STIGQter: STIG Summary: Microsoft Exchange 2016 Mailbox Server Security Technical Implementation Guide Version: 2 Release: 3 Benchmark Date: 23 Apr 2021:

The Exchange Outbound Connection Limit per Domain Count must be controlled.

DISA Rule

SV-228389r612748_rule

Vulnerability Number

V-228389

Group Title

SRG-APP-000247

Rule Version

EX16-MB-000450

Severity

CAT III

CCI(s)

• CCI-001095 - The information system manages excess capacity, bandwidth, or other redundancy to limit the effects of information flooding types of denial of service attacks.

Weight

10

Fix Recommendation

Update the EDSP to specify the "MaxPerDomainOutboundConnection" value or verify that this information is documented by the organization.

Open the Exchange Management Shell and enter the following command:

Set-TransportService -Identity <'IdentityName'> -MaxPerDomainOutboundConnections 20

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

or

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

Check Contents

Review the Email Domain Security Plan (EDSP) or document that contains this information.

Determine the value for Maximum Outbound Domain Connections.

Open the Exchange Management Shell and enter the following command:

Get-TransportService | Select Name, Identity, MaxPerDomainOutboundConnections

If the value of "MaxPerDomainOutboundConnections" is not set to "20", this is a finding.

or

If "MaxPerDomainOutboundConnections" is set to a value other than "20" and has signoff and risk acceptance in the EDSP, this is not a finding.

Vulnerability Number

V-228389

Documentable

False

Rule Version

EX16-MB-000450

Severity Override Guidance

Review the Email Domain Security Plan (EDSP) or document that contains this information.

Determine the value for Maximum Outbound Domain Connections.

Open the Exchange Management Shell and enter the following command:

Get-TransportService | Select Name, Identity, MaxPerDomainOutboundConnections

If the value of "MaxPerDomainOutboundConnections" is not set to "20", this is a finding.

or

If "MaxPerDomainOutboundConnections" is set to a value other than "20" and has signoff and risk acceptance in the EDSP, this is not a finding.

Check Content Reference

M

Target Key

4223

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