Appendix E: List of Security Settings

This appendix lists the recommended security settings for WSUS. The recommendations are categorized into settings for Windows Server, IIS, and SQL Server.

Windows Server

The following are security recommendations for Windows Server with WSUS.

Audit policy

Enable audit events to ensure that adequate logs are collected for system activities.

Audit policy settings

Option Security setting Setting rationale
Audit account logon events Success, Failure Auditing for successful and failed logon events provides useful data regarding password brute-forcing attempts.
Audit account management Success, Failure Auditing for successful and failed account management events tracks management activities.
Audit directory service access No Auditing This is only important for domain controllers running the Active Directory Domain Services (AD DS).
Audit logon events Success, Failure Auditing for successful and failed logon events provides useful data regarding password brute-forcing attempts.
Audit object access No Auditing Auditing object access is unnecessary and creates many unnecessary logs for WSUS activity.
Audit policy change Success, Failure Auditing for successful and failed policy changes tracks management activities.
Audit privilege use Success, Failure Auditing for successful and failed privilege use tracks administrator activities.
Audit process tracking No Auditing Process-tracking events are unnecessary for WSUS implementations.
Audit system events Success, Failure Auditing for successful and failed system events tracks system activities.

Security options

Configure Windows Server security settings to help ensure optional security and functionality.

