Chapter 8: The Print Server Role

Published: December 31, 2003   |   Updated: April 26, 2006

Overview

This chapter focuses on how to harden print servers that run Microsoft® Windows Server™ 2003 with SP1, which can be a challenge. The essential services that these servers provide are ones that require the Server Message Block (SMB) and Common Internet File System (CIFS) protocols, both of which can provide rich information to unauthenticated users. These protocols are often disabled on print servers in high-security Windows environments. However, it will be difficult for both administrators and users to access print servers if these protocols are disabled in your environment.

Most of the settings in this chapter are configured and applied through Group Policy. A Group Policy object (GPO) that complements the Member Server Baseline Policy (MSBP) can be linked to the appropriate organizational units (OUs) that contain the print servers to provide the required security settings for this server role. This chapter only discusses those policy settings that vary from the MSBP.

Where possible, these settings are gathered in an incremental Group Policy template that will be applied to the Print Servers OU. Some of the settings in this chapter cannot be applied through Group Policy. Detailed information about how to configure these settings manually is provided.

The following table shows the names of the print server security templates for the three environments that are defined in this guide. These templates provide the policy settings for the incremental Print Server template, which in turn is used to create a new GPO that is linked to the Print Servers OU in the appropriate environment. Step-by-step instructions are provided in Chapter 2, "Windows Server 2003 Hardening Mechanisms" to help you create the OUs and Group Policies and then import the appropriate security template into each GPO.

Table 8.1 Print Server Security Templates for All Three Environments

For information about settings in the MSBP, see Chapter 4, “The Member Server Baseline Policy.” For information on all default settings, see the companion guide, Threats and Countermeasures: Security Settings in Windows Server 2003 and Windows XP, which is available at https://go.microsoft.com/fwlink/?LinkId=15159.

Note: Print servers that are secured with the SSLF-Print Server.inf security template can only be accessed reliably by client computers that are secured with compatible settings. See the Windows XP Security Guide for information about how to secure client computers with SSLF-compatible settings.

Audit Policy Settings

The Audit policy settings for print servers in the three environments that are defined in this guide are configured through the MSBP. For more information about the MSBP, see Chapter 4, "The Member Server Baseline Policy." The MSBP settings activate logging for security audit information on all print servers.

User Rights Assignments

The user rights assignment settings for print servers in the three environments that are defined in this guide are configured through the MSBP. For more information about the MSBP, see Chapter 4, "The Member Server Baseline Policy." The MSBP settings uniformly configure user rights assignments on all print servers.

Security Options

Most security option settings for print servers in the three environments that are defined in this guide are configured through the MSBP. For more information about MSBP, see Chapter 4, "The Member Server Baseline Policy." Differences between the MSBP and the Print Server Group Policy are described in the following section.

Microsoft network server: Digitally sign communications (always)

Table 8.2 Recommended Settings for Digitally Signing Communications (Always)

This policy setting determines whether packet signing is required by the SMB server component. The SMB protocol provides the basis for Microsoft file and print sharing and many other network operations, such as remote Windows administration. To prevent man-in-the-middle attacks that modify SMB packets in transit, the SMB protocol supports SMB packet digital signing. This policy setting determines whether SMB packet signing must be negotiated before further communication with an SMB client is permitted.

Although the Microsoft network server: Digitally sign communications (always) setting is disabled by default, the MSBP enables this setting for servers in the SSLF environment, which allows users to print but not view the print queue. Users who attempt to view the print queue will see an access denied message.

The Microsoft network server: Digitally sign communications (always) setting is configured to Disabled for print servers in all three environments that are defined in this guide.

Event Log Settings

The event log settings for print servers in the three environments that are defined in this guide are configured through the MSBP. For more information about the MSBP, see Chapter 4, "The Member Server Baseline Policy."

