Transcript COS 338_day17

COS 338
Day 16
DAY 16 Agenda

Capstone Proposals Overdue


3 accepted, 3 in mediation
Capstone progress reports still overdue

I forgot to mark in calendar so I will grant a reprieve

Second capstone progress report over due

Lab 5 write-up not graded

Will be corrected by next class

Assignment 5 Due

Today we will begin discussing Security
Security
Chapter 9
Copyright 2004 Prentice-Hall
Panko’s Business Data Networks and Telecommunications, 5th edition
Trends in Computer and Network Security
Figure 9-1: CSI/FBI Survey

Survey conducted by the Computer Security
Institute (www.gocsi.com).

Based on replies from 530 U.S. Computer
Security Professionals.

If fewer than twenty firms reported quantified
dollar losses, data for the threat are not shown.

Link to 2005 CSI/FBI Survey
Figure 9-1: CSI/FBI Survey
Had at Least
Percent Percent Number Average
One Security Reporting Reporting Reporting Reported
Incident in
an
an
Quantified Annual
This Category Incident Incident Losses Loss Per
(May Have
in 1997
in 2003
in 2003
Firm
Had Several)
(1000s)
in 1997
Viruses
Insider
Abuse of Net
Access
Average
Reported
Annual
Loss Per
Firm
(1000s)
in 2003
82%
82%
254
$76
$200
Not
Asked
80%
180
Not
Asked
$136
Figure 9-1: CSI/FBI Survey
Had at Least
Percent Percent Number Average
One Security Reporting Reporting Reporting Reported
Incident in
an
an
Quantified Annual
This Category Incident Incident Losses Loss Per
(May Have
in 1997
in 2003
in 2003
Firm
Had Several)
(1000s)
in 1997
Average
Reported
Annual
Loss Per
Firm
(1000s)
in 2003
Laptop Theft
58%
59%
250
$38
$47
Unauthorized
Access
by Insiders
40%
45%
72
Not
Asked
$31
Figure 9-1: CSI/FBI Survey
Had at Least
Percent Percent Number Average
One Security Reporting Reporting Reporting Reported
Incident in
an
an
Quantified Annual
This Category Incident Incident Losses Loss Per
(May Have
in 1997
in 2003
in 2003
Firm
Had Several)
(1000s)
in 1997
Average
Reported
Annual
Loss Per
Firm
(1000s)
in 2003
Denial of
Service
System
Penetration
24%
42%
111
$77
$1,427
20%
36%
88
$132
$56
Sabotage
14%
21%
61
$164
$215
Figure 9-1: CSI/FBI Survey
Had at Least
Percent Percent Number Average
One Security Reporting Reporting Reporting Reported
Incident in
an
an
Quantified Annual
This Category Incident Incident Losses Loss Per
(May Have
in 1997
in 2003
in 2003
Firm
Had Several)
(1000s)
in 1997
Average
Reported
Annual
Loss Per
Firm
(1000s)
in 2003
Theft of
Proprietary
Information
20%
21%
61
$954
$2,700
Financial
Fraud
12%
15%
61
$958
$329
Figure 9-1: CSI/FBI Survey
Had at Least
Percent Percent
One Security Reporting Reporting
Incident in
an
an
This Category Incident Incident
(May Have
in 1997
in 2003
Had Several)
Number
Reporting
Quantified
Losses
in 2003
Average
Reported
Annual
Loss Per
Firm
(1000s)
in 1997
Average
Reported
Annual
Loss Per
Firm
(1000s)
in 2003
Telecom
Fraud
27%
10%
34
Not
Asked
$50
Telecom
Eavesdropping
11%
6%
0
Not
Asked
Not
Asked
3%
1%
0
Not
Asked
Not
Asked
Active
Wiretap
Figure 9-1: CSI/FBI Survey

Conclusion

Attacks are like multiple poisons

Several of them are fatal

Defense is difficult
Major Attacks
Viruses and Worms
Human Hacking (Break-Ins)
Denial-of-Service Attacks
Figure 9-2: Viruses and Worms

