The document provides an overview of computer security and privacy. It discusses the history of computer security from the 1960s to present day, highlighting some famous security problems such as the Morris worm in 1988. It defines key computer security terms and concepts such as threats, vulnerabilities, and countermeasures. It also examines different types of computer security attacks including hacking, denial of service attacks, malware, viruses, worms, and Trojan horses. The document outlines security measures related to physical security, network security, and the importance of the human factor in computer security.

1. Computer Security & Privacy
Chapter 1

2. Computer Security
“The
most secure
computers are those
not connected
to the Internet and
shielded
from any interference”

3. Computer Security
Computer security is about
provisions and policies adopted to
protect information and property
from theft, corruption, or natural
disaster while allowing the
information and property to remain
accessible and productive to its
intended users.

4. Computer Security
Network security on the other hand deals with
provisions and policies adopted to prevent and
monitor unauthorized access, misuse, modification, or
denial of the computer network and network-
accessible resources.
Internet
Not Sufficient!!

5. Computer Security
Security Goals
Integrity
Confidentiality
Availaibility

6. 1) Spoofing Attack
2) Brut Force Attack
3) Malware Attack
4) Virus/Worm Attack
5) SMURF Attack
6) SYN Attack
7) Trojan Horse
8) Logic Bomb
9) Ping of Death
10)Packet Sniffing
11)Eavesdropping
12)Cracking
13)Session Hijacking
14)War Dialing
15)DoS/DDoS
16)Blackout/ Brownout
17)Serge/Spike
18)Traffic Analysis
19)Wire Tapping
Assignment 1 (15%):
• Pick two topics.
• Read about these security
attack related keywords and
write a three page/topic
(maximum) summary of your
findings including any
recorded history of
significant damages created
by these attacks.
• Send your report by email in
pdf format (Use your name as
the file name Ex. Kedir Ali).
• Bonus: While reading, if you
find keywords other than
these, send them on the
second page of your report.
Computer Security

7. Computer Security/ Overview
Security: The prevention and protection of computer
assets from unauthorized access, use, alteration,
degradation, destruction, and other threats.
Privacy: The right of the individual to be protected
against intrusion into his personal life or affairs, or those
of his family, by direct physical means or by publication
of information.
Security/Privacy Threat: Any person, act, or object
that poses a danger to computer security/privacy.
Definitions

8. Computer Security / History
Until 1960s computer security was limited to
physical protection of computers
In the 60s and 70s
 Evolutions
 Computers became interactive
 Multiuser/Multiprogramming was invented
 More and more data started to be stored in computer
databases
Organizations and individuals started to worry about
 What the other persons using computers are doing to their
data
 What is happening to their private data stored in large
databases

9. Computer Security / History
In the 80s and 90s
 Evolutions
 Personal computers were popularized
 LANs and Internet invaded the world
 Applications such as E-commerce, E-government and
E-health started to develop
 Viruses become majors threats
 Organizations and individuals started to worry about
 Who has access to their computers and data
 Whether they can trust a mail, a website, etc.
 Whether their privacy is protected in the connected world

10. Computer Security / History
Famous security problems
 Morris worm – Internet Worm
 November 2, 1988 a worm attacked more than 60,000 computers
around the USA
 The worm attacks computers, and when it has installed itself, it
multiplies itself, freezing the computer
 It exploited UNIX security holes in Sendmail and Finger
 A nationwide effort enabled to solve the problem within 12 hours
Robert Morris became the first person to be indicted
under the Computer Fraud and Abuse Act.
 He was sentenced to three years of probation, 400 hours of
community service and a fine of $10,050
He is currently an associate professor at the
Massachusetts Institute of Technology (MIT)

11. Computer Security / History
Famous security problems …
 NASA shutdown
In 1990, an Australian computer science student was
charged for shutting down NASA’s computer system
for 24 hours
 Airline computers
In 1998, a major travel agency discovered that
someone penetrated its ticketing system and has
printed airline tickets illegally
 Bank theft
In 1984, a bank manager was able to steal $25 million
through un-audited computer transactions

