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McAfee Employee jebeling
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Implementing Tenant Restrictions for Microsoft Office 365

SSL connections to Azure AD can be decrypted by McAfee Web Gateway and headers can be inserted and replaced providing full support for Tenant Restrictions as defined here: Manage access to cloud apps by restricting tenants - Azure | Microsoft Docs

 

Reading the entire Microsoft article is recommended but here are the highlights as it pertains to implementing on MWG:

 

In order to implement what is described in the Microsoft article. You need to have an Azure AD account (comes with Office 365) and you need a proxy like McAfee Web Gateway or McAfee Web Gateway cloud service that performs SSL decryption and can modify headers when accessing the following hosts.

 

login.microsoftonline.com

login.microsoft.com

login.windows.net

 

The Certificate Authority used by the web gateway or cloud service must be trusted by the application or browser being used to access cloud services.

 

Note: At the time of this writing you would need to use a McAfee Web Gateway to manage policy on McAfee Web Gateway Cloud Service in order to implement this feature when filtering through the McAfee cloud (For example if you wanted to enforce tenant restrictions when using the cloud service through an IPSec tunnel or when using the cloud service via explicit proxy using MCP or IP Authentication).

 

The two headers that must be added or replaced are:

 

Restrict-Access-To-Tenants

Restrict-Access-Context

 

You will need to know your Azure AD Tenant ID and obviously the domains that you want to restrict access to. An MWG ruleset from 7.7.2 is attached, all features and properties used in the ruleset are available on all supported versions of McAfee Web Gateway. To use the ruleset you will need to import it and modify the parameters to include your domains and Azure AD ID.

 

Rule Sets
Azure AD Tenant Restrictions
[✔] Enabled [✘] Disabled in Cloud
Applies to: [✔] Requests [✔] Responses [✔] Embedded Objects
1: URL.Host is in list Azure AD
Enabled Rule Action Events Comments
[✔] Enabled Delete Restrict Access To Tenants Header
1: Header.Exists("Restrict-Access-To Tenants") equals true
Continue Header.RemoveAll("Restrict-Access-To-Tenants")  
[✔] Enabled Write Restrict Access to Tenants Header
Always
Continue Header.Add("Restrict-Access-To-Tenants","Add domain names here")  
[✔] Enabled Delete Restrict Access Context Header
1: Header.Exists("Restrict-Access-Context") equals true
Continue Header.RemoveAll("Restrict-Access-Context")  
[✔] Enabled Write Restrict Access to Tenants Header
Always
Continue Header.Add("Restrict-Access-Context","Add Azure AD ID here")  

 

Lists
String
# Azure AD  
  String Comment
1 login.microsoftonline.com  
2 login.microsoft.com  
3 login.windows.net  

 

Note, if you are going to use this in conjunction with the Bypass Office365 Services ruleset, then you would need to add a criteria/condition to that RuleSet to exclude these three Microsoft Login URLs as they are embedded in the following lists and thus hit the Stop Cycle action.

 

Lync Online URLs

Office 365 URLs

Office for iPad URLs

Office Mobile URLs

SharePoint Online URLs

 

 

Rule Sets
Bypass Microsoft (Office 365) Services

[This rule set contains rules to bypass Office 365 and/or other Microsoft services.]

[✔] Enabled [✔] Enabled in Cloud
Applies to: [✔] Requests [✔] Responses [✘] Embedded Objects
1: URL.Host is not in list Azure AD
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kbjja
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Message 2 of 5

Re: Implementing Tenant Restrictions for Microsoft Office 365

When I enable tenant restrictions the login page will no longer load. Where in the request cycle should this be placed? It seems like any modification to the header causes a problem for the microsoft site.

kbjja
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Message 3 of 5

Re: Implementing Tenant Restrictions for Microsoft Office 365

I usechrome it appears I am getting an Error 400, 'Invalid Header' error. I'm using the importable rule.

McAfee Employee jebeling
McAfee Employee
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Message 4 of 5

Re: Implementing Tenant Restrictions for Microsoft Office 365

Sorry I just saw these posts. Are you decrypting SSL for the login sites? Did you perform a rule trace?

McAfee Employee jebeling
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Message 5 of 5

Re: Implementing Tenant Restrictions for Microsoft Office 365

Two additional notes:

  1. The added rules only need to apply to the request cycle even though the attached ruleset has it for all cycles.
  2. The ruleset should be placed after SSL Scanning. (SSL Scanning has to be enabled for at least the URLs specified.
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