Exchange must use encryption for Outlook Web App (OWA) access.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-228416	EX16-MB-002910	SV-228416r684257_rule		Medium

Description
This setting controls whether client machines should be forced to use secure channels to communicate with this virtual directory. If this feature is enabled, clients will only be able to communicate with the directory if they are capable of supporting secure communication with the server. The use of secure communication prevents eavesdroppers from reading or modifying communications between servers and clients. The network and DMZ STIG identify criteria for OWA and Public Folder configuration in the network, including Common Access Card (CAC)-enabled pre-authentication through an application firewall proxy. Failure to require secure connections on a website increases the potential for unintended eavesdropping or data loss.

Description

This setting controls whether client machines should be forced to use secure channels to communicate with this virtual directory. If this feature is enabled, clients will only be able to communicate with the directory if they are capable of supporting secure communication with the server. The use of secure communication prevents eavesdroppers from reading or modifying communications between servers and clients. The network and DMZ STIG identify criteria for OWA and Public Folder configuration in the network, including Common Access Card (CAC)-enabled pre-authentication through an application firewall proxy. Failure to require secure connections on a website increases the potential for unintended eavesdropping or data loss.

STIG	Date
Microsoft Exchange 2016 Mailbox Server Security Technical Implementation Guide	2021-03-25

Details

Check Text ( C-30649r684256_chk )
Open a Exchange Management Shell and enter the following command: Get-OwaVirtualDirectory \| select internalurl, externalurl If the value returned is not https://, this is a finding.

Fix Text (F-30634r497045_fix)
Configure the OWA site to require SSL port 443.