12. Computer Security / History
Famous security problems …
 In Ethiopia
 Employees of a company managed to change their salaries by
fraudulently modifying the company’s database
 In 1990s Internet password theft
Hundreds of dial-up passwords were stolen and sold to other users
Many of the owners lost tens of thousands of Birr each
 A major company suspended the use of a remote login software by
technicians who were looking at the computer of the General
Manager
 In Africa: Cote d’Ivoire
 An employee who has been fired by his company deleted all the
data in his company’s computer

13. Computer Security / History
Early Efforts
1960s: Marked as the beginning of true
computer security
1970s: Tiger teams
Government and industry sponsored crackers who attempted
to break down defenses of computer systems in order to
uncover vulnerabilities so that patches can be developed
1970s: Research and modeling
Identifying security requirements
Formulating security policy models
Defining recommended guidelines and controls
Development of secure systems

14. Computer Security / Legal Issues
In the US, legislation was enacted with regards to
computer security and privacy starting from late
1960s.
European Council adopted a convention on Cyber-
crime in 2001.
The World Summit for Information Society
considered computer security and privacy as a
subject of discussion in 2003 and 2005.
The Ethiopian Penal Code of 2005 has articles on
data and computer related crimes.

15. Computer Security /Attacks
Interruption: An attack on availability
Interception: An attack on confidentiality
Modification: An attack on integrity
Fabrication: An attack on authenticity
Categories of Attacks

16. Computer Security /Attacks
Categories of Attacks/Threats (W. Stallings)
Normal flow of information
Interruption Interception
Modification Fabrication
Source
Destination
Attack

17. Computer Security /Vulnerabilities
Physical vulnerabilities (Ex. Buildings)
Natural vulnerabilities (Ex. Earthquake)
Hardware and Software vulnerabilities (Ex. Failures)
Media vulnerabilities (Ex. Disks can be stolen)
Communication vulnerabilities (Ex. Wires can be tapped)
Human vulnerabilities (Ex. Insiders)
Types of Vulnerabilities

18. Computer Security / Countermeasures
Computer security controls
Authentication (Password, Cards, Biometrics)
(What we know, have, are!)
Encryption
Auditing
Administrative procedures
Standards
Certifications
Physical Security
Laws

19. Computer Security / The Human Factor
The human factor is an important component of
computer security
Some organizations view technical solutions as
“their solutions” for computer security. However:
 Technology is fallible (imperfect)
 Ex. UNIX holes that opened the door for Morris worm
 The technology may not be appropriate
 Ex. It is difficult to define all the security requirements and find a
solution that satisfies those requirements
 Technical solutions are usually (very) expensive
 Ex. Antivirus purchased by ETC to protect its Internet services
 Given all these, someone, a human, has to implement the solution

20. Computer Security / The Human Factor
Competence of the security staff
Ex. Crackers may know more than the security team
Understanding and support of management
Ex. Management does not want to spend money on
security
Staff’s discipline to follow procedures
Ex. Staff members choose simple passwords
Staff members may not be trustworthy
Ex. Bank theft

21. Computer Security / Physical Security
Physical security protects your physical computer
facility (your building, your computer room, your
computer, your disks and other media) [Chuck
Easttom].
Physical security is the use of physical controls to
protect premises, site, facility, building or other
physical asset of an organization [Lawrence Fennelly]

22. Computer Security / Physical Security
In the early days of computing physical security
was simple because computers were big,
standalone, expensive machines
It is almost impossible to move them (not
portable)
They were very few and it is affordable to
spend on physical security for them
Management was willing to spend money
Everybody understands and accepts that there
is restriction

23. Computer Security / Physical Security
Today
Computers are more and more portable (PC, laptop,
PDA, Smartphone)
There are too many of them to have good physical
security for each of them
They are not “too expensive” to justify spending more
money on physical security until a major crisis occurs
Users don’t accept restrictions easily
Accessories (ex. Network components) are not
considered as important for security until there is a
problem
Access to a single computer may endanger many more
computers connected through a network

24. Computer Security / Physical Security
=>
Physical security is much more
difficult to achieve today than some
decades ago
Why?

