Tutorial: Block download of sensitive information with Conditional Access App Control

Note

Microsoft Defender for Cloud Apps is now part of Microsoft 365 Defender, which correlates signals from across the Microsoft Defender suite and provides incident-level detection, investigation, and powerful response capabilities. For more information, see Microsoft Defender for Cloud Apps in Microsoft 365 Defender.

Today's IT admin is stuck between a rock and hard place. You want to enable your employees to be productive. That means allowing employees to access apps so they can work at any time, from any device. However, you want to protect the company's assets including proprietary and privileged information. How can you enable employees to access your cloud apps while protecting your data? This tutorial allows you to block downloads by users who have access to your sensitive data in enterprise cloud apps from either unmanaged devices or off-corporate network locations.

In this tutorial, you'll learn how to:

The threat

An account manager in your organization wants to check something in Salesforce from home over the weekend, on their personal laptop. The Salesforce data might include client credit card information or personal information. The home PC is unmanaged. If they download documents from Salesforce onto the PC, it might be infected with malware. Should the device be lost or stolen, it may not be password protected and anyone who finds it has access to sensitive information.

The solution

Protect your organization by monitoring and controlling cloud app use with any IdP solution and the Defender for Cloud Apps Conditional Access App Control.

Prerequisites

  • A valid license for Azure AD Premium P1 license, or the license required by your identity provider (IdP) solution

  • Configure a cloud app for SSO using one of the following authentication protocols:

    IdP Protocols
    Azure AD SAML 2.0 or OpenID Connect
    Other SAML 2.0
  • Make sure the app is deployed to Defender for Cloud Apps

Create a block download policy for unmanaged devices

Defender for Cloud Apps session policies allow you to restrict a session based on device state. To accomplish control of a session using its device as a condition, create both a conditional access policy AND a session policy.

To create the conditional access policy, follow the steps in Create a Defender for Cloud Apps access policy. This tutorial will explain how to create the session policy.

Step 1: Configure your IdP to work with Defender for Cloud Apps

Make sure you've configured your IdP solution to work with Defender for Cloud Apps, as follows:

After completing this task, go to the Defender for Cloud Apps portal and create a session policy to monitor and control file downloads in the session.

Step 2: Create a session policy

  1. In the Microsoft 365 Defender portal, under Cloud Apps, go to Policies, then select Policy management.

  2. In the Policies page, select Create policy followed by Session policy.

  3. In the Create session policy page, give your policy a name and description. For example, Block downloads from Salesforce for unmanaged devices.

  4. Assign a Policy severity and Category.

  5. For the Session control type, select Control file download (with inspection). This setting gives you the ability to monitor everything your users do within a Salesforce session and gives you control to block and protect downloads in real time.

  6. Under Activity source in the Activities matching all of the following section, select the filters:

    • Device tag: Select Does not equal. and then select Intune compliant, Hybrid Azure AD joined, or Valid client certificate. Your selection depends on the method used in your organization for identifying managed devices.

    • App: Select the app you want to control.

    • Users: Select the users you want to monitor.

  7. Alternatively, you can block the downloads for locations that aren't part of your corporate network. Under Activity source in the Activities matching all of the following section, set the following filters:

    • IP address or Location: You can use either of these two parameters to identify non-corporate or unknown locations, from which a user might be trying to access sensitive data.

    Note

    If you want to block downloads from BOTH unmanaged devices and non-corporate locations, you have to create two session policies. One policy sets the Activity source using the location. The other policy sets the Activity source to unmanaged devices.

    • App: Select the app you want to control.

    • Users: Select the users you want to monitor.

  8. Under Activity source in the Files matching all of the following section, set the following filters:

    • Sensitivity labels: If you use sensitivity labels from Microsoft Purview Information Protection, filter the files based on a specific Microsoft Purview Information Protection sensitivity label.

    • Select File name or File type to apply restrictions based on file name or type.

  9. Enable Content inspection to enable the internal DLP to scan your files for sensitive content.

  10. Under Actions, select block. Customize the blocking message that your users get when they're unable to download files.

  11. Set the alerts you want to receive when the policy is matched. You can set a limit so that you don't receive too many alerts. Select if to get the alerts as an email message.

  12. Select Create.

Validate your policy

  1. To simulate the blocked file download, from an unmanaged device or a non-corporate network location, sign in to the app. Then, try to download a file.

  2. The file should be blocked and you should receive the message you set under Customize block messages.

  3. In the Microsoft 365 Defender portal, under Cloud Apps, go to Policies, then select Policy management. Then select the policy you've created to view the policy report. A session policy match should appear shortly.

  4. In the policy report, you can see which logins were redirected to Microsoft Defender for Cloud Apps for session control, and which files were downloaded or blocked from the monitored sessions.

Next steps

If you run into any problems, we're here to help. To get assistance or support for your product issue, please open a support ticket.