INFA 630

 Intrusion Detection and Intrusion Prevention

Dr. Stephen Gantz, CISSP-ISSAP, CEH, CRISC, CIPP/G, C|CISO

Midterm Exam

Summer 2017

Instructions

You are to take this test during the week of June 26 – July 2, 2017. Work alone. You may not confer with other class members, or anyone else, directly or by e-mail or otherwise, regarding the questions, issues, or your answers. You may use your notes, textbooks, other published materials, the LEO site for this class, and the Internet.

The test is worth 25% of your grade for the course. It is scored on the basis of 100 points for the test. The exam is intended to assess your understanding of key concepts in the course, NOT your ability to look up concepts in the textbook or online. Wherever possible, make sure answers are stated in your own words, and where applicable provide your own examples, rather than repeating the ones used in the course materials or other sources (even with attribution).

When composing your answers, be thorough. Please be sure to read each question carefully to be sure you know what is being asked so that you can answer the question completely. The more complete your answer, the higher your score will be. Be sure to identify any assumptions you are making in developing your answers, and describe how your answer would change if the assumptions were different.

While composing your answers, be VERY careful to cite your sources. It is easy to get careless and forget to footnote a source. Remember, failure to cite sources constitutes an academic integrity violation. Use APA style for citations and references.

The test is due no later than 11:59 p.m. Eastern Daylight Time on July 2, 2017. Your answers should be contained in a Microsoft Word, RTF, or compatible format document uploaded to your LEO Assignment folder. Be sure to put your name on the front of your exam. Your instructor will also find it somewhat easier to manage several dozen mid-term documents if you include your name in the title of your saved, completed exam document (e.g., INFA630_midterm_lastname).

General or logistical questions about the exam or these instructions should be posted in the Q&A Conference. Please submit specific or detailed questions regarding the exam to your instructor at stephen.gantz@faculty.umuc.edu.  If questions submitted via email are applicable to all, your instructor will post them in the Midterm   Q&A discussion forum, without revealing their source.

Exam Questions

Part 1: True or False Questions. (10 questions at 1 point each)

1.            T  F      Anomaly-based intrusion detection systems generate alerts based on deviations from “normal” traffic.   Answer: _____

2.            T  F      A host-based IDS monitors traffic on a network that is destined for a particular computer or device.   Answer: ____

3.            T  F      When discussing IDS and IPS, a signature is a digital certificate used to identify the author of an exploit.   Answer: _____

4.            T  F     The success of stateful protocol analysis depends on vendors adhering to standard protocol models that specify expected protocol behavior.   Answer: _____

5.            T  F     Signature-based intrusion detection cannot identify previously unknown attacks.   Answer: _____

6.            T  F      The main difference between network-based IDS and IPS is that IPS responds to suspected attacks by blocking network traffic, while IDS provides notification if suspicious traffic is observed but allows the traffic to pass.   Answer: _____

7.            T  F      Snort requires the use of at least one preprocessor to be able to analyze patterns in network traffic spanning multiple packets.   Answer: _____

8.            T  F      Snort generates an alert every time a detection rule is matched.   Answer: _____

9.            T  F      A network-based IDS that scans packet traffic to try to match known attack patterns is called a signature-based NIDS.   Answer: _____

10.        T  F      An in-line IDS must have the processing power to handle traffic at least as fast as the bandwidth of the network it monitors, or it will lose packets and potentially fail to notify on packets matching alert rules.   Answer: _____

Part 2: Multiple Choice Questions. Print the correct answer in the blank following the question. (Scored as 2 points for each question; there is exactly one correct choice for each question.)  (5 questions at 2 points each)

