Exchange Outlook Anywhere (OA) clients must use NTLM authentication to access email.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-207327	EX13-MB-000305	SV-207327r615936_rule		Medium

Description

Identification and authentication provide the foundation for access control. Access to email services applications require NTLM authentication. Outlook Anywhere, if authorized for use by the site, must use NTLM authentication when accessing email. Note: There is a technical restriction in Exchange OA that requires a direct SSL connection from Outlook to the CA server. There is also a constraint where Microsoft supports that the CA server must participate in the AD domain inside the enclave. For this reason, Outlook Anywhere must be deployed only for enclave-sourced Outlook users.

STIG	Date
Microsoft Exchange 2013 Mailbox Server Security Technical Implementation Guide	2021-12-16

Details

Check Text ( C-7585r393494_chk )
Open the Exchange Management Shell and enter the following command: Get-OutlookAnywhere Get-OutlookAnywhere | Select Name, Identity, InternalClientAuthenticationMethod, ExternalClientAuthenticationMethod If the value of InternalClientAuthenticationMethod and the value of ExternalClientAuthenticationMethod is not set to NTLM, this is a finding.

Fix Text (F-7585r393495_fix)
Open the Exchange Management Shell and enter the following command: For InternalClientAuthenticationMethod: Set-OutlookAnywhere -Identity ' -InternalClientAuthenticationMethod NTLM For ExternalClientAuthenticationMethod: Set-OutlookAnywhere -Identity ' -ExternalClientAuthenticationMethod NTLM