STIGQter: STIG Summary: Microsoft Exchange 2019 Mailbox Server Security Technical Implementation Guide Version: 2 Release: 3 Benchmark Date: 02 Jul 2025:

Exchange Message size restrictions must be controlled on Receive connectors.

DISA Rule

SV-259677r961155_rule

Vulnerability Number

V-259677

Group Title

SRG-APP-000247

Rule Version

EX19-MB-000124

Severity

CAT III

CCI(s)

• CCI-001095 - Manage 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 global maximum message receive size and, if operationally necessary, to document signoff with risk acceptance for the receive connector to have a different value, or verify that this information is documented by the organization.

Open the Exchange Management Shell and enter the following command:

Set-ReceiveConnector -Identity <'IdentityName'> -MaxMessageSize <'MaxReceiveSize'>

Note: The <IdentityName> and <MaxReceiveSize> values must be in quotes.

or

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

Repeat the procedure for each Receive connector.

Check Contents

Review the EDSP or document that contains this information.

Determine the global maximum message receive size and whether signoff with risk acceptance is documented for the Receive connector to have a different value.

Open the Exchange Management Shell and enter the following command:

Get-ReceiveConnector | Select-Object -Property Name, Identity, MaxMessageSize

Identify internet-facing connectors.

For each Receive connector, if the value of "MaxMessageSize" is not the same as the global value, this is a finding.

or

If "MaxMessageSize" is set to a numeric value different from the global value and has signoff and risk acceptance in the EDSP, this is not a finding.

Vulnerability Number

V-259677

Documentable

False

Rule Version

EX19-MB-000124

Severity Override Guidance

Review the EDSP or document that contains this information.

Determine the global maximum message receive size and whether signoff with risk acceptance is documented for the Receive connector to have a different value.

Open the Exchange Management Shell and enter the following command:

Get-ReceiveConnector | Select-Object -Property Name, Identity, MaxMessageSize

Identify internet-facing connectors.

For each Receive connector, if the value of "MaxMessageSize" is not the same as the global value, this is a finding.

or

If "MaxMessageSize" is set to a numeric value different from the global value and has signoff and risk acceptance in the EDSP, this is not a finding.

Check Content Reference

M

Target Key

5580