IIS 5/5.1 Security Checklist

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- J.D. Meier, Alex Mackman, Michael Dunner, Srinath Vasireddy, Ray Escamilla and Anandha Murukan


Contents

Patches and Updates

  • MBSA is run on a regular interval to check for latest operating system and components updates.
  • The latest updates and patches are applied for Windows, IIS server, and the .NET Framework. (These are tested on development servers prior to deployment on the production servers.)
  • Subscribe to the Microsoft Security Notification Service at http://www.microsoft.com/technet/security/bulletin/notify.asp.


IISLockdown

  • IISLockdown has been run on the server.
  • URLScan is installed and configured.


Services

  • Unnecessary Windows services are disabled.
  • Services are running with least-privileged accounts.
  • FTP, SMTP, and NNTP services are disabled if they are not required.
  • Telnet service is disabled.
  • ASP .NET state service is disabled and is not used by your applications.


Protocols

  • WebDAV is disabled if not used by the application OR it is secured if it is required. For more information, see Microsoft Knowledge Base article 323470, "How To: Create a Secure WebDAV Publishing Directory."
  • TCP/IP stack is hardened.
  • NetBIOS and SMB are disabled (closes ports 137, 138, 139, and 445).


Accounts

  • Unused accounts are removed from the server.
  • Windows Guest account is disabled.
  • Administrator account is renamed and has a strong password..
  • IUSR_MACHINE account is disabled if it is not used by the application.
  • If your applications require anonymous access, a custom least-privileged anonymous account is created.
  • The anonymous account does not have write access to Web content directories and cannot execute command-line tools.
  • ASP.NET process account is configured for least privilege. (This only applies if you are not using the default ASPNET account, which is a least-privileged account.)
  • Strong account and password policies are enforced for the server.
  • Remote logons are restricted. (The "Access this computer from the network" user-right is removed from the Everyone group.)
  • Accounts are not shared among administrators.
  • Null sessions (anonymous logons) are disabled.
  • Approval is required for account delegation.
  • Users and administrators do not share accounts.
  • No more than two accounts exist in the Administrators group.
  • Administrators are required to log on locally OR the remote administration solution is secure.


Files and Directories

  • Files and directories are contained on NTFS volumes.
  • Web site content is located on a non-system NTFS volume.
  • Log files are located on a non-system NTFS volume and not on the same volume where the Web site content resides.
  • The Everyone group is restricted (no access to \WINNT\system32 or Web directories).
  • Web site root directory has deny write ACE for anonymous Internet accounts.
  • Content directories have deny write ACE for anonymous Internet accounts.
  • Remote IIS administration application is removed (\WINNT\System32\Inetsrv\IISAdmin).
  • Resource kit tools, utilities, and SDKs are removed.
  • Sample applications are removed (\WINNT\Help\IISHelp, \Inetpub\IISSamples).


Shares

  • All unnecessary shares are removed (including default administration shares).
  • Access to required shares is restricted (the Everyone group does not have access).
  • Administrative shares (C$ and Admin$) are removed if they are not required (Microsoft Management Server (SMS) and Microsoft * Operations Manager (MOM) require these shares).


Ports

  • Internet-facing interfaces are restricted to port 80 (and 443 if SSL is used).
  • Intranet traffic is encrypted (for example, with SSL) or restricted if you do not have a secure data center infrastructure.


Registry

  • Remote registry access is restricted.
  • SAM is secured (HKLM\System\CurrentControlSet\Control\LSA\NoLMHash). This applies only to standalone servers.


Auditing and Logging

  • Failed logon attempts are audited.
  • IIS log files are relocated and secured.
  • Log files are configured with an appropriate size depending on the application security requirement.
  • Log files are regularly archived and analyzed.
  • Access to the Metabase.bin file is audited.
  • IIS is configured for W3C Extended log file format auditing.


Sites and Virtual Directories

  • Web sites are located on a non-system partition.
  • "Parent paths" setting is disabled.
  • Potentially dangerous virtual directories, including IISSamples, IISAdmin, IISHelp, and Scripts virtual directories, are removed.
  • MSADC virtual directory (RDS) is removed or secured.
  • Include directories do not have Read Web permission.
  • Virtual directories that allow anonymous access restrict Write and Execute Web permissions for the anonymous account.
  • There is script source access only on folders that support content authoring.
  • There is write access only on folders that support content authoring and these folder are configured for authentication (and SSL encryption, if required).
  • FrontPage Server Extensions (FPSE) are removed if not used. If they are used, they are updated and access to FPSE is restricted.


Script Mappings

  • Extensions not used by the application are mapped to 404.dll (.idq, .htw, .ida, .shtml, .shtm, .stm, idc, .htr, .printer).
  • Unnecessary ASP.NET file type extensions are mapped to "HttpForbiddenHandler" in Machine.config.


ISAPI Filters

  • Unnecessary or unused ISAPI filters are removed from the server.


IIS Metabase

  • Access to the metabase is restricted by using NTFS permissions (%systemroot%\system32\inetsrv\metabase.bin).
  • IIS banner information is restricted (IP address in content location disabled).


Server Certificates

  • Certificate date ranges are valid.
  • Certificates are used for their intended purpose (for example, the server certificate is not used for e-mail).
  • The certificate's public key is valid, all the way to a trusted root authority.
  • The certificate has not been revoked.


Machine.config

  • Protected resources are mapped to HttpForbiddenHandler.
  • Unused HttpModules are removed.
  • Tracing is disabled <trace enable="false"/>
  • Debug compiles are turned off.
  <compilation debug="false" explicit="true" defaultLanguage="vb">

Code Access Security

  • Code access security is enabled on the server.
  • All permissions have been removed from the local intranet zone.
  • All permissions have been removed from the Internet zone.


Other Check Points

  • IISLockdown tool has been run on the server.
  • HTTP requests are filtered. URLScan is installed and configured.
  • Remote administration of the server is secured and configured for encryption, low session time-outs, and account lockouts.


Dos and Don'ts

  • Do use a dedicated machine as a Web server.
  • Do physically protect the Web server machine in a secure machine room.
  • Do configure a separate anonymous user account for each application, if you host multiple Web applications,
  • Do not install the IIS server on a domain controller.
  • Do not connect an IIS Server to the Internet until it is fully hardened.
  • Do not allow anyone to locally log on to the machine except for the administrator
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