is broader

Protecting employees

Maintaining or reestablishing communication

Providing exact procedures to get the most crucial operations working again in correct order

Topics Covered

Topics Covered

A Wide Variety of Attacks Viruses and Worms

Hacking (Break-in)ScanningBreak-InExploitation (delete log files, create backdoors, do

damage)

Denial-of-Service (DoS) Attacks Employee misuse of the Internet Growing in frequency (and viciousness)

Topics Covered

A Wide Variety of Attackers Traditional Attackers

Wizard attackersEmployees and Ex-Employees

Criminals (Exploding)

Cyberterrorists and National Governments

Topics Covered

A Management Issue, not a Technical Issue Technology does not work automatically

Planning Risk analysis

Comprehensive security

Defense in depth

Topics Covered

Authentication and Authorization Authentication servers give consistency

Passwords (weak)

Digital signatures and digital certificatesHigh security but difficult to implement

Biometric authenticationCould eliminate passwordsError rates and deception

Topics Covered

Firewalls Drop and log packets

Packet filter firewalls and ACLs

Stateful firewalls (dominate for main firewalls today)

Application firewalls filter application contentUsually do NOT provide antivirus filtering

Defense in depth with multiple firewalls

IDSs to detect complex attacks

IPSs to stop some complex attacks

Topics Covered

Cryptographic Systems Negotiate security parameters

Authentication

Key exchange

Ongoing communication (dominates)

SSL/TLS Cryptographic system used in e-commerce

Protects HTTP communication

Topics Covered

Encryption for Confidentiality Symmetric key encryption

Both sides use the same symmetric keyDominates because fast and efficient

Public key encryptionEach side has a secret private key and a non-

secret public key

Topics Covered

Hardening Servers and Client PCs Patching vulnerabilities

Minimize applications

Host firewalls

Backup

Clients: antivirus filtering (users may sabotage)

Vulnerability Testing

Topics Covered

Incident Response

Detection, stopping, repair, punishment

CSIRTs for major attacks to big for the on-duty staff to handle

Disaster response and business continuity recovery

Hands-On: Windows XP Home Security

Chapter 9a

Copyright 2004 Prentice-HallPanko’s Business Data Networks and Telecommunications, 5th edition

Figure 9a-1: Windows Updates (Study Figure)

The Need for Windows Updates To patch security vulnerabilities

To fix bugs and add functionality


Options

Automatic updating turned on by default in Windows XP

Default is to notify user of updates before downloading and installing

Option to download but notify user of the need to install


Options Option to download and install without user

interventionDangerous because problem updates may cause

difficulties for users


Other Matters

Work-arounds (manual) are difficult for end users

Service packs are cumulative collections of updates

Service packs must be installed in order of their creation

Severe updates may be loaded immediately while others wait


Updating Applications

All applications must be updated as well to eliminate security vulnerabilities

If an application is taken over, an attacker may be able to take over the computer

Updating applications is difficult because there are so many of them

Each will have a different method for users to discover, download, and install updates

Figure 9a-3: Antivirus Scanning (Study Figure)

Importance

Viruses are widespread

Every PC needs antivirus software to stop incoming (and outgoing) viruses

Free Anti-virus for UMFK students and staff

http://www.umfk.maine.edu/it/


Using Antivirus Programs Effectively

Virus definitions database and program must be updated frequently

Preferably daily

Program must be configured to work with user’s e-mail, other programs

Antivirus software must be selected to work with user’s applications, including peer-to-peer


User Subversion

Turning off antivirus programs to reduce problems, work faster

Turning off (or not turning on) automatic updating

Failing to pay for subscription extensions

Figure 9a-4: Network and Internet Connections Dialog Box

Figure 9a-5: Internet Options Dialog Box Security Tab

Security tab of Internet Options dialog box

URLs are automatically treated as part of your Internet zone

Internet is set to a moderate setting by default

Custom Level… allows you to customize security

Figure 9a-6: Security Settings Dialog Box

Figure 9a-7: Internet Options Dialog Box Privacy Tab

Privacy settings in Internet Options

Uses a slide tab

Default is medium

Figure 9a-8: Network Connections Dialog Box

Figure 9a-9: Internet Connection Properties Dialog Box

Figure 9a-10: Options in Advanced TCP/IP Settings Dialog Box

Figure 9a-11: TCP/IP Filtering Configuration

Would check Enable box to enable TCP/IP filtering

Figure 9a-12: Malware Scanning Programs (Study Figure)

Malware Evil software

Viruses and worms

Trojan horses

Spyware (reports personal information to outside parties)

Gets onto client PCs despite security precautions

Figure 9a-12: Malware Scanning Programs (Study Figure)

Malware Scanning Programs Scan for Malware

Usually find malware

Must be updated

More info

http://perleybrook.umfk.maine.edu/slides/spring%202005/cos125/Keeping%20Your%20PC%20Spyware%20Free.pdf

Anti-Spyware Applications

http://perleybrook.umfk.maine.edu/slides/spring%202005/cos125/spyware%20stuff/

Figure 9a-13: Two Connections for Windows XP VPN

SecurityServer

at RemoteSite1.

InternetConnection

2. VPNConnection

Internet

To create a VPN, you create two connectionsOne to the Internet

One to the host you are trying to reach

Figure 9a-14: Connection Screen for a VPN

Figure 9a-15: VPN Properties Dialog Box

Figure 9a-16: Advanced VPN Security Settings

VPN will use MS-CHAP or MS-CHAP v 2 for authentication

Bad because original MS-CHAP had serious security

weaknesses

Figure 9a-17: Windows Domain

Client PC

Client PCMember Server

DomainController

GPO

GroupPolicy Object

(GPO)

Domain

GPO

With Windows XP Professional, client PCSecurity settings can be set on a domain controller

Group Policy Object (GPO) specifies settings

Documents

COS 338 Day 18. DAY 18 Agenda Second capstone progress report over due Lab 5 graded 1 A, 2 B’s, 2 F’s and 1 non-submits Assignment 5 Graded 2 A’s, 2 B’s