STIGQter: STIG Summary: Microsoft Exchange 2019 Mailbox Server Security Technical Implementation Guide Version: 2 Release: 3 Benchmark Date: 02 Jul 2025:

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

DISA Rule

SV-259703r961494_rule

Vulnerability Number

V-259703

Group Title

SRG-APP-000391

Rule Version

EX19-MB-000203

Severity

CAT II

CCI(s)

• CCI-001953 - Accepts Personal Identity Verification-compliant credentials.

Weight

10

Fix Recommendation

Open the Exchange Management Shell and enter the following command:

For InternalClientAuthenticationMethod:

Set-OutlookAnywhere -Identity '<IdentityName'> -InternalClientAuthenticationMethod NTLM

For ExternalClientAuthenticationMethod:

Set-OutlookAnywhere -Identity '<IdentityName'> -ExternalClientAuthenticationMethod NTLM

Check Contents

Open the Exchange Management Shell and enter the following command:

Get-OutlookAnywhere

Get-OutlookAnywhere | Select-Object -Property Name, Identity, InternalClientAuthenticationMethod, ExternalClientAuthenticationMethod

If the value of "InternalClientAuthenticationMethod" and the value of "ExternalClientAuthenticationMethod" are not set to NTLM, this is a finding.

Vulnerability Number

V-259703

Documentable

False

Rule Version

EX19-MB-000203

Severity Override Guidance

Open the Exchange Management Shell and enter the following command:

Get-OutlookAnywhere

Get-OutlookAnywhere | Select-Object -Property Name, Identity, InternalClientAuthenticationMethod, ExternalClientAuthenticationMethod

If the value of "InternalClientAuthenticationMethod" and the value of "ExternalClientAuthenticationMethod" are not set to NTLM, this is a finding.

Check Content Reference

M

Target Key

5580