User name and password must be disabled in all Office programs.

The Uniform Resource Locator (URL) standard allows user authentication to be included in URL strings in the form http://username:password@example.com. A malicious user might use this URL syntax to create a hyperlink that appears to open a legitimate website but actually opens a deceptive (spoofed) website. For example, the URL http://www.wingtiptoys.com@example.com appears to open http://www.wingtiptoys.com but actually opens http://example.com. To protect users from such attacks, Internet Explorer usually blocks any URLs using this syntax.