Better OWA Attachment Security

To set the way OWA handles Free-Docs, perform these steps:

1. Log on to your OWA server with an account that has Windows administrative privileges.
2. Open a registry editor (regedit.exe).
3. Navigate to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControl Set\Services\MSExchangeWeb\OWA.
4. Right-click HKEY_LOCAL_MACHINE\SYSTEM\CurrentControl Set\Services\MSExchangeWeb\OWA and select New, DWORD Value. Name the new value EnableFreeDocs.
5. Double-click the new value, and in the Edit DWORD Value dialog box, enter the desired value.
6. Click OK.

Controlling Access to Attachments Via Front-End Servers
Blocking certain types of attachments or documents is useful in itself, but sometimes you want to keep people from accessing attachments depending on where the person is, not just what the file type is. This concern is due to the nature of how OWA works. Outlook is typically installed on a machine in an environment in which the user is presumed to be an honest member of the company, and therefore it's reasonable to assume that the machine is under the user's control and is in a place where it's safe for the user to open sensitive attachments. OWA, however, is designed to be used from most any modern Web browser—even browsers running on machines that aren't under the user's control and aren't necessarily safe. OWA 2003 addresses this problem in a couple of ways, such as its provision for automatically ending users' sessions after an administrator-specified time period. (You can set separate times for public and trusted computers.) OWA 2003 also lets you restrict which servers users can use to access attachments to help reduce the risk that users will open sensitive attachments on untrusted machines. For example, you probably wouldn't block Microsoft Word documents for all users, but you might want to prevent OWA users from accessing Word documents from outside the corporate network. OWA 2003 offers two interlocking controls that let you do this fairly easily. . . .