Viruses

Pieces of code that attach to other programs

Virus code executes when infected programs
execute

Infect other programs on the computer

Spread to other computers by e-mail attachments,
webpage downloads, etc.
Figure 9-2: Viruses and Worms

Viruses

Many viruses spread themselves by sending fake email messages with infected attachments

Antivirus programs are needed to scan arriving files

Users often fail to keep their computer antivirus
programs up to date

Antivirus filtering on the e-mail server works even if
users are negligent
How Viruses Work
Figure 9-2: Viruses and Worms

Worms

Complete programs

Self-propagating worms identify victim hosts, jump to
them, and install themselves

Can do this because hosts have vulnerabilities

Vendors develop patches for vulnerabilities but
companies often fail to apply them
Figure 9-2: Viruses and Worms


Worms

Worms take advantage of specific vulnerabilities

Firewalls can stop many worms by forbidding access to most ports

E-mail worms can get around antivirus filtering
Famous Worms







Morris worm – the first worm
Code Red – went after IIS servers
Melissa – e-mail worm
Slammer - SQL worm
Blaster – Windows RPC worm
MyDoom – another e-mail worm that creates a BackDoor on your
computer
Figure 9-2: Viruses and Worms

Blended Threats


Combine the spreading characteristics of viruses
and worms
Payloads

Programs that can do damage to infected hosts

Erase hard disks, send users to pornography sites if
they mistype a URL

Trojan horses: exploitation programs disguise
themselves as system files
Figure 9-3: Human Break-Ins (Hacking)


Human Break-Ins:

Viruses and worms rely on one main attack method

Humans can keep trying different approaches until
they succeed
Hacking

Breaking into a computer

Hacking is intentionally using a computer resource
without authorization or in excess of authorization
 Prosecutable if do a certain amount of damage
Figure 9-3: Human Break-Ins (Hacking)

Scanning Phase


Send attack probes to map the network and identify
possible victim hosts

Like a robber casing a neighborhood

Finds active IP addresses

Identifies type of computer at that address via
open ports, etc.
Nmap program is popular (Figure 9-4)
Figure 9-4: Nmap Scanning Output
IP Range
to Scan
Type of
Scan
Identified
Host and
Open
Ports
Figure 9-3: Human Break-Ins (Hacking)

The Exploit

The Term “Exploit” is Used in Two Ways
 The actual break-in
 Exploit is the program used to make the break-in

Super user accounts (administrator and root) can do
anything

If application running with super user privileges is
compromised, the attacker gains super user
privileges
Figure 9-3: Human Break-Ins (Hacking)

After the Break-In

Become invisible by deleting log files
 http://www.rootkit.com/

Create a backdoor (way to get back into the
computer)
 Backdoor account—account with a known
password and super user privileges
 Backdoor program—program to allow reentry;
usually Trojanized

Do damage at leisure
Denial-of-Service (DoS) Attacks

Make a computer or network unavailable to
users

An exploding threat

Rarely: sending a single message to bring
down a computer

Usually: overload a victim with a flood of
messages
Figure 9-5: Distributed Denial-of-Service
(DDoS) Flooding Attack
Attack
Command
Handler
Attacker
1.34.150.37
Zombie
Attack
Command
Attack
Command
Attack
Command
Attack
Packet
Attack
Packet
Victim
60.168.47.47
Zombie
Attack Packet
Handler
Attack
Command
Zombie
Attackers
Figure 9-6: Types of Attackers

Traditional attackers:

Curious hackers

Disgruntled employees and ex-employees

Growing number of criminal attackers

Potential for far more massive attacks

Cyberterror attacks by terrorists

Cyberwar by nations
Security Management
Figure 9-7: Planning Principles

Security is a Management Issue, Not a
Technical Issue

Without good management, technology
cannot be effective.

Like a car. If you don’t know how to drive, not
likely to be able to use effectively.

