Client-Side Defense

This guide provides instructions about how to enable Client-Side Defense (CSD) and how to apply it to your web applications using F5 Distributed Cloud Console. For more information about CSD, see About Client-Side Defense.

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Prerequisites

• A valid F5 Distributed Cloud Console Account. If you do not have an account, see Getting Started with Distributed Cloud Console.

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Enable CSD

To enable CSD on Distributed Cloud Console, do the following:

1. In Common services, select the Client-Side Defense tile.

2. In the Client-Side Defense screen that appears, click Enable Client-Side Defense.

CSD is now enabled and ready for use.

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Add a domain for CSD protection

After you enable CSD on Distributed Cloud Console, add the root domain for all domains where you want to apply CSD protection:

1. In the CSD dashboard, go to Configuration.

2. Select Add domain to protect. The Domain to protect screen appears.

3. In the Domain to protect screen, enter the root domain you want to protect and select Save and Exit.

The domain you added now appears in the list of domains to protect.

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Injecting the CSD JS on your web pages

After you add the domains on which to apply CSD protection, you must inject the CSD JavaScript on the web pages in the domain. F5 recommends injecting the CSD JavaScript on all web pages in the domain to maximize CSD protection.

Note: You can also use BIG-IP to inject the CSD JavaScript in your website pages. For information, see https://techdocs.f5.com/en-us/bigip-17-1-0/big-ip-dcs-client-side-defense-implementation.html.

To inject the CSD JavaScript on web pages:

1. In the CSD dashboard, go to Configuration.

2. Select How to Inject JS. The How to Inject JS screen appears.

3. Follow the instructions for injecting the CSD JavaScript in the How to Inject JS screen.

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Verifying your email on the Alert Receiver

When you enable CSD, CSD automatically creates an Alert Receiver using the email address you entered for your account on Distributed Cloud Console. CSD also automatically creates an Alert Policy and adds a CSD alerts group to this policy. To ensure that you receive alerts when CSD detects suspicious activity, you need to verify your email on the Alert Receiver.

To verify your email on the Alert Receiver:

1. In the System namespace, in the left navigation pane, go to Manage > Alerts Management > Alert Receivers.

2. In the Alert Receivers screen, find the client-side-defense-receiver row and in its Actions column select the icon with three dots. A pop-up menu will appear.

3. Select Verify Email, and then select Send email to send the verification email.

4. After you receive the email, return to the Alert Receivers screen.

5. Find the client-side-defense-receiver row and in its Actions column select the icon with three dots. A pop-up window will appear.

6. Select Enter verification code, enter the verification from the email, and then select Verify receiver.

There is no CSD-specific alert receiver configuration. For information about how to create and configure Alert Receivers and Alert Policies, click here.

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Testing the JS injection on your web pages

After you add domains for CSD protection and inject the CSD JavaScript on your web pages, you can test if the JavaScript injection was successful on a web page. Testing for the CSD JavaScript injection is not required, but F5 recommends performing this test to verify that your web pages are recieving CSD protection.

To perform testing for the CSD JavaScript injection:

1. In the CSD dashboard, go to Configuration.

2. Find the domain in the list that contains the web page that you want to test, and select the Test JS Injection button at the end of the row on the right. The Test JS Injection screen appears.

3. In the Test JS Injection screen, paste the URL of the web page that you want to test and select Test JS Injection.

When the test is finished, the CSD dashboard displays a confirmation message indicating whether or not the CSD JavaScript was detected on the web page.

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Using the CSD dashboard

Monitoring > Dashboard

The CSD Monitoring Dashboard page displays the suspicious network interactions with additional information for deciding whether to mitigate or allow a suspicious domain. When a web page with CSD protection is loaded on the end-user’s browser, scripts running on that webpage interact with other domains. The Suspicious Domains list displays a list of the domains that those scripts interact with and which CSD detected to be potentially malicious.

Monitoring > Script List

For your reference, XC Client-Side Defense lists all discovered JavaScript scripts for a page. The list provides an overview of which scripts interact with the different webpage elements.

To view the list, in the left navigation menu go to Monitoring > Script List.

Select a script to see the following information:

• Script behaviors (new or otherwise) over time.
• All network interactions for the script.
• All form fields read by this script.

For information about script objects, see The Script Object - Detailed Information on Script Behavior.

Note that script behavior is not currently represented in the dashboard. Use the "Status" column on this page to track scripts that display suspicious behaviors. Scripts have one of the following statuses:

• NA - No Action Needed: CSD did not find anything suspicious with this script.
• Resolved - No Action Needed: CSD found some suspicious behaviors with this script that a user has already taken action on.
• AN - Action Needed: CSD found some suspicious behaviors with the script that needs your attention.