Security options settings

Option Security setting Setting rationale
Accounts: Administrator account status Enabled Because it is necessary to have an administrator, the administrator account should be enabled for authorized users.
Accounts: Guest account Status Disabled Because it is risky to have guest accounts, the guest account should be disabled unless specifically required.
Accounts: Limit local account use of blank passwords to console logon only Enabled Accounts with blank passwords significantly increase the likelihood of network-based attacks.
Accounts: Rename administrator account Not Defined Renaming the administrator account forces a malicious individual to guess both the account name and password. Note that even though the account can be renamed, it still uses the same well known SID, and there are tools available to quickly identify this and provide the name.
Accounts: Rename Guest account Not Defined Because the Guest account is disabled by default, and should never be enabled, renaming the account is not important. However, if an organization decides to enable the Guest account and use it, it should be renamed beforehand.
Audit: Audit the access of global system objects Enabled This setting needs to be enabled for auditing to take place in the Event Viewer. The auditing setting can be set to Not Defined, Success or Failure in the Event View.
Audit: Audit the use of backup and restore privilege Enabled For security reasons, this option should be enabled so that auditors will be aware of users creating backups of potentially sensitive data.
Audit: Shut down system immediately if unable to log security audits Disabled Enabling this option shuts down the system if it is unable to log audits. This can help prevent missed audit events. Enabling very large log files on a separate partition helps mitigate this.
Devices: Allow undock without having to log on Disabled Disabling this option ensures that only authenticated users can dock and undock computers.
Devices: Allow to format and eject removable media Administrators This option is not typically useful for desktop images.
Devices: Prevent users from installing printer drivers Enabled Because the Windows GDI system runs in kernel space, allowing a user to install a printer driver could lead to elevated privileges.
Devices: Restrict CD-ROM access to locally logged-on user only Enabled Enabling this option prevents remote users from accessing the local CD-ROM, which may contain sensitive information.
Devices: Restrict floppy access to locally logged-on user only Enabled In situations in which the server is physically secured and password authentication is required by the Recover Console, this option can be enabled to facilitate system recovery.
Devices: Unsigned driver installation behavior Warn but allow installation Most driver software is signed. Administrators should not install unsigned drivers unless the origin and authenticity can be verified and the software has been thoroughly tested in a lab environment first. Because only senior administrators will be working on these systems, it is safe to leave this to their discretion.
Domain controller: Allow server operators to schedule tasks Disabled The ability to schedule tasks should be limited to administrators only.
Domain controller: LDAP server signing requirements Not Defined This option applies only to domain controllers.
Domain controller: Refuse machine account password changes Disabled Enabling this option allows machine accounts to automatically change their passwords.
Domain member: Digitally encrypt or sign secure channel data (always) Disabled If the domain controller is known to support encryption of the secure channel, this option can be enabled to protect against local network attacks.
Domain member: Digitally encrypt secure channel data (when possible) Enabled Enabling this option provides the most flexibility while enabling the highest security when the server supports it.
Domain member: Digitally sign secure channel data (when possible) Enabled Enabling this option provides the most flexibility while enabling the highest security when the server supports it.
Domain member: Disable machine account password changes Disabled Disabling this option allows machine accounts to automatically change their passwords.
Domain member: Maximum machine account password age 30 days Less frequently changed passwords are easier to break than passwords that are changed more frequently.
Domain member: Require strong (Windows 2000 or later) session key Enabled Enabling this option sets strong session keys for all computers running Windows 2000 or later.
Interactive logon: Do not display last user name Enabled Hiding the last user name should be enabled, especially when the administrator user account is renamed. This helps prevent a passerby from determining account names.
Interactive logon: Do not require CTRL+ALT+DEL Disabled The CTRL+ALT+DEL sequence is intercepted at a level lower than user mode programs are allowed to hook. Requiring this sequence at logon is a security feature designed to prevent a Trojan Horse program masquerading as the Windows logon from capturing users' passwords.
Interactive logon: Message text for users attempting to log on [provide legal text] An appropriate legal and warning message should be displayed according to the Corporate Security Policy.
Interactive logon: Message title for users attempting to log on [provide legal title text] An appropriate legal and warning message should be displayed according to the Corporate Security Policy.
Interactive logon: Number of previous logons to cache (in case domain controller is not available) 10 logons This option is usually appropriate only for laptops that might be disconnected from their domain. It also presents a security risk for some types of servers, such as application servers. If a server is compromised and domain logons are cached, the attacker may be able to use this locally stored information to gain domain-level credentials.
Interactive logon: Prompt user to change password before expiration 14 days Password prompts should be aligned according to the Corporate Security Policy.
Interactive logon: Require Domain Controller authentication to unlock workstation Enabled Enabling this option allows a domain controller account to unlock any workstation. This should only be allowed for the local Administrator account on the computer.
Interactive logon: Require smart card Not Defined If this system will not be using smart cards, this option is not necessary.
Interactive logon: Smart card removal behavior Not Defined If this system will not be using smart cards, this option is not necessary.
Microsoft network client: Digitally sign communications (always) Disabled For systems communicating to servers that do not support SMB signing, this option should be disabled. However, if packet authenticity is required, this can be enabled.
Microsoft network client: Digitally sign communications (if server agrees) Enabled For systems communicating to servers that do support SMB signing, this option should be enabled.
Microsoft network client: Send unencrypted password to third-party SMB servers Disabled If this option is enabled, then a third-party SMB server could negotiate a dialect that does not support cryptographic functions. Authentication would be performed using plain-text passwords.