25. Computer Security / Physical Security
Natural Disasters
 Fire and smoke
 Fire can occur anywhere
 Solution – Minimize risk
Good policies: NO SMOKING, etc..
Fire extinguisher, good procedure and training
Fireproof cases (and other techniques) for backup tapes
Fireproof doors
 Climate
 Heat
 Direct sun
 Humidity
Threats and vulnerabilities

26. Computer Security / Physical Security
Natural Disasters …
 Hurricane, storm, cyclone
 Earthquakes
 Water
 Flooding can occur even when a water tab is not properly closed
 Electric supply
 Voltage fluctuation
Solution: Voltage regulator
 Lightning
Threats and vulnerabilities …
Solution
 Avoid having servers in areas often hit by Natural Disasters!

27. Computer Security / Physical Security
People
Intruders
 Thieves
 People who have been given access unintentionally by the
insiders
 Employees, contractors, etc. who have access to the facilities
 External thieves
 Portable computing devices can be stolen outside the
organization’s premises
Loss of a computing device
Mainly laptop
Threats and vulnerabilities …

28. Computer Security / Physical Security
Safe area
Safe area often is a locked place where
only authorized personnel can have
access
Organizations usually have safe area for
keeping computers and related devices

29. Computer Security / Physical Security
Is the area inaccessible through other openings
(window, roof-ceilings, ventilation hole, etc.)?
Design of the building with security in mind
Know the architecture of your building
Safe area … Challenges
During opening hours, is it always possible to
detect when unauthorized person tries to get to the
safe area?
Surveillance/guards, video-surveillance, automatic-
doors with security code locks, alarms, etc.
Put signs so that everybody sees the safe area

30. Computer Security / Physical Security
Are the locks reliable?
 The effectiveness of locks depends on the design, manufacture,
installation and maintenance of the keys!
 Among the attacks on locks are:
 Illicit keys
Duplicate keys
Avoid access to the key by unauthorized persons even for a few seconds
Change locks/keys frequently
Key management procedure
Lost keys
Notify responsible person when a key is lost
There should be no label on keys
 Circumventing of the internal barriers of the lock
Directly operating the bolt completely bypassing the locking mechanism which remains locked
 Forceful attacks:
Punching, Drilling, Hammering, etc.
Safe area…Locks

31. Computer Security / Physical Security
Surveillance with guards
The most common in Ethiopia
Not always the most reliable since it adds a
lot of human factor
Not always practical for users (employees
don’t like to be questioned by guards
wherever they go)
Safe area… Surveillance

32. Computer Security / Physical Security
Safe area… Surveillance
Surveillance with video
 Uses Closed Circuit Television (CCTV)
 Started in the 1960s
 Become more and more popular with the worldwide increase of
theft and terrorism
 Advantages
 A single person can monitor more than one location
 The intruder doesn’t see the security personnel
 It is cheaper after the initial investment
 It can be recorded and be used for investigation
 Since it can be recorded the security personnel is more careful
 Today’s digital video-surveillance can use advanced techniques such
as face recognition to detect terrorists, wanted people, etc.
 Drawback
 Privacy concerns

33. Computer Security / Physical Security
Choose employees carefully
Personal integrity should be as important a
factor in the hiring process as technical skills
Create an atmosphere in which the levels of
employee loyalty, morale, and job satisfaction
are high
Remind employees, on a regular basis, of
their continuous responsibilities to protect
the organization’s information
Internal Human factor - Personnel

34. Computer Security / Physical Security
Establish procedures for proper destruction and
disposal of obsolete programs, reports, and data
Act defensively when an employee must be
discharged, either for cause or as part of a cost
reduction program
Such an employee should not be allowed access to
the system and should be carefully watched until
he or she leaves the premises
Any passwords used by the former employee
should be immediately disabled
Internal Human factor – Personnel …

35. Computer Security / Attacks & Threats
Computer Security Attacks and
Threats

36. Computer Security / Attacks & Threats
A computer security threat is any person,
act, or object that poses a danger to
computer security
Computer world is full of threats!
… refer to the first assignment…
And so is the real world!
Thieves, pick-pockets, burglars,
murderers, drunk drivers, …

37. Computer Security / Attacks & Threats
What is the right attitude?
 To do what you do in real life
What do you do in real life?
 You learn about the threats
 What are the threats
 How can these threats affect you
 What is the risk for you to be attacked by these threats
 How you can protect yourself from these risks
 How much does the protection cost
 What you can do to limit the damage in case you are attacked
 How you can recover in case you are attacked
 Then, you protect yourself in order to limit the risk but to
continue to live your life
You need to do exactly the same thing with computers!

