Internet Receive Connector connections count must be unlimited.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-33563	Exch-2-708	SV-43983r1_rule	ECSC-1	Low

Description
Email system availability depends in part on best practices strategies for setting tuning configurations. This configuration controls the maximum number of simultaneous inbound connections allowed to the SMTP server. By default, the number of simultaneous inbound connections is unlimited. If a limit is set and is too low, the connections pool may get filled. If attackers perceive there is a limit, they could deny service to the Simple Mail Transfer Protocol (SMTP) server by using a connection count that exceeds the limit set. By setting to unlimited, attackers would need many more connections to cause denial of service.

Description

Email system availability depends in part on best practices strategies for setting tuning configurations. This configuration controls the maximum number of simultaneous inbound connections allowed to the SMTP server. By default, the number of simultaneous inbound connections is unlimited. If a limit is set and is too low, the connections pool may get filled. If attackers perceive there is a limit, they could deny service to the Simple Mail Transfer Protocol (SMTP) server by using a connection count that exceeds the limit set. By setting to unlimited, attackers would need many more connections to cause denial of service.

STIG	Date
Exchange 2010 Edge Transport Server STIG	2013-01-03

Details

Check Text ( C-41669r1_chk )
Obtain the Email Domain Security Plan (EDSP) and locate the 'Maximum Inbound connections' value. Open the Exchange Management Shell and enter the following command: Get-ReceiveConnector \| Select Name, Identity, MaxInboundConnection Identify Internet-facing connectors on the Edge Transport server. If the value of 'MaxInboundConnection' is set to ‘unlimited’, this is not a finding. If 'MaxInboundConnection' is set to a numeric value, and has signoff and risk acceptance in the EDSP, this is not a finding.

Check Text ( C-41669r1_chk )

Obtain the Email Domain Security Plan (EDSP) and locate the 'Maximum Inbound connections' value.

Open the Exchange Management Shell and enter the following command:

Get-ReceiveConnector | Select Name, Identity, MaxInboundConnection

Identify Internet-facing connectors on the Edge Transport server.

If the value of 'MaxInboundConnection' is set to ‘unlimited’, this is not a finding.

If 'MaxInboundConnection' is set to a numeric value, and has signoff and risk acceptance in the EDSP, this is not a finding.

Fix Text (F-37455r1_fix)
Noting the Internet-facing receive connector name, open the Exchange Management Shell and enter the following command: Set-ReceiveConnector -Identity <'ReceiveConnector'> -MaxInboundConnection unlimited If an alternate value is desired, obtain signoff with risk acceptance and document in the EDSP.