Duo Protection for Dropbox with Duo Access Gateway

Overview

As business applications move from on-premises to cloud hosted solutions, users experience password fatigue due to disparate logons for different applications. Single sign-on (SSO) technologies seek to unify identities across systems and reduce the number of different credentials a user has to remember or input to gain access to resources.

While SSO is convenient for users, it presents new security challenges. If a user's primary password is compromised, attackers may be able to gain access to multiple resources. In addition, as sensitive information makes its way to cloud-hosted services it is even more important to secure access by implementing two-factor authentication and zero-trust policies.

Duo Access Gateway

Duo Access Gateway (DAG), our on-premises SSO product, layers Duo's strong authentication and flexible policy engine on top of Dropbox logins using the Security Assertion Markup Language (SAML) 2.0 authentication standard. Duo Access Gateway acts as an identity provider (IdP), authenticating your users using existing on-premises or cloud-based directory credentials and prompting for two-factor authentication before permitting access to Dropbox.

Duo Access Gateway is included in the Duo Premier, Duo Advantage, and Duo Essentials plans, which also include the ability to define policies that enforce unique controls for each individual SSO application. For example, you can require that Salesforce users complete two-factor authentication at every login, but only once every seven days when accessing Dropbox. Duo checks the user, device, and network against an application's policy before allowing access to the application.

Deploy or Update Duo Access Gateway

1. Install Duo Access Gateway on a server in your DMZ. Follow our instructions for deploying the server, configuring DAG settings, and adding your primary authentication source.

2. Add the attributes from the table below that correspond to the Duo attributes Mail attribute and Username attribute in the "Attributes" field when configuring your Active Directory or OpenLDAP authentication source in the DAG admin console, separated by a comma. For example, if Active Directory is your authentication source, enter mail,sAMAccountName in the "Attributes" field.

   Duo Attribute	Active Directory	OpenLDAP
   Mail attribute	mail	mail
   Username attribute	sAMAccountName	uid

   If your organization uses other directory attributes than the ones listed here then enter those attribute names instead. If you've already configured the attributes list for another cloud service provider, append the additional attributes not already present to the list, separated by a comma.

3. After completing the initial DAG configuration steps, click Applications on the left side of the Duo Access Gateway admin console.

4. Scroll down the Applications page to the Metadata section. This is the information you need to provide to Dropbox when configuring SSO. Click the Download Certificate link to obtain the token signing certificate (the downloaded file is named "dag.crt").

   

Enable Dropbox SSO

Add the Duo Access Gateway as a new single sign-on provider for Dropbox.

1. Log on to the Dropbox admin console and navigate to Authentication → Single sign-on.

2. Check the Enable single sign-on box.

3. Select if you will make single sign-on for your Dropbox users Optional or Required.

4. Copy the SSO URL information from the Duo Access Gateway admin console Metadata display and paste it into the Dropbox Sign in URL field.

   Example: https://yourserver.example.com/dag/saml2/idp/SSOService.php

5. The "X.509 certificate" is the DAG Metadata certificate supplied by Duo Access Gateway. Click Change certificate to select the dag.crt file you downloaded from the DAG admin console "Application" page earlier.

6. After you've entered all the required information click Save Changes.

   

Learn more about Dropbox SSO at the Dropbox Help Center.

Create the Dropbox Application in Duo

1. Log on to the Duo Admin Panel and navigate to Applications → Protect an Application.

2. Locate the entry for Dropbox with a protection type of "2FA with SSO self-hosted (Duo Access Gateway)" in the applications list. Click Protect to the far-right to start configuring Dropbox. See Protecting Applications for more information about protecting applications with Duo and additional application options.

3. Dropbox uses the Mail attribute when authenticating. We've mapped Mail attribute to DAG supported authentication source attributes as follows:

   Duo Attribute	Active Directory	OpenLDAP	SAML IdP	Google	Azure
   Mail attribute	mail	mail	mail	email	mail

   If you are using a non-standard email attribute for your authentication source, check the Custom attributes box and enter the name of the attribute you wish to use instead.

4. Click Save Configuration to generate a downloadable configuration file.

   

5. You can adjust additional settings for your new SAML application at this time — like changing the application's name from the default value, enabling self-service, or assigning a group policy — or come back and change the application's policies and settings after you finish SSO setup. If you do update any settings, click the Save button when done.

6. Click the Download your configuration file link to obtain the Dropbox application settings (as a JSON file).

   Important: This file contains information that uniquely identifies this application to Duo. Secure this file as you would any other sensitive or password information. Don't share it with unauthorized individuals or email it to anyone under any circumstances!

Add the Dropbox Application to Duo Access Gateway

Before you do this, verify that you updated the "Attributes" list for your Duo Access Gateway authentication source as specified here.

1. Return to the Applications page of the DAG admin console session.

2. Click the Choose File button in the "Add Application" section of the page and locate the Dropbox SAML application JSON file you downloaded from the Duo Admin Panel earlier. Click the Upload button after selecting the JSON configuration file.

3. The Dropbox SAML application is added.

   

Verify SSO

You can log on to Dropbox by entering your e-mail address from their website and click Log in. This redirects to the Duo Access Gateway login page. Enter your primary directory logon information, approve Duo two-factor authentication, and get redirected back to the Dropbox site after authenticating.

If using the Dropbox desktop or mobile app, enter your federated e-mail address then authenticate to Duo Access Gateway.

Congratulations! Your Dropbox users now authenticate using Duo Access Gateway.

Microsoft AD FS

Microsoft's Active Directory Federation Services (AD FS) is a popular choice for SSO because it easily integrates with the AD identity store many organizations already have deployed. Duo's support for cloud applications and SSO drops in to an existing AD FS installation to provide secondary authentication after a user passes primary authentication (successful Active Directory logon).

If you don't already have AD federation running the first step is to install and configure Microsoft AD FS in your organization. Deployment Guides for AD FS versions 2.1, and 3.0/4.0 are available from Microsoft.

Once your AD FS services are up and running, the second step is to configure the SSO partnership between your AD FS service and the external cloud resource, in this case Dropbox. Learn more about configuring Dropbox SSO with AD FS at the Dropbox Help Center.

After you have successfully configured and tested AD FS SSO login to Dropbox using your AD domain credentials, you can then install the Duo AD FS integration. AD FS protection is included with Duo Essentials, Duo Advantage, and Duo Premier plans.

With the Duo integration for AD FS installed, users pass primary authentication to the AD FS service as usual. Once primary authentication succeeds, users are forwarded to the Duo service for secondary authentication. After approving logon using one of Duo's authentication methods, the user is fully logged in to Dropbox.

Other Identity Partners

Using a third-party SSO provider for cloud application access? Duo partners with leading cloud SSO providers like Okta and OneLogin to secure access with our strong and flexible authentication platform.

You can also use Duo two-factor authentication with CAS and Shibboleth on-premises IdPs.

Troubleshooting

Need some help? Try searching our Knowledge Base articles or Community discussions. For further assistance, contact Support.