To assist in demonstrating compliance with the Payment Card Industry Data Security Standard (PCI DSS) v4.0 Requirement 6.4.3, users can add comments containing written justifications for the specific utility of each script in the script list.

To add a script justification:

1. Go to the row of the script you would like to add a justification for and in its Actions column select the icon with three dots. A pop-up menu will appear.

2. Select Add Justification

   

   Figure: Add Justification Button

3. Add a justification in the text box and select Add

   

   Figure: Justification Form Field

Monitoring > Network

The CSD Monitoring Network page displays several tabs for displaying holistic network data, which can assist you when deciding whether to mitigate or allow a suspicious domain:

• All Domains:  When a web page with CSD protection is loaded, scripts running on that web page interact with other domains. The All Domains list displays a list of the domains that those scripts interact with.

• Mitigate List:  Displays a list of domains that the user has assigned for mitigation. When a domain is assigned for mitigation, CSD blocks that domain and it cannot be accessed by any script running on the end-user's browser when accessing a CSD protected web page.

• Allow List:  Displays a list of domains that the user has decided don't need mitigation and are allowed free access.

Manage > Configuration

The CSD Manage Configuration page is for configuring your web application for CSD protection. The page displays a list of your root domains that are configured for CSD protection, and also the following:

• Add domains for CSD protection.

• Display instructions for injecting the CSD JS on web pages in a domain.

• Schedule a CSD training session.

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Viewing suspicious domains

When CSD detects suspicious activity on a domain that has been configured for CSD protection, the user is alerted and that domain is added to the dashboard.

Filtering suspicious domains by location

You can filter the Suspicious Domains list according to a specific location or locations where CSD detected suspicious activity.

To filter the Suspicious Domains list by location:

1. In the upper-right of the page, select Select Page. A pop-up list will appear.

2. Select one or more locations, and then select Apply.

The list now displays only those domains containing the locations you selected.

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Adding a domain to the Mitigate List or Allow List

To add a domain to the Mitigate List or Allow List:

1. Go to the Suspicious Domains list or All Domains list.

2. Go to the row of the relevant domain, and in its Actions column select the icon with three dots. A pop-up menu will appear.

3. Select Add to Allow List/Add to Mitigate List.

Alternatively, you can add a domain directly from the Mitigation List or Allow List as follows:

1. In the Mitigation List or Allow List, select Add domain. A new screen appears.

2. Enter the domain name and then select Save and Exit.

After adding a domain to the Mitigate List or Allow List, you can delete it from the list by selecting the icon with three dots in the Actions column, and then selecting Delete.

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Viewing domain details

From the Suspicious Domains list or All Domains list, you can view the following domain information by selecting the domain from the list:

• Reasons why this domain may be at risk
• Risk score
• Web pages on this domain with CSD protection
• Scripts that are potentially networking with the domain

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The Script Object - Detailed Information on Script Behavior

The three main components of a script object are displayed on the following tabs:

• Overview: Captures behavior of the script over time.

  It includes the following information:

  • Script Behaviors Over Time: A graphical representation of changes to the behavior of a script over time. You can configure the time frame and behaviors displayed in the chart.

    

    Figure: Script Behaviors Over Time

  • New Behaviors Pane: Lists all new behaviors of this script during the selected time interval.

  • All Behaviors Pane: Lists all behaviors of this script during the selected time interval.

• Network: Captures all network interactions of a specific script.

• Form Fields: Lists all form fields read by a specific script.

Note: To take action on the behaviors of the script, navigate to either the Network or Form Fields tab.Select either the Mitigation or Allow action. Based on the action you select, the status of the script changes to reflect whether the suspicious behavior is resolved.

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Modifying the CSD JS for asynchronous loading

By default, the CSD JavaScript is configured to load synchronously and F5 highly recommends against changing this configuration. However, if there is a strong need, you can modify the CSD JavaScript to load asynchronously. To modify the CSD JavaScript for asynchronous loading, add async defer to the beginning of the script, as follows:

Change: <script src="https://us.gimp.zeronaught.com/js/example.js"></script>

To: <script async defer src="https://us.gimp.zeronaught.com/js/example.js"></script>

The CSD JavaScript should always be the first JavaScript or script to load on the web page to ensure that the CSD JavaScript can detect any malicious scripts running on the web page.

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Script versioning by name change

When you release a new version of a script with an updated name and path, you receive redundant alerts for the updated script. To stop the redundant alerts, contact F5 Support for information about how to define regex expressions that represent your script.

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