Tài liệu Module 11: Creating a Security Design for Network Perimeters ppt

Contents Overview 1 Lesson: Determining Threats and Analyzing Risks to Network Perimeters 2 Lesson: Designing Security for Network Perimeters 8 Lab A: Designing Security for Network Perimeters 17 Module 11: Creating a Security Design for Network Perimeters Information in this document, including URL and other Internet Web site references, is subject to change without notice. Unless otherwise noted, the example companies, organizations, products, domain names, e-mail addresses, logos, people, places, and events depicted herein are fictitious, and no association with any real company, organization, product, domain name, e-mail address, logo, person, place or event is intended or should be inferred. Complying with all applicable copyright laws is the responsibility of the user. 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The names of actual companies and products mentioned herein may be the trademarks of their respective owners. Module 11: Creating a Security Design for Network Perimeters iii Instructor Notes In this module, students will learn how to determine threats and analyze risks to network perimeters. Students will also learn how to design security for network perimeters, including screened subnets, and for computers that connect directly to the Internet. After completing this module, students will be able to: ! Determine threats and analyze risks to network perimeters. ! Design security for network perimeters. To teach this module, you need Microsoft ® PowerPoint ® file 2830A_11.ppt. It is recommended that you use PowerPoint version 2002 or later to display the slides for this course. If you use PowerPoint Viewer or an earlier version of PowerPoint, all of the features of the slides may not be displayed correctly. To prepare for this module: ! Read all of the materials for this module. ! Complete the practices. ! Complete the lab and practice discussing the answers. ! Read the additional reading for this module, located under Additional Reading on the Web page on the Student Materials CD. ! Visit the Web links that are referenced in the module. Presentation: 45 minutes Lab: 30 minutes Required materials Im p ortan t Preparation tasks iv Module 11: Creating a Security Design for Network Perimeters How to Teach This Module This section contains information that will help you to teach this module. Lesson: Determining Threats and Analyzing Risks to Network Perimeters Explain that the perimeter of a network is any entry point into an organization’s network. A screened subnet (which is a type of network perimeter) and a single computer on a network that is directly connected to the Internet are both examples of a network perimeter. Emphasize to students that a network perimeter is more than just a DMZ, demilitarized zone, or screened subnet—it is anything that reaches outside the network that could allow an attacker inside the network. This page is intended simply to give examples of vulnerabilities. To elaborate attacks, draw upon your own experiences. The next page deals with common vulnerabilities, so try not to skip ahead. Explain the vulnerabilities, but do not discuss how to secure against them. The second lesson in the module covers that topic. This practice requires that students have classroom access to the Internet. If students do not have classroom access, simply read the practice answers to them and then ask students if they have experienced such attacks. Lesson: Designing Security for Network Perimeters This section describes the instructional methods for teaching this lesson. Emphasize the additional reading and Web sites referenced throughout the module for additional depth on the topics provided. This page introduces screened subnets. Use this page to reemphasize what the perimeter of a network is. The common designs shown are known by many different names. Emphasize the fact that different parts of a network may be separated from each other by perimeters; for example, a main office and a branch office, or a main network and a test network. Be sure to point students to the ISA Server Installation and Deployment Guide, under Additional Reading on the Web page on the Student Materials CD. This page emphasizes the threats that network computers are under, and the threats to which those computers expose the network when they connect to outside networks. Many students may feel that this module is or is supposed to be about screened subnets; emphasize that an organization’s computer that is connected to an outside network is effectively on the perimeter of the organization’s network, and may present a serious risk to network security. As security designers, students must be aware of the risks involved and design security measures to mitigate against those risks. Answers may vary. Use the security responses that students give to generate classroom discussion. What Is the Perimeter of a Network? Why Perimeter Security Is Important Common Vulnerabilities to Perimeter Securit y Practice: Analyzing Risks to Network Perimeters Common Network Perimeter Desi g ns Guidelines for Protecting