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Manual Chapter: Automatically Creating Security Policies for AJAX Applications
Manual Chapter
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Application security for applications that use AJAX

Application Security Manager™ can protect AJAX applications including those that use JSON or XML for data transfer between the client and the server. If the AJAX application uses XML for data transfer, the security policy requires that an XML profile be associated with a URL or parameter. If the AJAX application uses JSON for data transfer, the security policy requires that a JSON profile be associated with a URL or parameter. If the AJAX application uses HTTP for data transfer, no profile is needed.

You can also set up AJAX blocking response behavior for applications so that if a violation occurs during AJAX-generated traffic, the system displays a message or redirects the application user to another location.

Overview: Creating a security policy for applications that use AJAX

AJAX (Asynchronous JavaScript and XML) applications make requests to the server and send responses to the client formatted using XML or JavaScript Object Notation (JSON). You can create a security policy automatically for applications that use AJAX.

Task Summary

Creating a security policy automatically

Before you can create a security policy, you must perform the minimal system configuration tasks including defining a VLAN, a self IP address, and other tasks required according to the needs of your networking environment.
Application Security Manager™ can automatically create a security policy that is tailored to secure your web application.
  1. On the Main tab, click Security > Application Security > Security Policies. The Active Policies screen opens.
  2. Click the Create button. The Deployment wizard opens to the Select Local Traffic Deployment Scenario screen.
  3. For the Local Traffic Deployment Scenario setting, specify a virtual server to use for the security policy.
    • To secure an existing virtual server that has no security policy associated with it, select Existing Virtual Server and click Next.
    • To create a new virtual server and pool with basic configuration settings, select New Virtual Server and click Next.
    • To create an active but unused security policy, select Do not associate with Virtual Server and click Next. No traffic will go through this security policy until you associate it with a virtual server. The Policy Builder cannot begin automatically creating a policy until traffic is going to ASM through the virtual server.
    The virtual server represents the web application you want to protect. The Configure Local Traffic Settings screen opens.
  4. Configure the new or existing virtual server, and click Next.
    • If creating a new virtual server, specify the protocol, name, IP address and port, pool IP address, and port.
    • If using an existing virtual server, it must have an HTTP profile and cannot be associated with a local traffic policy.
    • If you select Do not associate with Virtual Server, you will have to manually associate the security policy with a virtual server at a later time. On the policy properties screen, you need to specify a name for the security policy.
    The name of the new or existing virtual server becomes the name of the security policy. The Select Deployment Scenario screen opens.
  5. For Deployment Scenario, select Create a policy automatically and click Next. The Configure Security Policy Properties screen opens.
  6. From the Application Language list, select the language encoding of the application, or select Auto detect and let the system detect the language.
    Important: You cannot change this setting after you have created the security policy.
  7. If the application is not case-sensitive, clear the Security Policy is case sensitive check box. Otherwise, leave it selected.
    Important: You cannot change this setting after you have created the security policy.
  8. If you do not want the security policy to distinguish between HTTP and HTTPS URLs, clear the Differentiate between HTTP and HTTPS URLs check box. Otherwise, leave it selected.
    Important: You cannot change this setting after you have created the security policy.
  9. Click Next. The Configure Attack Signatures screen opens.
  10. To configure attack signatures, move the systems used by your web application from the Available Systems list into the Assigned Systems list. The system adds the attack signatures needed to protect the selected systems.
  11. For the Signature Staging setting, verify that the default option Enabled is selected.
    Note: Because the Real Traffic Policy Builder® begins building the security policy in Blocking mode, you can keep signature staging enabled to make sure that false positives do not occur.
    New and updated attack signatures remain in staging for 7 days, and are not enforced (according to the learn, alarm, and block flags) during that time.
  12. Click Next. The Configure Automatic Policy Building screen opens.
  13. For Policy Type, select an option to determine the security features to include in the policy.
    Option Description
    Fundamental Creates a security policy enforcing HTTP protocol compliance, evasion techniques, explicit file types (including length checks), explicit parameters in selective mode at the global level, attack signatures, the violation Request Length Exceeds Defined Buffer Size, host names, header lengths, cookie lengths, and the violation Failed to Convert Character.
    Enhanced Creates a security policy with all the elements of the Fundamental policy type; also checks for explicit URLs in selective mode plus meta characters, Explicit parameter length checks in selective mode at the global level, methods, explicit cookies, and content profiles.
    Comprehensive Creates a security policy with all the elements of the Enhanced policy type; also checks for explicit URLs and meta characters, explicit parameters and lengths at the URL level, parameter meta characters, and dynamic parameters.
    A bulleted list on the screen describes which security features are included in each type.
  14. For Rules, move the slider to set the Policy Builder learning speed.
    Option Description
    Fast Use if your application supports a small number of requests from a small number of sessions; for example, useful for web sites with less traffic. However, choosing this option may present a greater chance of adding false entities to the security policy.
    Medium Use if your application supports a medium number of requests, or if you are not sure about the amount of traffic on the application web site. This is the default setting.
    Slow Use if your application supports a large number of requests from many sessions; for example, useful for web sites with lots of traffic. This option creates the most accurate security policy, but takes Policy Builder longer to collect the statistics.
    Based on the option you select, the system sets greater or lesser values for the number of different user sessions, different IP addresses, and length of time before it adds to the security policy and enforces the elements.
  15. For Trusted IP Addresses, select which IP addresses to consider safe:
    Option Description
    All Specifies that the policy trusts all IP addresses. For example, if the traffic is in a corporate lab or preproduction environment where all of the traffic is trusted, the policy is created faster when you select this option.
    Address List Specifies networks to consider safe. Fill in the IP Address and Netmask fields, then click Add. This option is typically used in a production environment where traffic could come from untrusted sources. The IP Address can be either an IPv4 or an IPv6 address.
    If you leave the trusted IP address list empty, the system treats all traffic as untrusted. In general, it takes more untrusted traffic, from different IP addresses, over a longer period of time to build a security policy.
  16. If you want the security policy to automatically detect JSON and XML protocols, select the JSON/XML payload detection check box. If requests contain legitimate XML or JSON data, the Policy Builder creates content profiles in the security policy according to the data it detects.
  17. If you want to display a response page when an AJAX request does not adhere to the security policy, select the AJAX blocking response behavior check box.
  18. Click Next. The Security Policy Configuration Summary opens where you can review the settings to be sure they are correct.
  19. Click Finish to create the security policy. The Automatic Policy Building Status screen opens where you can view the current state of the security policy.
ASM™ creates the virtual server with an HTTP profile, and on the Security tab, Application Security Policy is enabled and associated with the security policy you created. A local traffic policy is also created and by default sends all traffic for the virtual server to ASM. The Policy Builder automatically begins examining the traffic to the web application and building the security policy (unless you did not associate a virtual server). The system sets the enforcement mode of the security policy to Blocking, but it does not block requests until the Policy Builder processes sufficient traffic, adds elements to the security policy, and enforces the elements.
Tip: This is a good point at which to test that you can access the application being protected by the security policy and check that traffic is being processed by the BIG-IP® system.

