Transport rules

This section describes the configuration of remote connectors within Exchange Online associated with systems built according to guidance in ASD's Blueprint for Secure Cloud.

Estimated reading time: 2 minutes

Instruction

The below tables outline the as built configuration for ASD’s Blueprint for Secure Cloud (the Blueprint) for the Microsoft Exchange admin portal at the following URL:

https://admin.exchange.microsoft.com/#/transportrules

The settings described on these pages provide a baseline implementation for a system configured using the Blueprint. Any implementation implied by these pages should not be considered as prescriptive as to how an organisation must scope, build, document, or assess a system.

Implementation of the guidance provided by the Blueprint will differ depending on an organisation’s operating context and organisational culture. Organisations should implement the Blueprint in alignment with their existing change management, business processes and frameworks.

Placeholders such as <ORGANISATION.GOV.AU>, <BLUEPRINT.GOV.AU> and <TENANT-NAME> should be replaced with the relevant details as required.

Rule conditions

Item	Value
Name	Require TLS for sensitive items
Apply this rule if
- The recipient	is external/internal
- The recipient is located	Outside the organisation
And
- The message headers…	includes any of these words
- Header Name	msip_labels
- Words or phrases	All OFFICIAL Sensitive GUIDs All PROTECTED GUIDs
Do the following
- Modify the message security	Require TLS encryption

Rule settings

Item	Value
Priority	0
Rule mode	Enforce
Severity
Match sender address in message	Header

Note

To obtain a list of all sensitivity label GUIDs for the above rule, organisations can use the Security & Compliance PowerShell. The following command will publish the label name and its associated GUID.

Get-label | Select displayname,guid

Security & Governance

None identified

Design

Configuration

None identified

References

Security & Compliance PowerShell