Soldiers are not just given weapons. Must be
trained extensively in tactics, etc.
Figure 9-7: Planning Principles

Plan-Protect-Respond Cycle

Three phases endlessly repeating

Planning: preparing for defense

Protecting: implementing planned protections

Responding: stopping attacks and repairing
damage when protections fail
Figure 9-7: Planning Principles

Risk Analysis

Cost of protections should not exceed probable
damage

Annual probability of damage

Damage from a successful incident (Say,
$50,000)

Times the annual probability of success (say
10%)

Gives the probable annual loss ($5,000)
Figure 9-7: Planning Principles

Risk Analysis

Cost of protection
 If a protection can reduce the annual probability
of damage by a certain amount, up to this amount
can be spent on the protection

Example
 Protection A can reduce the annual probability of
damage by 50% ($2,500)
 If Protection A costs $1,000 per year, use it.
 If Protection A costs $4,000 per year, don’t use it.
Figure 9-7: Planning Principles

Comprehensive Security

Attacker is intelligent

Attacker only has to find one weakness

Firm needs comprehensive security to close all
avenues of attack
Figure 9-7: Planning Principles

Defense in Depth

Every protection breaks down sometimes

Attacker should have to break through several lines
of defense to succeed

Providing this protection is called defense in depth
Defense
1
(fails)
Defense
2
Authentication
Figure 9-8: Authentication and
Authorization
Authentication
Server
Verifier
1. Credentials
(Password, etc.)
Applicant
Verifier
Applicant
Figure 9-8: Authentication and
Authorization
Authentication
Server
2. OK?
Verifier
Applicant
Verifier
Applicant
Figure 9-8: Authentication and
Authorization
Authentication
Server
Verifier
3. OK and
Authorizations
Verifier
Applicant
Applicant
Figure 9-8: Authentication and
Authorization
Authentication
Server
Verifier
4. Welcome
Verifier
Applicant
Applicant
Figure 9-9: Password Authentication


Passwords

Strings of characters

Typed to authenticate use of a username (account)
on a computer
Benefits

Ease of use for users (familiar)

Inexpensive because built into operating systems
Figure 9-9: Password Authentication


Often weak (easy to crack)

Word and name passwords are common

Can be cracked quickly with dictionary attack
Passwords should be complex

Mix case, digits, and other keyboard characters
($, #, etc.)

Can only be cracked with brute force attacks (trying
all possibilities)
Figure 9-9: Password Authentication


Passwords should be long

Six to eight characters minimum

Each added character increases the brute force
search time by a factor of up to 75
http://www.umfk.maine.edu/password/password
.ppt
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
Figure 9-10: Digital Certificate
Authentication

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 Signature
Digital Certificate
Name of True Party
Public Key of
True Party
Authentication
Digital Signature
Created with
Private Key of
Applicant.
Added to each
Message.
Figure 9-10: Digital Certificate
Authentication

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
Figure 9-10: Digital Certificate
Authentication

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
Figure 9-12: Biometric Authentication

Fingerprint Scanning

Simple and inexpensive

Substantial error rate (misidentification)

Often can be fooled fairly easily by impostors

Dominates biometrics today
Figure 9-12: Biometric Authentication

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.)
Figure 9-12: Biometric Authentication

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
Figure 9-12: Biometric Authentication

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
Permit (Pass)
Legitimate
Packet
Deny
(Drop)
Attack
Packet
Log File
Static
Packet
Filter
Firewall
The Internet
IP-H
TCP-H Application Message
IP-H
UDP-H Application Message
IP-H
ICMP Message
Arriving Packets
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


2. If ICMP Type = 0, PASS


[connection to a public webserver]
[allow incoming echo reply messages]
3. If TCP destination port = 49153 AND 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 AND
65535, PASS


[allow incoming packets to ephemeral UDP port
numbers]
5. DENY ALL

[deny all other packets]
Figure 9-15: Stateful Firewall Default
Operation
Internally initiated
communication
is allowed.
Internal Host
X
Externally
initiated
communication
is stopped.
External
Host
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
Figure 9-16: Application Firewalls

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
Figure 9-16: Application Firewalls

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
Figure 9-16: Application Firewalls