Microsoft network server: Amount of idle time required before suspending session 15 minutes This should be set appropriately for the end-user system such that idle connections do not linger or consume resources.
Microsoft network server: Digitally sign communications (always) Disabled For systems communicating to servers that do not support SMB signing, this option should be disabled. However, if packet authenticity is required, this can be enabled.
Microsoft network server: Digitally sign communications (if client agrees) Enabled For systems communicating to servers that do not support SMB signing, this option should be disabled. However, if packet authenticity is required, this can be enabled.
Microsoft network server: Disconnect clients when logon hours expire Enabled Enabling this option prevents users from logging on after authorized hours.
Network access: Allow anonymous SID/Name translation Disabled This option is highly important for securing Windows networking. Disabling it severely restricts the abilities granted to a user connecting with a Null session.
Network access: Do not allow anonymous enumeration of SAM accounts Enabled This option is highly important for securing Windows networking. Enabling this option severely restricts the abilities granted to a user connecting with a Null session. Because “Everyone” is no longer in the anonymous user’s token, access to IPC$ is disallowed. Pipes that are explicitly set to allow anonymous are inaccessible because the SMB tree connection to this share fails.
Network access: Do not allow anonymous enumeration of SAM accounts and shares Enabled This option is highly important for securing Windows networking. Enabling this option severely restricts the abilities granted to a user connecting with a Null session. Because “Everyone” is no longer in the anonymous user’s token, access to IPC$ is disallowed. Pipes that are explicitly set to allow anonymous are inaccessible because the SMB tree connection to this share fails.
Network access: Do not allow storage of credentials or .NET passports for network authentication Enabled Enabling this option prevents the storage of sensitive passwords in the computers’ cache.
Network access: Let Everyone permissions apply to anonymous users Disabled Anonymous users should have no access to computers.
Network access: Named Pipes that can be accessed anonymously Not Defined Named pipes should be restricted anonymously. Restricting named pipes breaks some intersystem processes, such as network printing.
Network access: Remotely accessible registry paths Not Defined Registry paths should be restricted from remote access unless for monitoring circumstances.
Network access: Shares that can be accessed anonymously None No shares should be accessed anonymously.
Network access: Sharing and security model for local accounts Guest only—local users authenticate as Guest Limit all local accounts to Guest privileges.
Network security: Do not store LAN Manager hash value on next password change Enabled Enabling this feature deletes the weaker LAN Manager hashes, reducing the likelihood of password attacks from sniffing the weak hash over the name or from the local SAM database file.
Network security: Force logoff when logon hours expire Enabled This option should be enabled as part of the acceptable policy.
Network security: LAN Manager authentication level Send NTLMv2 response only Sending LM is less secure than NTLM, and should only be enabled if the system will communicate with computers running Windows 98 or Windows 95. Additionally, use NTLMv2 only; however, computers running Windows 98, Windows 95, or unpatched Windows NT4.0 will not be able to communicate with servers running NTLMv2.
Network security: LDAP client signing requirements Negotiate signing Require signing when authenticating to third party LDAP servers. This prevents attacks against rogue LDAP servers and clear-text submission of passwords over the network.
Network security: Minimum session security for NTLM SSP-based (including secure RPC) clients Require NTLMv2 session security The NTLM hashes contain weaknesses that attacks may exploit. When enabled, these requirements strengthen the authentication algorithms for Windows.
Network security: Minimum session security for NTLM SSP-based (including secure RPC) servers Require NTLMv2 session security The NTLM hashes contain weaknesses that attacks may exploit. When enabled, these requirements will strengthen the authentication algorithms for Windows.
Recovery console: Allow automatic administrative logon Disabled If automatic administrative logon is enabled, then a malicious user that has console access could simply restart the computer and gain administrative privileges. However, an organization may enable this feature if the computer is a physically secure server, allowing access to the system if the administrator password is forgotten.
Recovery console: Allow floppy copy and access to all drives and all folders Disabled The recovery console can be used as an attack method to gain access to SAM database files offline; therefore, this option should be enabled to prevent those files from being copied to a floppy disk.
Shutdown: Allow system to be shut down without having to log on Disabled This option is used to prevent users without valid accounts from shutting down the system, and is a good precautionary measure.
Shutdown: Clear virtual memory pagefile Disabled Clearing the memory pagefile at shutdown can help prevent offline analysis of the file, which might contain sensitive information from system memory, such as passwords. However, in situations in which the computer is physically secured, this can be enabled to reduce time required for system restarts.
System cryptography: Force strong key protection for user keys stored on the computer User is prompted when the key is first used Protecting local cryptographic secrets helps prevent privilege escalation across the network, once access to one system is obtained.
System cryptography: Use FIPS compliant algorithms for encryption, hashing, and signing Not Defined Require stronger, standard, and compliant algorithms for encryption, hashing, and signing.
System Objects: Default owner for objects created by members of the Administrators group Administrators group Administrators should only have access to the created file.
System objects: Require case insensitivity for non-Windows subsystems Disabled Require case-sensitivity for non-Windows subsystems, such as UNIX passwords.
System settings: Optional subsystems Enter POSIX here only if expressly required The POSIX execution layer has had multiple local exploits in the past, and should be disabled unless required by third-party software. It is extremely rare for POSIX to be required by commercial software packages.
System settings: Use Certificate Rules on Windows executables for Software Restriction policies Not Defined When certificate rules are created, enabling this option enforces software restriction policies that check a Certificate Revocation List (CRL) to make sure the software's certificate and signature are valid.

