In the event a secure Session Initiation Protocol (SIP) connection fails, the connection must be restricted from resorting to the unencrypted HTTP.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-70905	DTOO422	SV-85529r1_rule		Medium

Description
Prevents from HTTP being used for SIP connection in case TLS or TCP fail.

STIG	Date
Microsoft Skype for Business 2016 Security Technical Implementation Guide	2016-11-02

Details

Check Text ( C-71349r3_chk )
Verify the policy value for Computer Configuration -> Administrative Templates -> Skype for Business 2016 -> Microsoft Lync Feature Policies "Disable HTTP fallback for SIP connection" is set to "Enabled". Procedure: Use the Windows Registry Editor to navigate to the following key: HKLM\Software\Policies\Microsoft\office\16.0\lync Criteria: If the value disablehttpconnect is REG_DWORD = 1, this is not a finding.

Check Text ( C-71349r3_chk )

Verify the policy value for Computer Configuration -> Administrative Templates -> Skype for Business 2016 -> Microsoft Lync Feature Policies "Disable HTTP fallback for SIP connection" is set to "Enabled".

Procedure: Use the Windows Registry Editor to navigate to the following key:

HKLM\Software\Policies\Microsoft\office\16.0\lync

Criteria: If the value disablehttpconnect is REG_DWORD = 1, this is not a finding.

Fix Text (F-77237r1_fix)
Set the policy value for Computer Configuration -> Administrative Templates -> Skype for Business 2016 -> Microsoft Lync Feature Policies "Disable HTTP fallback for SIP connection" to "Enabled".