Additional Security Settings

Although the security settings applied through the MSBP significantly enhance the security of print servers, there are a few additional settings that you should consider. The settings in this section cannot be applied through Group Policy and must therefore be performed manually on all print servers.

Securing Well-Known Accounts

Microsoft Windows Server 2003 with SP1 has a number of built-in user accounts that cannot be deleted but can be renamed. Two of the most well-known built-in accounts in Windows Server 2003 are Guest and Administrator.

By default, the Guest account is disabled on member servers and domain controllers. This configuration should not be changed. Many variations of malicious code use the built-in Administrator account in an initial attempt to compromise a server. Therefore, you should rename the built-in Administrator account and alter its description to help prevent compromise of remote servers by attackers who try to use this well-known account.

The value of this configuration change has diminished over the past few years since the release of attack tools that specify the security identifier (SID) of the built-in Administrator account to determine its true name and then break into the server. A SID is the value that uniquely identifies each user, group, computer account, and logon session on a network. It is not possible to change the SID of this built-in account. However, your operations groups can easily monitor attempted attacks against this Administrator account if you rename it with a unique name.

To secure well known accounts on print servers

• Rename the Administrator and Guest accounts, and then change their passwords to long and complex values on every domain and server.
• Use different names and passwords on each server. If the same account names and passwords are used on all domains and servers, an attacker who gains access to one member server will be able to gain access to all others.
• Change the account descriptions to something other than the defaults to help prevent easy identification of the accounts.
• Record any changes that you make in a secure location.

Note: You can rename the built-in Administrator account through Group Policy. This setting was not implemented in any of the security templates that are provided with this guide because every organization should choose a unique name for this account. However, the Accounts: Rename administrator account setting can be configured to rename administrator accounts in all three environments that are defined in this guide. This policy setting is a part of the Security Options settings of a GPO.

Securing Service Accounts

Never configure a service to run under the security context of a domain account unless it is unavoidable. If the server is physically compromised, domain account passwords could be easily obtained by dumping LSA secrets. For more information about how to secure service accounts, see The Services and Service Accounts Security Planning Guide at https://go.microsoft.com/fwlink/?LinkId=41311.

Creating the Policy Using SCW

To deploy the necessary security settings, you must use both the Security Configuration Wizard (SCW) and the security templates that are included with the downloadable version of this guide to create a server policy.

When you create your own policy, be sure to skip the "Registry Settings" and “Audit Policy” sections. These settings are provided by the security templates for your chosen environment. This approach is necessary to ensure that the policy elements that are provided by the templates take precedence over those that would be configured by SCW.

You should use a new installation of the operating system to begin your configuration work, which helps ensure that there are no legacy settings or software from previous configurations. If possible, you should use hardware that is similar to the hardware that is used in your deployment to help ensure as much compatibility as possible. The new installation is called a reference computer.

To create the print server policy

1. Create a new installation of Windows Server 2003 with SP1 on a new reference computer.
2. Install the Security Configuration Wizard component on the computer through Control Panel, Add/Remove Programs, Add/Remove Windows Components.
3. Join the computer to the domain, which will apply all security settings from parent OUs.
4. Install and configure only the mandatory applications that will be on every server that shares this role. Examples include role-specific services, software and management agents, tape backup agents, and antivirus or antispyware utilities.
5. Launch the SCW GUI, select Create new policy, and point it to the reference computer.
6. Ensure that the detected server roles are appropriate for your environment, for example the Print server role.
7. Ensure that the detected client features are appropriate for your environment.
8. Ensure that the detected administrative options are appropriate for your environment.
9. Ensure that any additional services that are required by your baseline, such as backup agents or antivirus software, are detected.
10. Decide how to handle unspecified services in your environment. For extra security, you may wish to configure this policy setting to Disable. You should test this configuration before you deploy it to your production network because it may cause problems if your production servers run additional services that are not duplicated on your reference computer.
11. Ensure the Skip this section checkbox is unchecked in the "Network Security" section, and then click Next. The appropriate ports and applications identified earlier are configured as exceptions for Windows Firewall.
12. In the "Registry Settings" section, click the Skip this section checkbox and then click Next. These policy settings are imported from the supplied INF file.
13. In the "Audit Policy" section, click the Skip this section checkbox and then click Next. These policy settings are imported from the supplied INF file.
14. Include the appropriate security template (for example, EC-Print Server.inf).
15. Save the policy with an appropriate name (for example, Print Server.xml).