Computers on a Perimeter Practice: Risk and Response Module 11: Creating a Security Design for Network Perimeters v Use this page to review the content of the module. Students can use the checklist as a basic job aid. The phases mentioned on the page are from Microsoft Solutions Framework (MSF). Use this page to emphasize that students must perform threat analysis and risk assessment on their own networks for the topic covered in this module, and then they must design security responses to protect the networks. Assessment There are assessments for each lesson, located on the Student Materials compact disc. You can use them as pre-assessments to help students identify areas of difficulty, or you can use them as post-assessments to validate learning. Lab A: Designing Security for Network Perimeters To begin the lab, open Microsoft Internet Explorer and click the name of the lab. Play the video interviews for students, and then instruct students to begin the lab with their lab partners. Give students approximately 20 minutes to complete this lab, and spend about 10 minutes discussing the lab answers as a class. For general lab suggestions, see the Instructor Notes in Module 2, “Creating a Plan for Network Security.” Those notes contain detailed suggestions for facilitating the lab environment used in this course. Customization Information This section identifies the lab setup requirements for a module and the configuration changes that occur on student computers during the labs. This information is provided to assist you in replicating or customizing Microsoft Official Curriculum (MOC) courseware. This module includes only computer-based interactive lab exercises, and as a result, there are no lab setup requirements or configuration changes that affect replication or customization. The lab in this module is also dependent on the classroom configuration that is specified in the Customization Information section at the end of the Automated Classroom Setup Guide for Course 2830A, Designing Security for Microsoft Networks. Lab Setup There are no lab setup requirements that affect replication or customization. Lab Results There are no configuration changes on student computers that affect replication or customization. Security Policy Checklist General lab suggestions Importan t Module 11: Creating a Security Design for Network Perimeters 1 Overview ***************************** ILLEGAL FOR NON - TRAINER USE ****************************** In this module, you will learn how to determine threats and analyze risks to network perimeters. You will also learn how to design security for network perimeters, including screened subnets, and for computers that connect directly to the Internet. After completing this module, you will be able to: ! Determine threats and analyze risks to network perimeters. ! Design security for network perimeters. Introduction Ob j ectives 2 Module 11: Creating a Security Design for Network Perimeters Lesson: Determining Threats and Analyzing Risks to Network Perimeters ***************************** ILLEGAL FOR NON - TRAINER USE ****************************** The perimeter, or boundary, of a network is where your organization ends and the area outside your organization begins. Perimeters are not always easy to identify. Attackers who penetrate weaknesses in your perimeter can potentially access information on your network. After completing this lesson, you will be able to: ! Describe the perimeter of a network. ! Explain the importance of perimeter security. ! List common vulnerabilities to perimeter security. Introduction Lesson objectives Module 11: Creating a Security Design for Network Perimeters 3 What Is the Perimeter of a Network? ***************************** ILLEGAL FOR NON - TRAINER USE ****************************** A perimeter is any point that connects to networks outside of an organization. In a typical network, perimeter points can include: ! Direct Internet connections. Any connection to the Internet from within an organization. ! Dedicated WAN links. Wide area network (WAN) links to branch offices, trusted partners, or other facilities outside of the organization. ! Screened subnets. Protected areas within a network that run services, such as business-to-business (B2B) services, that the organization exposes to public networks, such as the Internet. ! VPN clients. A virtual private network (VPN) tunnel to remote users who are accessing the internal network across a public network. ! Applications. Organizations may run applications that access the Internet or access services running in a screened subnet. ! Wireless connections. Access to wireless networks can often be gained from outside of an organization’s physical facilities. Key points 4 Module 11: Creating a Security Design for Network Perimeters Why Perimeter Security Is Important ***************************** ILLEGAL FOR NON - TRAINER USE ****************************** Assets are vulnerable to threats from both external and internal attackers. For example: An external attacker runs a series of port scans on a network. The attacker uses the information to create a network diagram of the perimeter, including computers in the screened subnet, operating systems of network devices and computers, services running in the screened subnet, and the level of security that is implemented on the network. The attacker researches known vulnerabilities of these network devices, computers, and services, and then attacks the network systematically. An employee receives an e-mail from a friend through an external Web-based e-mail account. When the employee opens a file that is enclosed in the e-mail, a new worm virus automatically spreads to all computers on the internal network. The traffic from the spreading virus slows legitimate traffic, resulting in a denial of service (DoS) for network users. Key points External attacker scenario Internal attacker scenario [...]