38. Computer Security / Attacks & Threats
Types of Threats/Attacks … (Chuck Eastom)
Hacking Attack:
Any attempt to gain unauthorized access to
your system
Denial of Service (DoS) Attack
Blocking access from legitimate users
Physical Attack:
Stealing, breaking or damaging of computing
devices

39. Computer Security / Attacks & Threats
Malware Attack:
A generic term for software that has malicious
purpose
Examples
Viruses
Trojan horses
Spy-wares
New ones: Spam/scam, identity theft, e-payment
frauds, etc.
Types of Threats/Attacks (Chuck Eastom)

40. Computer Security /Threats
Viruses
“A small program that replicates and hides itself inside
other programs usually without your knowledge.”
Symantec
Similar to biological virus: Replicates and Spreads
Malware Attack:
Worms
An independent program that reproduces by copying
itself from one computer to another
It can do as much harm as a virus
It often creates denial of service

41. Computer Security /Threats
Trojan horses
(Ancient Greek tale of the city of Troy and the wooden
horse) - ??
Secretly downloading a virus or some other type of mal-
ware on to your computers.
Spy-wares
“A software that literally spies on what you do on your
computer.”
Example: Simple Cookies and Key Loggers
Malware Attack…

42. Computer Security /Threats
Infection mechanisms
First, the virus should search for and detect
objects to infect
Installation into the infectable object
Writing on the boot sector
Add some code to executable programs
Add some code to initialization/auto-executable
programs
Write a macro in a word file
…
Most software based attacks are commonly
called Viruses: How do viruses work?

43. Computer Security /Threats
Trigger mechanism
Date
Number of infections
First use
How do viruses work? …
Effects: It can be anything
A message
Deleting files
Formatting disk
Overloading processor/memory
Etc.

44. Computer Security /Threats
Adolescents
Ethically normal and of average/above
average intelligence.
Tended to understand the difference
between what is right and wrong
Typically do not accept any responsibility
for problems caused
Who Writes Virus

45. Computer Security /Threats
The College Student
Ethically normal
Despite expressing that what is illegal is
“wrong”
Are not typically concerned about the results of
their actions related to their virus writing
Who Writes Virus …
The Adult (smallest category)
Ethically abnormal

46. Computer Security /Threats
Three categories
Scanners
Activity monitors
Change detection software
Anti-Virus
There are
Generic solutions
Ex. Integrity checking
Virus specific solution
Ex. Looking for known viruses

47. Computer Security /Threats
Functions of anti-viruses
Identification of known viruses
Detection of suspected viruses
Blocking of possible viruses
Disinfection of infected objects
Deletion and overwriting of infected
objects
Anti-Virus …

48. Computer Security /Threats
Hacking: is any attempt to intrude or gain
unauthorized access to your system either via
some operating system flaw or other means. The
purpose may or may not be for malicious
purposes.
Hackers/Intrusion Attack:
Cracking: is hacking conducted for malicious purposes.

49. Computer Security /Threats
DoS Attack: is blocking access of legitimate
users to a service.
Denial of Service (DoS) Attack:
Distributed DoS Attack: is accomplished by
tricking routers into attacking a target or using
Zumbie hosts to simultaneously attack a given
target with large number of packets.

50. Computer Security /Threats
Simple illustration of DoS attack (from Easttom)
C:>Ping <address of X> -l 65000 –w 0 -t
Ping
Ping
Ping
Ping
Web Server X
Legitimate User

51. Encryption
Encryption: The conversion of data into
ciphertext, that cannot be easily understood by
unauthorized people.
Decryption: The process of converting
encrypted data back into its original form so
that it can be understood.
Text: Human, readable sequences of characters
Plaintext: What you have before encryption
Ciphertext: Encrypted text
Cipher: Usually refers to the method of encryption

52. The End
Please Ask… or …