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OSS711S - OPERATING SYSTEMS SECURITY - 2ND OPP - JULY 2023 |
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nAm I BI A un IVE RS ITV
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: OS711S
DATE: JULY 2023
DURATION: 3 Hours
SESSION: 2
MARKS: 100
SECOND OPPORTUNITY/SUPPLEMENTARY EXAMINATION QUESTION PAPER
EXAMINER (S)
MR. ISAAC NHAMU
MODERATOR
DR. NALINA SURESH
THIS EXAM QUESTION PAPER CONSISTS OF 5 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)
1. You can enforce a password policy through Group Policy. (True or false)
[15 marks]
2. Any permission explicitly assigned to an object is retained when you remove inherited
permissions. (True or false)
3. If you want to audit all accessto a folder, all you have to do is enable Object Accessauditing
in the Audit Policy. (True or false)
4. If you want to ensure that an audit-log entry records each time a system is shut down, you
should enable Successful entries for ______
auditing.
5. You can secure audit logs with WORM media. (True or false)
6. lffiles are encrypted on a server using EFS,they're automatically encrypted when a user
uses offline folders. (True or false)
7. Fill in the missing option so the user of the bob account can't change his password:
passwd __ 99999 -M 99998 bob
8. What tool can you use to create a comprehensive security policy as an XML file on a
Windows Server system?
A. Microsoft Baseline Security Analyzer (MBSA}
B. System Center Configuration Manager (SCCM}
C. Security Configuration Wizard (SCW}
D. Windows Server Update Services (WSUS}
9. What is the difference between identification and authentication?
A. Nothing. They're the same.
B. Identification proves an identity.
C. Authentication proves an identity.
D. Identification authenticates an individual, and authentication provides
authorization.
10. Of the following choices, what isn't a valid use of a RADIUSserver?
A. Authenticate VPN clients.
B. Authenticate wireless clients.
C. Provide port-based authentication.
D. Provide authentication for 802x database servers.
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11. Which Audit Policy selection records modifications to Active Directory?
A. Privilege Use
B. Account Management Events
C. Directory Service Access
D. Policy Change
12. The operating system's role in the protection of the system from physical threats involves:
A. providing tools to enable system firewall deployments.
B. providing port scanning mechanisms.
C. providing tools to enable system backups and restoration of the OS itself, files,
programs and data.
D. triggering denial of service attacks to prevent malicious users from using the system.
13. What is not a good practice for user administration?
A. Isolating a system after a compromise.
B. Performing random auditing procedures.
C. Granting privileges on a per host basis.
D. Using telnet and FTPfor remote access.
14. Which of the following is a security-based Linux distribution?
A. Fedora
B. CentOS
C. Debian
D. Kali
15. Which command can be used to find users who have no password?
A. find
B. grep
C. passwd
D. search
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Section B (Structured Questions)
[55 marks]
Question 1
One of the important tasks when securing an operating system is to manage passwords.
Outline five different way passwords can be attacked. For each of the attacks you state,
provide a mechanism that can be used to protect against such attacks.
[10]
Question 2
Giving examples, explain how each of the following access control models work and give two
advantages of each.
a. Discretionary Access Control.
[4]
b. Mandatory Access Control.
[3]
c. Role Based Access Control.
[3]
Question 3
For each of the security goals below give two ways/techniques that an operating system can
use to enforce each one of them.
[10]
a. Confidentiality
b. Integrity
c. Availability
d. Non-repudiation
e. Privacy
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Question 4
Figure 1 below illustrates a buffer overflow vulnerability.
Memory
ProgramBuffer
Unexpecteddata
andcode
101010110010
Memory
ProgramBuffer
Othemr emory
unavailabtole
theprogram
1100111011000
Overfloiwnto
othemr emory
Memorpyrotected
beforoeverflow
Memoruynprotected
afteroverflow
Figure 1: //lustration of buffer overflow vulnerability.
a. Using the illustration above, explain what a buffer overflow attack is. [4]
b. Give three ways by which buffer overflow attack can be mitigated.
[6]
Question 5
a. In Linux compare what the etcshadow file and the etcpasswd file store.
[2]
b. Is the etcshadow file viewable by non- administrative users?
[1]
c. Below is a demonstration of part of a typical etcshadow file.
root@onecoursesource:~#
head etcshadow
root:$6$5rU9Z/H5$sZM3MRyHS24SR/ySv80Viqirzfhh.plEWfOic7NzA2zvSjquFKi
PgIVJy8/ba.X/mEQ9DUwtQQb2zdSPsEwb8.
:17320:0:99999:7:
::
daemon:*:16484:0:99999:7:
::
bin:*:16484:0:99999:7:
::
sys:*:16484:0:99999:7:::
sync:*:16484:0:99999:7:
::
games:*:16484:0:99999:7:::
man:*:16484:0:99999:7:::
lp:*:16484:0:99999:7:::
mail:*:16484:0:99999:7:
::
bob:*:16484:3:90:5:30:16584:
using the bob:*:16484:3:90:5:30:: 16584 line as an example describe the
information each field holds.
[7]
Question 6
Describe five way of securing audit logs in an operating system.
[5]
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Section A (Scenarios and Practice)
[30 marks]
Question 7
According to Kaspersky, many businesses are converting their hardware assets to virtual. The main
business goal in most cases is almost certainly to gain maximum efficiency from IT infrastructure.
Running several virtual machines (VMs) together on a single computer instead of using dedicated
servers, all demanding their own power, cooling and maintenance, makes for a convincing argument.
Multiple virtualized nodes powered by a single physical server creates business savings.The economic
effect of virtualization can be amazingly powerful. However, whenever new technology emerges there
are pros and cons of its utilisation.
In terms of operating systems security, Outline at least five security concerns and five security
benefits of adapting virtualisation.
[20]
Question 8
Outline at least five security problems that may hamper the provisioning of services on the
cloud.
[10]
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