Microsoft Internet Information Server (IIS) uses a centralized repository known as the metabase to store configuration information for the Web server. In earlier versions of IIS, the metabase was stored as a single binary file readable only by specialized applications. IIS 6.0 introduces an easily readable XML version of the metabase. With this increased transparency, it's even more important that you configure metabase security options properly to ensure the confidentiality, integrity and availability of your IIS servers.
One of the most critical metabase security measures you can take is to protect the metabase configuration files using appropriate access control lists. There are four specific files that you need to protect in IIS 6.0:
- Metabase configuration information (systemrootSystem32InetsrvMetaBase.xml)
- Metabase schema file (systemrootSystem32InetsrvMBSchema.xml)
- Metabase history files (systemrootSystem32InetsrvHistory*)
- Metabase backup files (systemrootSystem32InetsrvMetaBack*)
Permissions on these files should be restricted to two entities. The NT AUTHORITYSYSTEM internal account and the BUILTINAdministrators group should have Full Control of these files/directories. All other ACL entries should be removed. If you're using an older version of IIS, you'll want to implement similar access controls for the metabase.bin binary file.
If you'd like further information on securing the IIS Metabase, you might want to consult Microsoft's Metabase Security Checklist for IIS 6.0. This checklist offers a wealth of practical advice on configuring security options for the IIS metabase.
About the author
Mike Chapple, CISSP, currently serves as Chief Information Officer of the Brand Institute, a Miami-based marketing consultancy. He previously worked as an information security researcher for the U.S. National Security Agency. His publishing credits include the TICSA Training Guide from Que Publishing, the CISSP Study Guide from Sybex and the upcoming SANS GSEC Prep Guide from John Wiley. He's also the About.com Guide to Databases.