Reviewing security policy status

You can monitor the general progress of the Real Traffic Policy Builder®, see what policy elements the system has learned, and view additional details on the Automatic Policy Building Status screen.
  1. On the Main tab, click Security > Application Security > Policy Building > Status (Automatic). The Status (Automatic) screen opens where you can see the automatic policy building status, file types, URLs, parameters, and cookies that were added to the security policy.
  2. In the Current edited policy list near the top of the screen, verify that the edited security policy is the one you want to work on.
  3. Review any messages in the identification and messages area to learn what is currently happening on the system. For example, messages say when the Policy Builder is enabled, when the security policy was last updated, and the number of elements that were learned.
  4. Review the status of the Real Traffic Policy Builder.
    Option Description
    Enabled The system is configured to automatically build a security policy, and the Policy Builder is processing traffic.
    Disabled The system is not processing traffic. Check the automatic policy building configuration. If you did not associate a virtual server, you need to do that to process traffic.
    Detecting Language The system is still configuring the language after analyzing responses to identify the language of the web application. The Policy Builder is enabled, but it cannot add elements to the security policy until the language is set.
  5. Examine the General Progress of the security policy. A progress bar indicates the stability level of the security policy. The progress bar reaches 100% when the policy is stable, no new policy elements need to be added, and time and traffic thresholds have been reached.
  6. In the Policy Elements Learned table, review the number of elements that the Policy Builder has analyzed and added to the security policy, and the attributes that need to be updated.
    Tip: Click the number in the Elements column to see the specific elements that were added.
  7. Optionally, in the Details tree view, click the expand button for any item to learn more about that security policy element, what the system has seen so far, and what it will take to stabilize the element.
When enough traffic from unique sessions occurs over a period of time, the system starts to enforce the file types and other elements in the security policy. When enforced as part of a stable policy, the files types and other elements are removed from staging.

Implementation result

The Real Traffic Policy Builder® creates a security policy that can protect applications that use AJAX with JSON or XML for data transfer between the client and the server. The system examines the traffic and creates an appropriate profile. If the application uses XML, the security policy includes one or more XML profiles associated with URLs or parameters. If the application uses JSON, the security policy includes one or more JSON profiles associated with URLs or parameters.

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