Wichtig

The WSUS subdirectories UpdateServicesPackages, WsusContent, and WsusTemp created as shared directories (for WSUS Administrators and the Network Service account) as part of WSUS setup. These directories can be found by default under the WSUS directory at the root of the largest partition on the WSUS server. Sharing of these directories may be disabled if you are not using local publishing.

Event log settings

Configure Event Log settings to help ensure an adequate level of activity monitoring.

Event log settings

Option Security setting Setting rationale
Maximum application log size 100489 kilobytes A large event log allows administrators to store and search for problematic and suspicious events.
Maximum security log size 100489 kilobytes A large event log allows administrators to store and search for problematic and suspicious events.
Maximum system log size 100489 kilobytes A large event log allows administrators to store and search for problematic and suspicious events.
Prevent local guests group from accessing application log Enabled Guest accounts should not be able to access sensitive information in the event log.
Prevent local guests group from accessing security log Enabled Guest accounts should not be able to access sensitive information in the event log.
Prevent local guests group from accessing system log Enabled Guest accounts should not be able to access sensitive information in the event log.
Retain application log 7 Days After a week, logs should be stored on a centralized log server.
Retain security log 7 Days After a week, logs should be stored on a centralized log server.
Retain system log 7 Days After a week, logs should be stored on a centralized log server.
Retention method for application log As Needed Overwrite audit logs as needed when log files have filled up.
Retention method for security log As Needed Overwrite audit logs as needed when log files have filled up.
Retention method for system log As Needed Overwrite audit logs as needed when log files have filled up.

System services

Enable only services that are required for WSUS.

