EX19-ED-000119 The Exchange internet receive connector connections count must be set to default.

Information

Email system availability depends in part on best practice 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 5000. If a limit is set too low, the connections pool may be filled. If attackers perceive the limit is too low, they could deny service to the Simple Mail Transfer Protocol (SMTP) server by using a connection count that exceeds the limit set. By setting the default configuration to 5000, attackers would need many more connections to cause denial of service.

Solution

Update the EDSP to reflect the Maximum Inbound connections value.

Open the Exchange Management Shell and enter the following command:

Set-ReceiveConnector -Identity <'IdentityName'> -MaxInboundConnection 5000

Note: The <IdentityName> value must be in quotes.

or

The value as identified by the EDSP that has obtained a signoff with risk acceptance.

Repeat the procedure for each receive connector.

See Also

https://dl.dod.cyber.mil/wp-content/uploads/stigs/zip/U_MS_Exchange_2019_Y24M07_STIG.zip

Item Details

Category: SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|SC-5(2), CAT|II, CCI|CCI-001095, Rule-ID|SV-259606r961155_rule, STIG-ID|EX19-ED-000119, Vuln-ID|V-259606

Plugin: Windows

Control ID: 9622521a1a7fdeb92360ef6df86b0b5d0a5a75d80ae53c9b2518537efed89add