Exchange must use Encryption for OWA access.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-69717	EX13-CA-000010	SV-84339r1_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 CAC enabled pre-authentication through an application firewall proxy. Failure to require secure connections on a web site 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 CAC enabled pre-authentication through an application firewall proxy. Failure to require secure connections on a web site increases the potential for unintended eavesdropping or data loss.

STIG	Date
MS Exchange 2013 Client Access Server Security Technical Implementation Guide	2019-01-02

Details

Check Text ( C-70159r1_chk )
Open a Windows PowerShell and enter the following command: Import-module webadministration At the IIS: prompt, enter cd Sites At the Sites: prompt, enter cd “Default Web Site” At the “Default Web Site”: prompt, enter cd owa At the IIS:\Sites\Default Web Site\owa>: prompt, enter Get-WebConfigurationProperty -filter /system.webServer/security/access -name sslflags If the value returned is not Ssl,Ssl128, this is a finding.

Check Text ( C-70159r1_chk )

Open a Windows PowerShell and enter the following command:

Import-module webadministration

At the IIS: prompt, enter cd Sites
At the Sites: prompt, enter cd “Default Web Site”
At the “Default Web Site”: prompt, enter cd owa

At the IIS:\Sites\Default Web Site\owa>: prompt, enter Get-WebConfigurationProperty -filter /system.webServer/security/access -name sslflags

If the value returned is not Ssl,Ssl128, this is a finding.

Fix Text (F-75921r1_fix)
Configure the OWA site to require SSL port 443.