... applications Any e-mail applications that access the Web can spread viruses because they circumvent the mail servers that use the organization’s firewall ! Additional reading Use and maintain antivirus software Third-party antivirus software can prevent attacks from such threats as viruses, Trojan horse applications, and worms Educate users about security Increasing user awareness through information campaigns... domain Northwind Traders recently deployed a Web server so that employees can retrieve their e-mail messages The IT manager has asked you to explain how a Land attack and a SYN flood attack (or SYN-ACK attack) can prevent users from retrieving their e-mail Use the Internet to locate information about how Land and SYN-ACK attacks affect perimeter security Questions 1 What is a Land attack, and how can... the main network You can use routers and firewalls to screen traffic that goes in and out of a screened subnet Types of network perimeters include: ! Bastion host Acts as the main connection for computers on the internal network that are accessing the Internet As a firewall, the bastion host is designed to defend against attacks that are aimed at the internal network Smaller networks typically use bastion... remain half open The attacker repeatedly changes the spoofed source address on each new packet that is sent to generate additional traffic and deny legitimate traffic An attacker could use a SYN-ACK attack against the router, firewall, or Web server at Northwind Traders to prevent users from retrieving their e-mail messages Sources of information include: • RFC 2267, Defeating Denial of Service Attacks... their email messages? A Land attack sends SYN packets with the same source and destination IP addresses and the same source and destination ports to a host computer This makes it appear as if the host computer sent the packet to itself The host will continue to attempt to contact itself and prevent legitimate traffic from being processed An attacker could use a Land attack against the router, firewall,... Repudiation, Information disclosure, Denial of service, and Elevation of privilege) and life cycle threat models Manage risks Qualitative and quantitative risk analysis Phase Task Details Building Create policies and procedures for securing: Perimeter devices and network perimeters Servers in screened subnets Computers connected to the Internet Module 11: Creating a Security Design for Network Perimeters. .. 17 Lab A: Designing Security for Network Perimeters *****************************ILLEGAL FOR NON-TRAINER USE****************************** Objectives After completing this lab, you will be able to apply security design concepts to network perimeters Scenario You are a consultant hired by Contoso Pharmaceuticals to help the company design security for its network Each lab uses an interactive application... scenario-based information To begin a lab, on the desktop, click Internet Explorer; this opens a Web page that contains links to each lab Click a link to begin a lab Estimated time to complete this lab: 30 minutes Work with a lab partner to perform the lab ! To complete a lab 1 Read Ashley Larson’s e-mail in each lab to determine the goals for the lab 2 Click Reply, and then type your answer to Ashley’s... Click Send to save your answers to a folder on your desktop 4 Discuss your answers as a class 18 Module 11: Creating a Security Design for Network Perimeters Lab A: Designing Security for Network Perimeters Lab Questions and Answers Answers may vary The following are possible answers 1 How would you configure the firewall? Configure the firewall to permit only inbound and outbound File Transfer Protocol... common, an organization’s network often maintained only one connection to a public network Today, Internet access, remote access, and branch office connectivity have become vital to the operation of an organization As organizations increase their requirements for connectivity, the difficulty of managing network connections increases, and so does the risk that information and computers may be exposed to attack . external and internal attackers. For example: An external attacker runs a series of port scans on a network. The attacker uses the information to create a. Unavailable Because of Malicious SYN Attacks. 8 Module 11: Creating a Security Design for Network Perimeters Lesson: Designing Security for