Recent Question/Assignment

(Security and Support in IT, UG/G)
This assessment item contributes 10% of the total marks of this unit and is due on Friday the 25th of October 2019 at 23:59. You should plan and complete your assignment before the deadline. The deadline is the local time of Canberra, Australia. It is your responsibility to correctly adjust your clocks, including the one in Canvas personalized user interface.
Submissions (single MS Word or pdf document) are through Canvas
( Please familiarize yourself with Canvas submissions before the deadline. After you upload your assignment report, please DO NOT FORGET to click the submit button; otherwise, your submitted assignment may remain as a draft.
No other forms of submission will be accepted.
Students can apply for an extension to the submission due date for an assessment item through extenuating, evidenced circumstances (specific details are found through the Assessment Policy and Procedures. Section 9.12). Extensions must be applied for before the due date. Documentary evidence (e.g. medical certificate) will be expected for an extension to be granted, however this will not guarantee that the application will be successful. The Unit Convener or relevant Discipline Convener will decide whether to grant an extension and the length of the extension.
An Assignment Extension form is available from the Student Forms page.
Late submission of assignments without an approved extension will result in a penalty of 5% reduced marks from the total available, per calendar day late. An assignment submitted over 7 days late will not be accepted.
If a student chooses to submit his/her assignment via the Internet off the campus, it is the responsibility of the student to guarantee the accessibility of the Internet. Not being able to access to the Internet at a location which is outside of the campus is not an excuse for extension.
Note: The textbooks are your primary sources of information. [Total marks on this paper 20]
1. [3 marks] Suppose you are responsible for the IT infrastructure of an organization, which has about 15 desktop computers. You are advised that automation for uniformity is a good solution. What does it mean by “automation for uniformity”? Why is it a good solution in principle? Will you implement a fully automatic system in this case of yours? Why or why not.
2. [2 marks] Please summarise the technologies used in server computers to improve reliability, availability, and performance.
3. [2 marks] Please summarise the “Scope of Coverage” of a Helpdesk operation.
4. [3 marks] Suppose that you are responsible for the IT department of a university with students around the world. It is infeasible to meet each student in person. The IT department is responsible for all secure communication with the students. Assume that there is a trusted certificate authority which can securely issue certificates to all involved parties. Please explain:
• Why the trusted certificate authority is essential to establish a secure communication? What role does it play in the secure communication between the IT department and the students?
• From time to time, your department, on behalf of the University, makes public announcements. The announcements are of public nature and can be shared and transmitted by any interested parties, say, prospective students. How would you guarantee the authenticity of your announcements? It is not a solution to publish the announcement on a website for students to compare and decide if the received copies are the same as the web copies.
5. [5 marks] An organization has 2 server computers and a number of desktop computers and a few printers. All of them are connected together via an internal network, and the network is connected to the Internet via the border router of the organization. From the outside of the organization, on the Internet, only these 2 server computers are visible. One of them is the email server (IP address: e1.e2.e3.e4), and the other one is the web server (IP address: w1.w2.w3.w4). In other words, only these 2 server computers accept requesting incoming network traffic. All desktop computers are allowed to access the Internet, without any restriction. Therefore, they accept responding incoming network traffic, but not accepting any requesting incoming network traffic.
• [3 marks] Please design the network and draw the network diagram. You have the freedom to assume the internal network structure. In the diagram, in addition to the 2 servers, you should also include a few desktop computers and a printer. Please explain the rationale on why you put a computer or a printer in its designated location, 1 example for each location. A subnet (or a segment) is regarded as the same location. (hint: a firewall or a few firewalls, depending on your design, are needed to regulate the network traffic)
• [2 mark] Please write down the firewall rules to fulfil the access requirement of the organization. Please also explain the meaning of each firewall rule. If you have multiple firewalls, you should explain to which firewall each of the rules belongs. Below is a set of sample firewall rules. Please follow the sample firewall rule (below) format to write down your firewall rules. Please also be advised that the order of the rules matters.
The meaning of the columns of the sample firewall rules in the screen dump is as follows. Please use only the information provided here and the textbook for your assignment. The information provided here is overly simplified from iptables manual to make the assignment manageable.
• action – ACCEPT means accepting the connection, and REJECT means rejecting the connection.
• prot – the protocol of the connection, e.g., tcp, udp, icmp, and all etc.;
• opt – please ignore;
• source – source IP address of the packet;
• destination – destination IP address of the packet, plus extra information, for example: o “tcp dpt: https” means that the TCP port of the destination host is https.
o state lists the connection state for the firewall to match on to perform the action of the rule. RELATED: the connection is new, but is related to another. connection already permitted; ESTABLISHED: the connection is already established.
o reject-with: please ignore. No need to include this in your assignment.
The textbooks are your reference: Week 1 slides; Stallings: Chapter 9.
6. [5 marks] Please write a summary to briefly explain to senior managers, who know very little on computer security but have a general understanding of IT, on what a buffer overflow problem is and what the consequences of a buffer overflow problem could cause [1 mark]. What programming techniques the software development team should adopt to avoid buffer overflow problems in the software it develops [1 mark].
Below is from a Nessus report on a computer.
• [1 mark] Pretending that the application is developed by the software development team of this organization, how to fix the problem.
• [1 mark] Accepting the recommendations given by the report, what action you should take? Assuming that this computer is one of the many desktop computers, and an automatic system for software updating is in operation. Write down the operational steps, by following the principle of “one, some, and many”.
• [1 mark] Assuming that this computer is a server computer, please write a brief report to the senior managers, who know very little on computer security but have a general understanding of IT, explaining why the software Firefox (a web browser) should not be installed on the computer. In your report, you should use trusted information sources to explain to your senior managers on the best practices of operating system security administration.
The textbook is your reference: Limoncelli: Chapter 1; Stallings: Chapter 9, 10, 11, 12.
7. [0 marks – only for study purposes in preparation for the Assignment Evaluation Quiz] – You may include your response in your submission if you wish but it will not be marked.
Below is a diagram depicting the procedure involved in verifying a password in a UNIX system. What are the three main purposes of using a salt value in storing passwords? Why is a hash function instead of an encryption algorithm preferred in securing the password?
8. [0 marks – only for study purposes in preparation for the Assignment Evaluation Quiz] You may include your response in your submission if you wish but it will not be marked.
Below is a diagram an authentication system using Kerberos servers. Describe the process involved in a registered user logging on to a system to access a file stored on a file server as shown in the diagram below. The system consists of Kerberos servers and a file server.
Assume that a Secret Key is already shared between Ticket Grant Server (TGS) and file server. Please also comment on the type of encryption used between these servers and explain why.