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
Internet
Client
with
Host
Firewall
Software
Application
Firewall
e-mail,
HTTP,
etc.
Main
Firewall:
Stateful
Inspection
Firewall
Screening
Border
Router with
Packet Filter
Firewall
Software
Site
Figure 9-18: Firewalls
Hardened
Server
Allowed Legitimate
Packet
Internet
Firewall
Attacker
IDS
Legitimate
Packet
Hardened
Client PC
Network Management
Console
Log File
Internal
Corporate
Network
Legitimate
Host
Figure 9-18: Firewall
Hardened
Server
Internet
Firewall
IDS
Attack
Packet
Hardened
Client PC
Denied
Attack
Packet
Network Management
Log File
Console
Internal
Corporate
Network
Attacker
Legitimate
Host
Figure 9-18: Intrusion Detection System (IDS)
Hardened Server
Suspicious Packet
Suspicious
Packet
IDS
Hardened
Client
PC
Alarm
About
Suspicious
Packet
Network Management
Console
Log File
IDS
Internal
Corporate
Network
Attacker
Legitimate
Host
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 Traffic
That is SSL/TLS-Aware (Mostly HTTP)
Figure 9-19: Cryptographic System
(SSL/TLS)
Applicant
(Customer Client)
without Digital Certificate
Verifier
(Merchant Webserver)
with Digital Certificate
1.
Negotiation of Security Options (Brief)
2.
Merchant Authenticates Self to Customer
Uses a Digital Certificate
Customer Authentication Is Optional and Uncommon
Figure 9-19: Cryptographic System
(SSL/TLS)
Applicant
(Customer Client)
without Digital Certificate
Verifier
(Merchant Webserver)
with Digital Certificate
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
Figure 9-19: Cryptographic System (SSL/TLS)

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
Symmetric
Key
Message Encryption
Method &
“Hello”
Key
Encrypted Message
Interceptor
Network
Party A
Party B
Encryption uses a
non-secret encryption method and
a secret key
Figure 9-20: Symmetric Key Encryption
and Public Key Encryption
Symmetric Key Encryption for Confidentiality
Symmetric
Key
Encrypted Message
Interceptor
Network
Party A
Encrypted Message
Interceptor cannot read
encrypted messages
Party B
Figure 9-20: Symmetric Key Encryption
and Public Key Encryption
Symmetric Key Encryption for Confidentiality
Symmetric
Key
Message Encryption
Method &
“Hello”
Key
Encrypted Message
Interceptor
Network
Party A
Encrypted Message
Receiver decrypts the message
Using the same encryption message
And the same symmetric key
Same
Symmetric
Key
Decryption Message
Method &
“Hello”
Key
Party B
Figure 9-20: Symmetric Key Encryption
and Public Key Encryption
Public Key Encryption for Confidentiality
Encrypt with
Party B’s Public Key
Party A
Encrypted
Message
Decrypt with
Party B’s Private Key
Note:
Four keys are used to encrypt
and decrypt in both directions
Decrypt with
Party A’s Private Key
Encrypted
Message
Party B
Encrypt with
Party A’s Public Key
Figure 9-21: Other Aspects of Protection

Hardening Servers and Client PCs

Setting up computers to protect themselves

Server Hardening
 Patch vulnerabilities
 Minimize applications running on each server
 Use host firewalls
 Backup so that restoration is possible
Figure 9-21: Other Aspects of Protection

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
Figure 9-21: Other Aspects of Protection

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 attack

Depends on the attack

Reconfiguring firewalls may
work
Figure 9-22: Incident Response

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
Figure 9-22: Incident Response

Response Phase

Punishing the attackers

Easier to punish
employees than remote
attackers

Forensic tools collect
data in a manner
suitable for legal
proceedings
Figure 9-22: Incident Response

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
Figure 9-22: Incident Response

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
Figure 9-22: Incident Response

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)
 Scanning
 Break-In
 Exploitation (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 attackers
 Employees 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 certificates
 High security but difficult to implement

Biometric authentication
 Could eliminate passwords
 Error 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 content
 Usually 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 key
 Dominates because fast and efficient

Public key encryption
 Each side has a secret private key and a nonsecret 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