Mimecast Web Security: Installing the Mimecast Security Agent (Mac)

Document created by user.oxriBaJeN4 Employee on Sep 11, 2018Last modified by user.oxriBaJeN4 Employee on Jul 17, 2019
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This document provides instructions to deploy the Mimecast Security Agent (MSA) on roaming Mac devices, to work in conjunction with the Mimecast Web Security feature. In addition, it covers how to:

  • Validate the agent installation.
  • Test policy blocking.
  • Enable / disable the agent.
  • Uninstall the software.




Before installing the Mimecast Security Agent on Mac devices, ensure the following requirements are met:

  • The minimum supported OS version is macOS Sierra (10.12).
  • Administration privileges are available on the macOS.
  • The local DNS resources have "Exceptions" defined to enable your trusted domains and IPs to bypass the Mimecast Web Security functionality. View the Mimecast Web Security: Managing Exceptions page for further information.
    An exception for your local domain must be created if you have Active Directory or a Local DNS server. If the local domain is not included as an exception, you won't be able to access local resources such as IP Phones and Print Servers etc.
  • Mimecast Web Security policies have been configured. View the "Policy Configuration Recommendations" section below and the Mimecast Web Security: Configuring Policies page for further information.
  • Mimecast Security Agent Settings have been configured. View the Mimecast Web Security: Mimecast Security Agent Settings page for further information.
  • For proper function of the Mimecast Security Agent, ensure the managed endpoint systems are using a Network Time Provider to ensure accurate system clocks.


Browser Recommendations


We recommend the browser uses macOS Trust Store for Certificate of Authority. For a list of the available macOS trusted root certificates, see the Lists of Available Trusted Root Certificates in macOS page in the Apple Support documentation. 

The security agent software automatically installs the Mimecast SSL Certificate into macOS’s keychain. However if you aren't using the endpoint software, you'll need to install the Mimecast certificate for "Network Level Protection". 

Policy Configuration Recommendations


You'll need to ensure that Mimecast Web Security policies are defined and ready. Your current policy configuration will be used during testing to block a known collection of domains. Location based policies are never applied to an MSA protected endpoint, even if it's on a protected network.

Do not test with explicit sites, which when viewed are against your company policy. We recommend blocking with a safe site such as cnn.com during testing.

Policy type recommendations include: 

  • A Domain Filtering policy with explicit blocks and allows set.
  • A Category Filtering policy with known categories blocked and allowed. This policy should apply as follows:
    MSA AuthenticationApplies To
    User logs into the MSA or automatically discovered using Transparent User ID feature.
    • Individual Users 
    • Groups containing the User
    • Everyone
    User does not log into the MSA
    • Everyone
When a policy component is changed, if the system DNS cache and browser DNS cache are not cleared, the policy change will not take effect. Cache clearing updates can take up to 20 minutes, therefore you won't see the policy change take effect until this completes. 

Installing the Mimecast Security Agent (macOS)

During the installation process, you may be prompted and required to install additional software including Visual C++.

To install the security agent on a Mac:

  1. Log on to the Administration Console.
  2. Click on the Administration menu item. A drop down menu is displayed.
  3. Click on the Web Security | Agent Settings menu item. The Mimecast Security Agent "Installation" tab displays by default.
  4. Click on the Download for Mac button. The installer files download to your browser's download location with a file name of "Mimecast Security Agent.ZIP". When unzipped, a .PKG file is displayed with the key located in a "Mimecast Security Agent Configuration" folder.
    There can be a significant delay before the browser indicates the file download is complete.
  5. Launch the Mimecast Security Agent installer to start the setup wizard.
    The installer must be run as an administrator.
  6. Click on the Continue button.
  7. On the Destination Select tab, select the local disk for installation of the Mimecast Security Agent software.
  8. Click on the Continue button.
  9. On the Installation Type tab, select the local folder for installation of the Mimecast Security Agent software. Click on the Change Install Location button if required.
  10. Click on the Install button. 
  11. Enter your Mac administration credentials in the User Name and Password fields.
  12. Click on the Install Software button. The Installer runs the new software on the local system.
    During installation, the Mimecast Security Agent icon displays on the menu bar with an exclamation point.
  13. Once the security agent is successfully installed, its status is displayed as "Protected".
  14. Click on the Close button to exit the wizard.


Apple System ExtensionApple High Sierra OS


If you've the Apple High Sierra OS or higher, an authorization process is used when installing third-party kernel extensions (kexts) for the first time. If the security agent hasn't previously been installed on your Mac, you must authorize the installation. You can preauthorize the kext on behalf of your users via the MDM solution of choice.


If you have unmanaged Macs, the following steps must be followed:

  1. The System Extension Blocked dialog is displayed.
  2. Click on the OK button to continue.
  3. Click on the Allow button to unblock the system software.
    If you don't follow this step, the security agent runs in unprotected mode, and won't filter DNS requests. You'll also be periodically prompted to authorize the installation. See the "Prepare for Changes to Kernel Extensions in macOS High Sierra" page in the Apple help for further details.

Validating the Mimecast Security Agent Installation


Verify that the MSA has been installed correctly via the methods below. If any errors display, gather and send diagnostics data as outlined in the Mimecast Security Agent: Diagnostic Data page.


Checking the Activity Monitor


Open the Activity Monitor, filter for Mimecast and check for the following processes:

Mac Activity Monitor


Confirming the MSA is Running


MSA ProtectedTo confirm the MSA is running:

  1. Check that the MSA icon MSA Icon is displayed in the menu bar.
  2. Click on the MSA icon to display the home drop down menu. Ensure the following:
    • A green tick displays.
    • The status is ‘Protected’.


Checking the MSA Diagnostics


To check the MSA diagnostics:

  1. Click on the MSA Icon in the menu bar. The home drop down menu displays.
  2. Click on the Diagnostics | Show Live Diagnostics menu item.
  3. Ensure all the basic diagnostics checklist ticks display green.
  4. Click the Refresh button a few times and confirm that the updates display times increment as expected.


Protected DevicesViewing the Protected Device


To view the protected device:

  1. Read the Mimecast Web Security: Protected Devices page for details.
  2. Confirm the view shows an entry for the protected machine name.


Testing Policy


See Mimecast Web Security: Mimecast Security Agent Policy Testing for details


Disabling MSA


See Mimecast Web Security: Disabling / Enabling the Mimecast Security Agent for details.


Uninstalling the Security Agent


Remove MSA MacTo uninstall the security agent on macOS:

  1. Navigate to the Applications folder.
  2. Alongside the agent's interface, locate the Remove Mimecast Security Agent application.
  3. Launch the application and follow the guide to remove the software.


See Also...