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OSS711S - OPERATING SYSTEMS SECURITY - 1ST OPP - JUNE 2023 |
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'9
nAmlBIA UnlVERSITY
OF SCIEnCE Ano TECHnOLOGY
FACULTY OF COMPUTING AND INFORMATICS
DEPARTMENT OF CYBERSECURITY
QUALIFICATION : BACHELOR OF COMPUTER SCIENCEin CYBERSECURITY
QUALIFICATION CODE: 07BCCY, 07BCCS
LEVEL: 7
COURSE: OPERATING SYSTEMSSECURITY
COURSE CODE: 057115
DATE: JUNE 2023
DURATION: 3 Hours
SESSION: 1
MARKS: 100
EXAMINER (5)
FIRST OPPORTUNITY EXAMINATION QUESTION PAPER
MR. ISAAC NHAMU
MODERATOR
DR. NALINA SURESH
THIS EXAM QUESTION PAPER CONSISTS OF 6 PAGES
(Excluding this front page)
INSTRUCTIONS
1. Answer ALL the questions on the answer scripts.
2. Write clearly and neatly.
3. Number the answers clearly.
4. When answering questions you should be guided
few or too many facts in your answers.
by the allocation
of marks in [ ]. Do not give too
PERMISSIBLE MATERIALS
1. None.
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Section A (Multiple Choice)
[15 marks]
1. A buffer-overflow attack can gain accessto a system's memory. (True or false)
2. A smart card is an authentication example using the something you know factor. (True or false)
3. If users forget their password, they can reset the password with a-----~
they created it before forgetting their password.
as long as
4. Permissions assigned at the drive level are inherited by all root folders on the drive. (True or
false)
5. Permissions are retained when you move a file within the same partition. Any other time you
move or copy files, the original permissions are lost. (True or false)
6. MBSA can detect weak passwords for accounts on Microsoft systems. (True or false)
7. In Linux systems, regular (non-administrator) users can view the etcpasswdfile. (True or false)
8. What is meant by reducing the attack surface of a system?
A. Disabling the anti-virus
B. Removing unneeded protocols
C. Keeping a system up to date
D. Disabling the firewall
9. Elizabeth is a member of the Finance group and the Budget group. The Finance group is
granted Modify permission for an NTFSfolder called Funding. The Budget group is granted
Read permission for the same folder. What is Maria's permission to the Funding folder?
A. Impossible to determine.
B. Read
C. Modify
D. Full Control
10. Which Audit Policy selection records any time a user logs onto a local system?
A. Logan Events
B. Account Logan Events
C. System Events
D. ProcessTracking
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11. Which of the following choices can be used to automatically collect events on a single server
from multiple servers?
A. ProcessTracking Events auditing
B. MBSA
C. Automatic archiving
D. Event subscriptions
12. Which one of the following is not a valid use of a digital certificate?
A. Authentication
B. Encryption
C. Digital signatures
D. Virus detection
13. What is known as sandbox?
A. It is a program which can be molded to do desired.task.
B. It is program that is controlled or emulated section of OS
C. It is a special mode of antivirus
D. None of the mentioned
14. Why is a one-time password safe?
A. It is easy to generate.
B. It cannot be shared.
C. It is different for every access.
D. It is a complex encrypted password.
15. What does the value 7 represent in the following line from the etcshadow file?
sync:*:16484:0:99999:7:::
A. The date of last password change field
B. The minimum password age field
C. The maximum password age field
D. The password warning period field
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Section B (Structured Questions)
Question 1
a. Explain the suitability or unsuitability of the following passwords:
i. Rachel123
ii. Windhoek
iii. tv9cartoon#
iv. oneloveafrica
[55 marks]
[4]
b. While trying to improve the security of an organisation through an operating system,
explain what the problem could be of;
i. Increasing the complexity of a password
ii. Setting the password age to one month
iii. Enforcing a password history policy that sets the value larger than 24?[6]
Question 2
a. State three threats that result from a process running with administrator or root
privileges on a system.
[6]
b. List two ways in which security misconfigurations can occur during operating systems
installation.
[2]
a. Give an example each, of weaknesses/vulnerabilities that may affect the operating
system that are caused by;
i. Software
[1]
ii. Policy/Procedures.
[1]
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Question 3
Figure 1 below shows the architecture of Type I and Type II virtual machine systems. From a
security perspective outline three advantages of Type I virtual machine systems over Type II
systems and two advantages of Type II virtual machine systems over Type I systems.
[10]
GuestVM
(
GuestApps
)
( ) GuestOS (Windows)
GuestVM
(
GuestApps
)
( ) GuestOS (Limn:)
(
Virtual l\\Iachine Monitor
)
(
Hardware
)
1!..rchitecturoef Type I \\71:lSy~tems
GuestVJ.,.f
GuestApps
( ) I I (Gues1OS (Limn:))
Host Apps (e.g. Web
Browse1·, Emacs)
( ) ) VMlvI
Host OperatingSystem
(
Hardwatt
)
Architemrre of Type II VJ..-SIyste1m
Figure 1: Architecture of Type I and Type II Virtual Machine Systems
Question 4
One way to implement security in an operating system is by way of assigning permissions on
objects to subjections. Figure 2 illustrates a relationship between permissions.
Figure 2: Relationship between permissions in an NTFSsystem
a. What can a user given Full Control do to an object that one given Modify cannot do?
[2]
b. Give an example of an Execute operation.
[2]
c. What is the difference between Write and Modify?
[2]
d. What is the advantage of using Groups to manage permissions and what is one
disadvantage?
[4]
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Question 5
a. State five ways in which a systems administrator can harden an organisation's
operating system.
[5]
b. Name any three tools that can be used to perform audit log in an operating system.
[3]
c. Using an example define Role Based Access control.
[2]
Question 6
Figure 3 below shows the security architecture diagram for iOS.
SOFTWARE
HARDWARE AND FIRMWARE
Kernel
Secure
Enclave
Secure
Element
User Partition
(Encrypted)
Crypto Engine
OS partition
File system
Device Key
Group Key
Apple Root Certificate
Figure 3: Security architecture diagram far iOS
a.
What file system does iOS use?
[1]
b.
With reference to iOS, what is sahdboxing?
[2]
c.
What is the advantage of sandboxing?
[2]
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Section A (Scenarios and Practice)
(30 marks]
Question 7
A university has realized that they do not have sufficient ICT resources to cater for their ever-
increasing population of students. They have decided to allow staff and students at the
university to bring they own devices (BYOD} to complement their limited resources so as to
facilitate a more conducive teaching and learning environment.
Outline at least ten policy items that systems administrators should enforce at the operating
systems level to protect the university's production system from the BYOD phenomenon, as
well as to protect the staff/students' devices.
[20]
Question 8
According to Android Authority, an independent online publication that is a voice for the
world of Android & technology,
"Whether iOS is better than Android in security is now up for debate, but the consensus
still gives Apple the upper hand." ... making it harder for attackers to target iOS users.
Based on the argument above and from an operating systems perspective. Outline at least
five reasons why devices running iOS are considered better than those running Android.
[10]
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