Enabled operating system services

Option Security setting Setting rationale
Alerter Disabled The alerter service is of most use when an administrator is logged into the network and wants to be notified of events. For computers running WSUS, the service is not necessary.
Application Management Manual This service is only necessary when installing new applications to the environment with Active Directory.
Automatic Updates Automatic This service is required in order to support a fully patched operating environment.
Clipbook Disabled This service is unnecessary to the WSUS environment.
COM+ Event System Manual The COM+ event system might be used in the Web-based application.
Computer Browser Automatic The computer browser service is required on interactive workstations.
DHCP Client Automatic DHCP is necessary to have an IP address on the WSUS server.
Distributed File System Disabled DFS is used for file sharing across multiple servers, which is not needed for WSUS.
Distributed Link Tracking Client Disabled This service is appropriate only if a domain has distributed link tracking configured.
Distributed Link Tracking Server Disabled This service is appropriate only if a domain has distributed link tracking configured.
Distributed Transaction Coordinator Disabled This service is appropriate only if a domain uses distributed transactions, which are not needed for WSUS.
DNS Client Automatic DNS is necessary for IP-address-to-name resolution.
Event Log Automatic The Event Log service is important for logging events on the system and provides critical auditing information.
File Replication Disabled This service is used for file replication and synchronization, which is not necessary for WSUS.
IIS ADMIN Service Automatic This service is required for WSUS administration.
Indexing Service Manual This service is used by IIS.
Intersite Messaging Disabled This service needs to be enabled only on domain controllers.
Internet Connection Firewall/Internet Connection Sharing Manual This service is required if the local ICF firewall is being used.
IPsec Services Automatic This service is required if IPsec has been utilized.
Kerberos Key Distribution Center Disabled unless functioning as a domain controller This service is enabled by default in order to join and authenticate to Windows Server domain controllers.
License Logging Service Disabled This service is used on systems on which application licensing must be tracked.
Logical Disk Manager Automatic This service is used in logical disk management.
Logical Disk Manager Administrative Service Manual This service is used in logical disk management.
Messenger Disabled This service is only necessary if NetBIOS messaging is being used.
Net Logon Automatic This service is necessary to belong to a domain.
NetMeeting Remote Desktop Sharing Disabled NetMeeting is an application that allows collaboration over a network. It is used on interactive workstations, and should be disabled for servers as it presents a security risk.
Network Connections Manual This service allows network connections to be managed centrally.
Network DDE Disabled Network DDE is a form of interprocess communication (IPC) across networks. Because it opens network shares and allows remote access to local resources, it should be disabled unless explicitly needed.
Network DDE DSDM Disabled Network DDE is a form of interprocess communication (IPC) across networks. Because it opens network shares and allows remote access to local resources, it should be disabled unless explicitly needed.
NTLM Security Support Provider Manual The NTLM Security Support Provider is necessary to authenticate users of remote procedure call (RPC) services that use transports such as TCP and UDP.
Performance Logs and Alerts Manual This service is only necessary when logs and alerts are used.
Plug and Play Automatic Plug and Play is needed if the system uses Plug and Play hardware devices.
Print Spooler Disabled This service is necessary if the system is used for printing.
Protected Storage Automatic This service must be enabled because the IIS Admin service depends on it.
Remote Access Auto Connection Manager Disabled Enable this service only for RAS servers.
Remote Access Connection Manager Disabled Enable this service only for RAS servers.
Remote Procedure Call (RPC) Automatic This service is required for RPC communications.
Remote Procedure Call (RPC) Locator Manual This service is required for RPC communications.
Remote Registry Manual Remote Registry is a key target for attackers, viruses, and worms, and should be set to manual unless otherwise needed, where the server can enable it.
Removable Storage Manual For a dynamic server, this service is necessary.
Routing and Remote Access Disabled Enable this service only for RAS servers.
Security Accounts Manager Automatic This service should be enabled, as it manages local accounts.
Server Automatic This service should be enabled or disabled as necessary. The service supports file, print, and named-pipe sharing over the network for this computer.
Smart Card Manual Because users will not be using smart cards for two-factor logon authentication, this service is unnecessary and should be disabled or set to manual.
System Event Notification Automatic This service is needed for COM+ events.
Task Scheduler Manual This service should be enabled or disabled as necessary. The service enables a user to configure and schedule automated tasks on this computer.
TCP/IP NetBIOS Helper Automatic This service is used in Windows networking for computers running an operating system earlier than Windows Server 2003.
Telephony Disabled This service is not necessary in this environment because telephony devices are not used.
Telnet Disabled The telnet service should be disabled and its use strongly discouraged.
Terminal Services Manual Terminal services should be enabled or disabled as necessary.
Uninterruptible Power Supply Manual This service is necessary if a Uninterruptible Power Supply is used.
Windows Installer Manual Users may choose to use Windows Installer to install .msi packages on the system; therefore, this service should be set to manual.
Windows Management Instrumentation Manual WMI provides extended management capabilities.
Windows Management Instrumentation Driver Extensions Manual WMI Driver Extensions allow monitoring of network card connection state in the taskbar.
Windows Time Automatic External time synchronization is required for Kerberos key exchange in Active Directory environments.
Workstation Automatic The workstation service is necessary for Windows networking.

TCP/IP hardening

Microsoft recommends that you harden the TCP/IP interface for WSUS servers.

TCP/IP registry key settings

Registry key Security setting Setting rationale
HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\SynAttackProtect REG_DWORD = 1 Causes TCP to adjust retransmission of SYN-ACKS.
HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\TcpMaxHalfOpen REG_DWORD = 500 Helps protect against SYN attacks.
HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\TcpMaxHalfOpenRetried REG_DWORD = 400 Helps protect against SYN attacks.
HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\EnableICMPredirect REG_DWORD = 0 Prevents the creation of expensive host routes when an ICMP redirect packet is received.
HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\DeadGWDetectDefault REG_DWORD = 1 Allows Transmission Control Protocol to detect failure of the default gateway and to adjust the IP routing table to use another default gateway.
HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\DisableIPSourceRouting REG_DWORD = 1 Disables IP source routing.
HKLM\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\IPEnableRouter REG_DWORD = 0 Disables forwarding of packets between network interfaces.

