JSONThreatProtection policy

What

Minimizes the risk posed by content-level attacks by enabling you to specify limits on various JSON structures, such as arrays and strings.

Video: Watch a short video to learn more about how the JSON Threat Protection policy enables you to secure APIs against content-level attacks.

Watch a short video on threat protection

Video: Check out this short video about threat protection policies.

Element reference

The element reference describes the elements and attributes of the JSONThreatProtection policy.

<JSONThreatProtection async="false" continueOnError="false" enabled="true" name="JSON-Threat-Protection-1">
   <DisplayName>JSON Threat Protection 1</DisplayName>
   <ArrayElementCount>20</ArrayElementCount>
   <ContainerDepth>10</ContainerDepth>
   <ObjectEntryCount>15</ObjectEntryCount>
   <ObjectEntryNameLength>50</ObjectEntryNameLength>
   <Source>request</Source>
   <StringValueLength>500</StringValueLength>
</JSONThreatProtection>

<JSONThreatProtection> attributes

<JSONThreatProtection async="false" continueOnError="false" enabled="true" name="JSON-Threat-Protection-1"> 

The following table describes attributes that are common to all policy parent elements:

Attribute Description Default Presence
name

The internal name of the policy. The value of the name attribute can contain letters, numbers, spaces, hyphens, underscores, and periods. This value cannot exceed 255 characters.

Optionally, use the <DisplayName> element to label the policy in the management UI proxy editor with a different, natural-language name.

N/A Required
continueOnError

Set to false to return an error when a policy fails. This is expected behavior for most policies.

Set to true to have flow execution continue even after a policy fails.

false Optional
enabled

Set to true to enforce the policy.

Set to false to "turn off" the policy. The policy will not be enforced even if it remains attached to a flow.

true Optional
async

This attribute is deprecated.

false Deprecated

<DisplayName> element

Use in addition to the name attribute to label the policy in the management UI proxy editor with a different, natural-language name.

<DisplayName>Policy Display Name</DisplayName>
Default:

N/A

If you omit this element, the value of the policy's name attribute is used.

Presence: Optional
Type: String

<ArrayElementCount> element

Specifies the maximum number of elements allowed in an array.

<ArrayElementCount>20</ArrayElementCount>
Default: If you do not specify this element, or if you specify a negative integer, the system does not enforce a limit.
Presence: Optional
Type: Integer

<ContainerDepth> element

Specifies the maximum allowed containment depth, where the containers are objects or arrays. For example, an array containing an object which contains an object would result in a containment depth of 3.

<ContainerDepth>10</ContainerDepth>
Default: If you do not specify this element, or if you specify a negative integer, the system does not enforce any limit.
Presence: Optional
Type: Integer

<ObjectEntryCount> element

Specifies the maximum number of entries allowed in an object.

<ObjectEntryCount>15</ObjectEntryCount>
Default: If you do not specify this element, or if you specify a negative integer, the system does not enforce any limit.
Presence: Optional
Type: Integer

<ObjectEntryNameLength> element

Specifies the maximum string length allowed for a property name within an object.

<ObjectEntryNameLength>50</ObjectEntryNameLength>
Default: If you do not specify this element, or if you specify a negative integer, the system does not enforce a limit.
Presence: Optional
Type: Integer

<Source> element

Message to be screened for JSON payload attacks. This is most commonly set to request, as you will typically need to validate inbound requests from client apps. When set to message, this element will automatically evaluate the request message when attached to the request flow and the response message when attached to the response flow.

<Source>request</Source>
Default: request
Presence: Optional
Type:

String.

Valid values: request, response, or message.

<StringValueLength> element

Specifies the maximum length allowed for a string value.

<StringValueLength>500</StringValueLength>
Default: If you do not specify this element, or if you specify a negative integer, the system does not enforce a limit.
Presence: Optional
Type: Integer

Error reference

This section describes the fault codes and error messages that are returned and fault variables that are set by Edge when this policy triggers an error. This information is important to know if you are developing fault rules to handle faults. To learn more, see What you need to know about policy errors and Handling faults.

Runtime errors

These errors can occur when the policy executes.

Fault code HTTP status Cause Fix
steps.jsonthreatprotection.ExecutionFailed 500 The JSONThreatProtection policy can throw many different types of ExecutionFailed errors. Most of these errors occur when a specific threshold set in the policy is exceeded. These types of errors include: object entry name length, object entry count, array element count, container depth, string string value length. This error also occurs when the payload contains an invalid JSON object. build
steps.jsonthreatprotection.SourceUnavailable 500 This error occurs if the message variable specified in the <Source> element is either:
  • Out of scope (not available in the specific flow where the policy is being executed)
  • Is not one of the valid values request, response, or message
build
steps.jsonthreatprotection.NonMessageVariable 500 This error occurs if the <Source> element is set to a variable which is not of type message. build

Deployment errors

None.

Fault variables

These variables are set when this policy triggers an error. For more information, see What you need to know about policy errors.

Variables Where Example
fault.name="fault_name" fault_name is the name of the fault, as listed in the Runtime errors table above. The fault name is the last part of the fault code. fault.name Matches "SourceUnavailable"
jsonattack.policy_name.failed policy_name is the user-specified name of the policy that threw the fault. jsonattack.JTP-SecureRequest.failed = true

Example error response

{
  "fault": {
    "faultstring": "JSONThreatProtection[JPT-SecureRequest]: Execution failed. reason: JSONThreatProtection[JTP-SecureRequest]: Exceeded object entry name length at line 2",
    "detail": {
      "errorcode": "steps.jsonthreatprotection.ExecutionFailed"
    }
  }
}

Example fault rule

<FaultRule name="JSON Threat Protection Policy Faults">
    <Step>
        <Name>AM-CustomErrorResponse</Name>
        <Condition>(fault.name Matches "ExecutionFailed") </Condition>
    </Step>
    <Condition>(jsonattack.JPT-SecureRequest.failed = true) </Condition>
</FaultRule>

Schemas

Usage notes

Like XML-based services, APIs that support JavaScript object notation (JSON) are vulnerable to content-level attacks. Simple JSON attacks attempt to use structures that overwhelm JSON parsers to crash a service and induce application-level denial-of-service attacks. All settings are optional and should be tuned to optimize your service requirements against potential vulnerabilities.

Related topics

JSON to XML policy

XML Threat Protection policy

Regular Expression Protection policy