| Separation of roles supports operational security for application and protocol services. The HTTP path to web sites is a proven convenience in requiring only a browser to access them, but is simultaneously a well known attack vector for people and applications that would attempt to gain unwelcome admittance.
Web-based applications such as Exchange Outlook Web App (OWA) reside on Windows domain Member Servers, and are classified as ‘internal’, or private web servers. In order for the DoD to grant web-based access to E-mail services, careful authentication, encryption, and other precautions are needed.
Authentication, via Common Access Card, is not a feature of Exchange 2003. Add to that, it is risky to admit Internet-sourced web traffic, even with SSL or TLS encryption, into the enclave without some inspection, such as for suspicious URL formations. Also, ensuring that only the desired protocols are allowed reduces risk as well as excess traffic.
An application proxy server, such as Microsoft Threat Management Gateway (TMG) server is an effective firewall and proxy that offers all of these features when properly equipped and configured. Failure to require CAC authentication of each user, a new security context for the transaction, and FIPS 140-2 compliant encryption for the Internet leg of the transaction, all increase risk of compromise to the OWA web server. |
