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Manual Chapter : Adding JSON Support to an Existing Security Policy

Applies To:

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BIG-IP ASM

  • 13.0.0
Manual Chapter
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Overview: Adding JSON support to existing security policies

JSON (JavaScript® Object Notation) is a data-interchange format often used to pass data back and forth between an application and a server. This implementation describes how to add JSON support to an existing security policy for an application that uses JSON for data transfer. You create a JSON profile to define what the security policy enforces and considers legal when it detects traffic that contains JSON data.

You add JSON support to a security policy by completing these tasks.

Task Summary

Creating a JSON profile

Before you can complete this task, you need to have already created a security policy for your application.
This task describes how to create a JSON profile that defines the properties that the security policy enforces for an application sending JSON payloads or WebSocket payloads in JSON format.
Note: The system supports JSON in UTF-8 and UTF-16 encoding. WebSocket allows only UTF-8.
  1. On the Main tab, click Security > Application Security > Content Profiles > JSON Profiles .
  2. Click Create to create a new JSON profile, or edit the Default JSON profile (by clicking it).
    The Create New JSON Profile screen opens.
  3. Type a name for the profile.
  4. Adjust the maximum values that define the JSON data for the AJAX application, or use the default values.
  5. If you want the system to tolerate and not report warnings about JSON content, select the Tolerate JSON Parsing Warnings check box.
    If the system cannot parse JSON content, it generates the violation Malformed JSON data, regardless of whether this setting is enabled or disabled.
  6. To parse parameters in a JSON payload as parameters (recommended), ensure that Parse Parameters is enabled.
    The system extracts parameters from JSON content whenever the JSON profile is used; for example, with URLs, WebSocket URLs, or parameters that use a JSON profile.
    The security policy parses parameters extracted from the JSON payload the same as other parameters. Also, the Attack Signatures, Value Metacharacters, and Sensitive Data Configuration tabs are removed from the screen, so you can skip to the last step.
  7. If the signatures included in the security policy are not sufficient for this JSON profile, you can change them.
    1. On the Attack Signatures tab, in the Global Security Policy Settings list, select any specific attack signatures that you want to enable or disable for this profile, and then move them into the Overridden Security Policy Settings list.
      Tip: If no attack signatures are listed in the Global Security Policy Settings list, create the profile, update the attack signatures, then edit the profile.
    2. After you have moved any applicable attack signatures to the Overridden Security Policy Settings list, enable or disable each of them as needed:
      • Enabled - Enforces the attack signature for this JSON profile, although the signature might be disabled in general. The system reports the violation Attack Signature Detected when the JSON in a request matches the attack signature.
      • Disabled - Disables the attack signature for this JSON profile, although the signature might be enabled in general.
  8. To allow or disallow specific meta characters in JSON data (and thus override the global meta character settings), click the Value Meta Characters tab.
    • Select the Check characters check box, if it is not already selected.
    • Move any meta characters that you want allow or disallow from the Global Security Policy Settings list into the Overridden Security Policy Settings list.
    • In the Overridden Security Policy Settings list, change the meta character state to Allow or Disallow.
  9. To mask sensitive JSON data (replacing it with asterisks), click the Sensitive Data Configuration tab.
    • In the Element Name field, type the JSON element whose values you want the system to consider sensitive.
    • Click Add.
    Important: If the JSON data causes violations and the system stops parsing the data part way through a transaction, the system masks only the sensitive data that was fully parsed.
    Add any other elements that could contain sensitive data that you want to mask.
  10. Click Create (or Update if editing the Default profile).
    The system creates the profile and displays it in the JSON Profiles list.
This creates a JSON profile that affects the security policy when you associate the profile with a URL, WebSocket URL, or parameter.
Next, you need to associate the JSON profile with any URLs, WebSocket URLs, or parameters that might include JSON data.

Associating a JSON profile with a URL

Before you can associate a JSON profile with a URL, you need to have created a security policy with policy elements including application URLs, and the JSON profile.
You can associate a JSON profile with one or more explicit or wildcard URLs.
  1. On the Main tab, click Security > Application Security > URLs .
  2. In the Current edited security policy list near the top of the screen, verify that the security policy shown is the one you want to work on.
  3. From the Allowed URLs List, click the name of a URL that might contain JSON data.
    The Allowed URL Properties screen opens.
  4. Next to Allowed URL Properties, select Advanced.
    The screen refreshes to display additional configuration options.
  5. Click the Header-Based Content Profiles tab, and in the Request Header Name field, type the explicit string or header name that defines when the request is treated as the Parsed As type; for example, content-type.
    This field is not case sensitive.
    Note: If the URL always contains JSON data, for Request Body Handling select JSON.
  6. In the Request Header Value field, type the wildcard (including *, ?, or [chars]) for the header value that must be matched in the Request Header Name field; for example, *json*.
    This field is case sensitive.
  7. From the Request Body Handling list, select JSON.
    The system automatically creates a Default JSON profile, and assigns it as the profile when you select JSON in this field.
  8. From the Profile Name list, either leave the default, select a JSON profile appropriate for this URL, or click Create to quickly create a new JSON profile.
  9. Click Add.
    Add as many header types as you need to secure this URL, clicking Add after specifying each one.
  10. To override the global meta character settings for this URL, adjust the meta character policy settings:
    • In the Meta Characters tab, select the Check characters on this URL check box, if it is not already selected.
    • Move any meta characters that you want allow or disallow from the Global Security Policy Settings list into the Overridden Security Policy Settings list.
    • In the Overridden Security Policy Settings list, change the meta character state to Allow or Disallow.
  11. Click Update.
  12. To put the security policy changes into effect immediately, click Apply Policy.
The JSON profile is associated with the URL.
Continue to associate JSON profiles with any URLs in the application that might contain JSON data.

Associating a JSON profile with a parameter

You need to have created a security policy with policy elements including parameters and a JSON profile before starting this procedure.
You can associate a JSON profile with a parameter.
  1. On the Main tab, click Security > Application Security > Parameters .
  2. In the Current edited security policy list near the top of the screen, verify that the security policy shown is the one you want to work on.
  3. In the Parameters List area, click the name of a parameter to which to assign a JSON profile.
    The Parameter Properties screen opens.
  4. For the Parameter Value Type setting, select JSON value.
    The system automatically creates a Default JSON profile, and assigns it as the profile when you select JSON value in this field.
  5. From the JSON Profile list, either leave the default, select a JSON profile appropriate for this parameter, or click Create to quickly create a new JSON profile for this parameter.
  6. Click Update.
    The system associates the JSON profile with the parameter.
  7. To put the security policy changes into effect immediately, click Apply Policy.
Continue to associate JSON profiles with any parameters in the application that might contain JSON data.

Implementation result

You have manually added JSON support to the active security policy. The policy can now secure applications that use JSON for data transfer between the client and the server. If web application traffic includes JSON data, the system checks that it meets the requirements that you specified in the JSON profile.

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