1. Which of the following is an advantage of anomaly-based detection?

a.       Rules are easy to define

b.      The data it produces can be easily analyzed

c.       It can detect “zero-day” or previously unknown attacks

d.      Malicious activity that falls within normal usage patterns is detected

e.       Rules developed at one site can be shared with many other users

Answer(s): ____

2. Most commercial NIDS tools generate alerts based on signatures at the network layer and what other OSI model layer?

1. Application layer
2. Presentation layer
3. Data-link layer
4. Transport layer
5. Session layer

Answer(s): _____

3. Potential uses for intrusion detection and prevention systems include all of the following EXCEPT?

a.       Initiating incident response procedures

b.      Notifying system administrators when patches need to be applied

c.       Deterring employees from acting in ways that violate security policy

d.      Recording information about the threats faced by an organization’s network  

e.       Verifying the effectiveness of firewall rules in filtering traffic

Answer(s): _____

4. Which is/are true for intrusion protection systems (IPSes)?

a.       An IPS detects network attacks and issues alerts

b.      An IPS can respond to network attacks by blocking traffic and resetting connections

c.       An IPS is typically deployed inline to monitor traffic

d.      a and b only

e.       a, b, and c

Answer(s): _____

5. Which of the following is a limitation of Snort?

a.       Cannot be centrally monitored with sensors running on different OSes

b.      Cannot protect against insider threats

c.       Cannot inspect encrypted traffic for attack signatures

d.      Cannot scale to protect a large network

e.       Cannot detect application-layer attacks

Answer(s): _____

Part 3: Short Answers. Please answer briefly and completely, and cite all sources of information. (6 questions at 10 points each)

1. Identify, describe, and compare the two primary methodologies used by network intrusion detection systems; in other words, the two major ways that NIDS tools work. In your analysis, describe at least three ways in which the two types of NIDS are similar, and at least three ways in which they differ.

2. Identify and briefly describe the two major points of emphasis when developing rules (that is, writing signatures) for network-based IDS tools. Is one approach preferred over the other? Explain why.

3. Describe what a pre-processor does in a network-based IDS tool such as Snort. Demonstrate your understanding of this functionality by citing two examples of pre-processors and explaining what function they serve in the process of network traffic analysis and intrusion detection.

4. If an attacker knew a network-based IDS like Snort was running in a targeted environment, how might the attacker try to penetrate the network while avoiding detection? Provide at least two examples of IDS evasion techniques that might be used by an attacker, and suggest a remedy or defense against the techniques you cite.

5. Describe how a host-based intrusion detection system works, briefly contrasting it with network-based intrusion detection. Explain three types of threats that can be countered effectively by using HIDS tools.

6. Examine the following screen-shot of a short packet capture in Wireshark. Describe the sequence of packets exchanged between the two systems participating in the conversation. What sort of traffic has been captured? What action is occurring in the sequence shown on the screen?

Screen-shot for question 6.

Part 4: IDS Placement. (20 points)  Please refer to the accompanying network diagram as you consider and respond to the following:

Global Corporation, Inc. (GCI) is a fictional company providing business services to a variety of clients across many industries, including commercial and government entities. GCI recently finished construction of a new corporate headquarters, which includes the network infrastructure for primary company operations. You are a security analyst specializing in intrusion detection brought in by GCI to help determine the most appropriate kinds of IDS to use and most effective IDS placements to protect their network.

GCI’s network uses a conventional three-zone architecture:  devices exposed to the Internet are part of an un-trusted outer zone; Internet-accessible services such as the company website and email are in a demilitarized zone; and major systems and servers supporting both Internet-facing and internal applications as well as internal computing resources such as the corporate LAN are in a trusted zone. Each of these zones is segmented from the others using hardware-based firewalls; the corporate databases are further protected behind their own dedicated firewall. GCI allows employees remote access to the corporate LAN using either VPN or dial-up connections.

Identify the locations throughout the GCI network where you would recommend IDS to be deployed. Each of the components in the accompanying GCI-HQ Network diagram is lettered to simplify your references to the diagram. For network connections between devices and layers, you may assume for the purposes of this exercise that all components in a given zone share the same network segment. For each placement you recommend, please note the type of IDS to be deployed and any specific considerations that should be taken into account to ensure the effective monitoring of the location.