Title

Outlook must be configured to force authentication when connecting to an Exchange server. (Cat II impact)

Discussion

Exchange Server supports the Kerberos authentication protocol and NTLM for authentication. The Kerberos protocol is the more secure authentication method and is supported on Windows 2000 Server and later versions. NTLM authentication is supported in pre-Windows 2000 environments. When authentication is enabled, Outlook will attempt to authenticate using the Kerberos authentication protocol, if it cannot (because no Windows 2000 or later domain controllers are available), it will authenticate using NTLM, ensuring a more secure authentication to the Exchange server.

Check Content

Verify the policy value for User Configuration -> Administrative Templates -> Microsoft Outlook 2013 -> Account Settings -> Exchange "Authentication with Exchange Server" is set to "Enabled (Kerberos/NTLM Password Authentication)". Procedure: Use the Windows Registry Editor to navigate to the following key: HKCU\Software\Policies\Microsoft\Office\15.0\outlook\security Criteria: If the value AuthenticationService is REG_DWORD = 9, this is not a finding.

Fix Text

Set the policy value for User Configuration -> Administrative Templates -> Microsoft Outlook 2013 -> Account Settings -> Exchange "Authentication with Exchange Server" to "Enabled (Kerberos/NTLM Password Authentication)".

Additional Identifiers

Rule ID: SV-54053r1_rule

Vulnerability ID: V-17734

Group Title: DTOO280 - Authentication w/Exchange Svr

Expert Comments

CCIs tied to check.

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