Test the Policy Using SCW

After you create and save the policy, Microsoft strongly recommends that you deploy it to your test environment. Ideally, your test servers will have the same hardware and software configuration as your production servers. This approach will allow you to find and fix potential problems, such as the presence of unexpected services that are required by specific hardware devices.

Two options are available to test the policy. You can use the native SCW deployment facilities, or deploy the policies through a GPO.

When you start to author your policies, you should consider using the native SCW deployment facilities. You can use SCW to push a policy to a single server at a time, or use Scwcmd to push the policy to a group of servers. The native deployment method offers the advantage of the ability to easily roll back deployed policies from within SCW. This capability can be very useful when you make multiple changes to your policies during the test process.

The policy is tested to ensure that the application of this policy to the target servers will not adversely affect their critical functions. After you apply the configuration changes, you should begin to verify the core functionality of the computer. For example, if the server is configured as a certification authority (CA), ensure that clients can request and obtain certificates, download a certificate revocation list, and so on.

When you are confident in your policy configurations, you can use Scwcmd as shown in the following procedure to convert the policies to GPOs.

For more details about how to test SCW policies, see the Deployment Guide for the Security Configuration Wizard at https://technet2.microsoft.com/WindowsServer/en/Library/5254f8cd-143e-4559-a299-9c723b3669461033.mspx and the Security Configuration Wizard Documentation at https://go.microsoft.com/fwlink/?linkid=43450.

Convert and Deploy the Policy

After you thoroughly test the policy, complete the following steps to convert it into a GPO and deploy it:

1. At the command prompt, type the following command:

   scwcmd transform /p:<i><PathToPolicy.xml> </i>/g:<i><GPODisplayName></i>
   

   and then press ENTER. For example:Note: The line has been split into multiple lines for readability. However, while trying it out on a system you must enter it as one line without breaks.

       scwcmd transform /p:"C:\Windows\Security\msscw\Policies\
       Print Server.xml" /g:"Print Server Policy"
   

   Note: The information to be entered at the command prompt shows on more than one line here because of display limitations. This information should all be entered on one line.

2. Use the Group Policy Management Console to link the newly created GPO to the appropriate OU.

Note that if the SCW security policy file contains Windows Firewall settings, Windows Firewall must be active on the local computer for this procedure to complete successfully. To verify that Windows Firewall is active, open Control Panel and then double-click Windows Firewall.

You should now perform a final test to ensure that the GPO applies the desired settings. To complete this procedure, confirm that the appropriate settings were made and that functionality is not affected.

Summary

This chapter explained the policy settings that can be used for print servers that run Windows Server 2003 with SP1 for the three environments that are defined in this guide. Most of the policy settings are applied through a Group Policy object (GPO) that was designed to complement the MSBP. GPOs can be linked to the appropriate organizational units (OUs) that contain the print servers to provide additional security.

Some policy settings that were discussed cannot be applied through Group Policy. For these policy settings, manual configuration details were provided.

More Information

The following links provide additional information about topics that relate to hardening print servers that run Windows Server 2003 with SP1.

• For an overview of print servers, see the "Technical Overview of Windows Server 2003 Print Services," which is available for download at www.microsoft.com/windowsserver2003/techinfo/overview/print.mspx.
• For more information about print servers, see "What's New in File and Print Services" at www.microsoft.com/windowsserver2003/evaluation/overview/technologies/fileandprint.mspx.