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Designing a Security Update Infrastructure

Many of the latest attacks to computers and servers with Microsoft operating systems have succeeded in spite of the fact that the patches to prevent these attacks were available on the Microsoft Web site prior to the attack. The attacker succeeded because the administrator had not yet installed the latest patches. Your design strategy should include a system to automate the installation of patches that are critical to the security of your network. You should be familiar with the tools that Microsoft provides with Windows Server 2003. Designing a security update infrastucture includes

  • Designing a Software Update Services (SUS) infrastructure

  • Designing Group Policy to deploy software updates

  • Designing a strategy for identifying computers that are not up to the current patch level

Designing a Software Update Services Infrastructure

Software Update Services (SUS) is new to Windows Server 2003 but is backward compatible to Windows 2000 servers running Service Pack 2 or higher. It is downloadable from the Microsoft Web site at http://www.microsoft.com/windows2000/windowsupdate/sus/default.asp. You should download and install the SUS101SP1.exe file.

Your server needs to meet the following minimum hardware requirements to become a SUS server:

  • Pentium III 700MHz or higher

  • 512MB RAM

  • 6GB hard disk space

  • Windows 2000 Server with SP2 or later or Windows Server 2003

  • IIS 5.0 or later

  • Internet Explorer 6.0 or later

You can use SUS to update clients running Windows 2000 Professional and Windows XP Professional with the latest service packs. SUS enables an administrator to automatically download, test, approve, and install the latest critical updates and service packs from the Microsoft Windows Update Web site. Figure 3.12 shows the SUS administration site. You need to be familiar with the features of SUS, as identified by Microsoft, including the following:

  • Built-in security

  • Selective content approval

  • Content synchronization options

  • Server-to-server synchronization

  • Multilanguage support

  • Remote administration via Hypertext Transfer Protocol (HTTP) or Hypertext Transfer Protocol Secure (HTTPS)

  • Update status logging

Figure 3.12Figure 3.12 You can manage SUS through a secure Web site.

Built-in Security

This one speaks for itself! You can't enhance security if your enhancement creates holes. The administrative pages of SUS are Web-based through IIS and are restricted to local administrators on the computer that hosts the updates. The synchronization always validates the digital certificates on any downloads to the update server. Any files that are not from Microsoft are automatically deleted.

Selective Content Approval

Updates are first downloaded to the server by running SUS synchronization. These, however, are not automatically available to the computers that have been configured to receive updates from that server. Instead, you can approve the updates before they are made available for download. This allows you to test the packages before deploying them.

Content Synchronization Options

You receive the latest critical updates and service packs from Microsoft through the process of synchronization. You can set a schedule for automatic synchronization at preset times. Alternatively, you can use the Synchronize Now button to manually synchronize the server.

Server-to-Server Synchronization

You can point your server to another server running Microsoft SUS instead of to the Windows update server. This creates a single point of entry for updates into the network, without requiring that each SUS server download updates from the external Microsoft source. In this way, updates can be more easily distributed across the enterprise.

Multilanguage Support

SUS supports the publishing of updates to multiple operating system language versions. You can configure the list of languages for which you want to download updates. You only need to download the languages that you will use. This greatly increases the speed of synchronization.

Remote Administration via HTTP or HTTPS

The SUS administrative interface is Web-based. This allows you to manage it remotely as if you were sitting in front of the server itself. Remote administration requires Internet Explorer (IE) 5.5 or later.

Update Status Logging

You can specify the address of a Web server to which the Automatic Updates client should send statistics about updates that have been downloaded and installed. These statistics are sent using HTTP. You can access them in the IIS log file of the Web server.

Designing Group Policy to Deploy Software Updates

Now that you've got the latest critical updates for your servers and clients synchronized into your SUS server, how do you get them into the clients and servers themselves? There is a hard way and an easier way. The hard way is to go to each client and manually change the Automatic Update settings within the properties of My Computer.

The easier way is to use Group Policy to change all of the computers that you need to change—simultaneously. You should configure the Group Policy to set the computers to the correct SUS server and then link the policy to the container in which the computer objects are located. You can configure those computers to automatically download and install the software or to notify the clients and let them make the decision to download and install it. Figures 3.13 and 3.14 show the Group Policy settings for SUS updates. To configure a Group Policy for SUS, perform the following steps:

  1. Open the Group Policy Management Console (GPMC) or Group Policy tool.

  2. Expand Computer Configuration in the properties of the policy.

  3. Expand Administrative Templates.

  4. Expand Windows Update.

  5. Right-click Configure Automatic Updates to configure the settings for each computer.

  6. Right-click Specify Intranet Microsoft Update Service Location to configure the server from which to receive the updates.

Figure 3.13Figure 3.13 You can configure how and when clients receive updates.

Figure 3.14Figure 3.14 You can configure the server from which the client receives the updates.

Designing a Strategy for Identifying Computers That Are Not Up to the Current Patch Level

To provide a complete security plan, you need to make certain that all of your computers have the latest patches and security updates installed. You have many tools to choose from to assist you in scanning computers for the latest updates. These are available from Microsoft and other third parties. The Microsoft tools with which you should be familiar include the following:

  • Microsoft Baseline Security Analyzer

  • Systems Management Server (SMS) and the SUS Feature Pack

Microsoft Baseline Security Analyzer

You can use Microsoft Baseline Security Analyzer (MBSA) to scan for security-related updates on multiple computers. MBSA Version 1.1.1 includes both a GUI tool and a command-line interface tool. You can use these tools to perform scans of Windows systems on your network. MBSA runs on Windows 2000, Windows XP, and Windows Server 2003 systems. You can perform scans of all Windows NT-based clients, including Windows NT Workstation and all later clients. You can also scan for updates to applications running on the clients, including Internet Explorer and Office applications, such as Office 2000 and later. The computer being scanned must be running IE 5.01 or later and XML parser software. Parser software can be downloaded from the Microsoft Web site at http://www.microsoft.com/downloads.

Systems Management Server and SUS Feature Pack

Systems Management Server (SMS) and the SUS feature pack enable you to manage security updates throughout any size company. The SUS feature pack streamlines the security patch management process for you. The SMS software can be used to customize installations.

The Security Update Inventory Tool in SMS uses the MBSA program to scan all of the clients and servers and then creates a detailed Web-based inventory report. Then, you can use the software distribution features built in to SMS to distribute the required software to the clients and servers. The wizards built in to the tool ensure that only the updates that are missing are installed. No redundant or unnecessary updates are performed.

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