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Circumvent SMC EAS control for Office 365

Currently SMC 7.0 EAS proxy works with "SMC Managed" devices only (Devices that it knows about); by SMC sending the appropriate PowerShell commands to Office 365 cloud to deny/allow EAS functionality on non-compliant/compliant devices accordingly.

However, the downside of this approach is that Exchange Autodiscover is set-up in DNS to point to Office 365 in the MS cloud (as this is where the users mailbox now exists) and not the SMC server on the customer premise / managed Sophos cloud.

The end result is that if a user wants to set-up their mobile device and connect to Office 365 without the intervention and control of SMC, then they can do this very easily. - They just set-up a new mail account, adding in their email address, all without having to go via SMC. 

Effectively bypassing SMC, resulting in uncontrolled access to corporate data

This is basically what our users are doing right now to circumvent the SMC controls.

Whilst one can set-up minimum EAS connectivity requirements in Office 365 directly (e.g. PIN requirement, etc.), these out of the box controls aren’t as granular and secure as a dedicated MDM/EMM solution.

The preferred approach would be to link the SMC solution to an Active Directory group of ALL Office 365 users, and pull the users email addresses from that group membership. In turn, SMC would have the required information to link these users to both SMC and Office 365, as they would have common attributes, and control devices whether they are in SMC or not.

Example 1: 
1. SMC to extract email address from AD group. Example user; Joe.bloggs@domain.com 
2. SMC to lookup that user in SMC and list their assigned and managed devices by Active Sync ID.
3. As normal, SMC would then manage EAS access on the known devices as appropriate – compliant / non-compliant 
4. *EXTRA STEP* SMC would lookup the user in Office 365 and simply deny EAS access to unmanaged devices (Devices it doesn't have listed under the control of SMC) – that is until they become both managed and compliant

 

As a side note; Office 365 sees the built-in mobile OS email client and the downloaded Outlook mobile email client as two separate devices in EAS because of a different Active Sync ID.

HOWEVER, this looks easier to implement in SMC than I originally thought...

Sophos SMC already holds the required information about unknown devices in the file 'accessLog_ProxyEAS.xml.' - Each unknown device is listed as:

<deniedMessage>unknown active sync id</deniedMessage>

So surely this is quite achievable by Sophos to stop people easily circumventing SMC!?

 I'm happy to demonstrate this to Sophos.

 

Sophos?



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  • hello im currently looking at server integration as this is now a requirement within our organisation, this is quite an interesting read, have you received any further information on this? we currently use Sophos but are looking at additional products like airwatch.

  • Hi Andrew,

    I raised a case with Sophos support and here’s what they said...

    Regarding this issue with your users accessing corporate email on unmanaged devices, this is because our EAS Proxy only makes changes to devices that are managed by SMC (as a security precaution rather than us impacting all devices in O365 that may never have anything to do with SMC or become managed). The good news is that you can change the default ActiveSync access for devices in O365 itself, if that's the behaviour you are after.

    Log into the Exchange Admin Center and go into Mobile > Mobile Device Access > Edit > Block Access. This will disable ActiveSync access for any device by default (rather than allow all by default) so that, when a device is managed and becomes compliant with SMC, we will then enable ActiveSync for that device.

    To which I replied:

    I tried the whole block thing from EAS, but the problem there is the users who use Microsoft Outlook app... EAS gives this app it’s own Active Sync ID, which Sophos considers as an unknown Active Sync ID.

    Thus the Outlook app gets blocked. As far as the user is concerned their mobile device is compliant.

    So the issue here still comes down to Active Sync ID’s.

    In Short. Sophos / EAS / and Outlook app don’t play well together.

    ———

    The case got moved to Sophos engineering, but I feel that it will fall into the dark pit.

    I also have Airwatch on my radar, and Trend for AV - there are design issues and defects with Sophos end point protection that have been crippling us for over a year and Sophos have done nothing.

    I chased but was officially told on one of my cases that not many people use Apple Macs with Sophos and the case has low priority!

    Ridiculous!

    I’ve been a Sophos customer for over 15 years, have been a case ID, have helped Sophos out on numerous occasions with UX, and as far as I’m concerned they are not the Sophos of old. (Since the buy outs they’ve lost touch with their customer base). We’re just a $ sign to them.

    Rant over.  :)

    Good luck with the EAS issue. If I get any updates beyond here I’ll post them up.

  • I see no mention of utilizing the Sophos secure email app.  The secure email app is a well thought out part of the Sophos Mobile product and should be considered in your design. It would also containerize and protect your email data. Auto deployment using device profiles makes it a fairly air tight solution.

    Would that not give you what you are looking for?

    Cheers,

    Danny

Reply
  • I see no mention of utilizing the Sophos secure email app.  The secure email app is a well thought out part of the Sophos Mobile product and should be considered in your design. It would also containerize and protect your email data. Auto deployment using device profiles makes it a fairly air tight solution.

    Would that not give you what you are looking for?

    Cheers,

    Danny

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