Access to the configuration file is required, please read guidelines here.
When a user clicks 'View this document with Google Viewer', a publicly accessibly page is created on the Intranet. For someone else to access this, they would need to 'guess' the URL, which includes an auto-generated MD5 hash, so it would be incredibly difficult to find. In addition, the public page is only stored for 2 minutes and then removed from the server.
To disable this feature, look for the following lines of code in the configuration file and change the variable value to false:
// If preview with google viewer is enabled $cfg_google_viewer_enabled = true;