IIS security configuration

Consider enabling the following three security settings on the IIS Web server to help ensure secure WSUS administration.

Enable general IIS error messages

By default, IIS gives detailed error messages to remote Web clients. We recommend enabling IIS general, less-detailed error messages. This prevents an unauthorized user from probing the IIS environment with IIS error messages.

To enable general IIS error messages

  1. On the Start menu, point to Programs, point to Administrator Tools, and then click Internet Information Services Manager.

  2. Expand the local computer node.

  3. Right-click Web Sites, and then click Properties.

  4. On the Home Directory tab, click Configuration.

  5. On the Debugging tab, under Error messages for script errors, click Send the following text error message to client, where the error message reads "An error occurred on the server when processing the URL. Please contact the system administrator."

Enable additional IIS logging options

By default, IIS enables logging for a number of options. However, we recommend logging several additional key options.

To enable additional IIS logging options

  1. On the Start menu, point to Programs, point to Administrator Tools, and then click Internet Information Services Manager.

  2. Expand the local computer node.

  3. Right-click Web Sites, and then click Properties.

  4. On the Web Site tab, under the Active log format box, click Properties.

  5. In Logging Properties go to the Advanced tab, and select the check boxes for the following logging options:

    • Server Name
    • Time taken
    • Host
    • Cookie
    • Referer

Remove header extensions

By default, IIS enables header extensions for HTTP requests. We recommend removing any header extensions for IIS.

To remove header extensions for HTTP requests

  1. On the Start menu, point to Programs, point to Administrator Tools, and then click Internet Information Services Manager.

  2. Expand the local computer node.

  3. Right-click Web Sites, and then click Properties.

  4. On the HTTP Headers tab, select the X-Powered-By: ASP.NET check box, and then click Remove.

SQL Server

The following are security recommendations for SQL Server with WSUS.

SQL registry permissions

Use access control permissions to secure the SQL Server registry keys.

HKLM\SOFTWARE\MICROSOFT\MSSQLSERVER

ISEC setting Rationale
Administrators: Full Control

SQL Service Account: Full Control

System: Full Control
These settings help ensure limited access to the application’s registry key to authorized administrators or system accounts.

Stored procedures

Remove all stored procedures that are unnecessary and that have the ability to control the database server remotely.

Unnecessary SQL Server 2005 stored procedures

Description Stored procedures Rationale
Delete stored procedures by using the following command:

use master exec sp_dropextendedproc stored procedure

where stored procedure is the name of the stored procedure to be deleted.
  • Sp_OACreate

  • Sp_OADestroy

  • Sp_OAGetErrorInfo

  • Sp_OAGetProperty

  • Sp_OAMethod

  • Sp_OASetProperty

  • SP_OAStop

  • Xp_regaddmultistring

  • Xp_regdeletekey

  • Xp_regdeletevalue

  • Xp_regenumvalues

  • Xp_regread

  • Xp_regremovemultistring

  • Xp_regwrite

  • sp_sdidebug

  • xp_availablemedia

  • xp_cmdshell

  • xp_deletemail

  • xp_dirtree

  • xp_dropwebtask

  • xp_dsninfo

  • xp_enumdsn

Remove all stored procedures that are not necessary for WSUS and could possibly give unauthorized users the ability to perform command-line actions on the database.
  • xp_enumerrorlogs

  • xp_enumgroups

  • xp_eventlog

  • xp_findnextmsg

  • xp_fixeddrives

  • xp_getfiledetails

  • xp_getnetname

  • xp_logevent

  • xp_loginconfig

  • xp_makewebtask

  • xp_msver

  • xp_readerrorlog

  • xp_readmail

  • xp_runwebtask

  • xp_sendmail

  • xp_sprintf

  • xp_sscanf

  • xp_startmail

  • xp_stopmail

  • xp_subdirs

  • xp_unc_to_drive