Class: Aws::WAFV2::Types::ByteMatchStatement

Inherits:
Struct
  • Object
show all
Includes:
Structure
Defined in:
lib/aws-sdk-wafv2/types.rb

Overview

A rule statement that defines a string match search for WAF to apply to web requests. The byte match statement provides the bytes to search for, the location in requests that you want WAF to search, and other settings. The bytes to search for are typically a string that corresponds with ASCII characters. In the WAF console and the developer guide, this is called a string match statement.

See Also:

Constant Summary collapse

SENSITIVE = 
[]

Instance Attribute Summary collapse

Instance Attribute Details

#field_to_match ⇒ Types::FieldToMatch

The part of the web request that you want WAF to inspect.

Returns:



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# File 'lib/aws-sdk-wafv2/types.rb', line 665

class ByteMatchStatement < Struct.new(
  :search_string,
  :field_to_match,
  :text_transformations,
  :positional_constraint)
  SENSITIVE = []
  include Aws::Structure
end

#positional_constraint ⇒ String

The area within the portion of the web request that you want WAF to search for ‘SearchString`. Valid values include the following:

CONTAINS

The specified part of the web request must include the value of ‘SearchString`, but the location doesn’t matter.

CONTAINS_WORD

The specified part of the web request must include the value of ‘SearchString`, and `SearchString` must contain only alphanumeric characters or underscore (A-Z, a-z, 0-9, or _). In addition, `SearchString` must be a word, which means that both of the following are true:

  • ‘SearchString` is at the beginning of the specified part of the web request or is preceded by a character other than an alphanumeric character or underscore (_). Examples include the value of a header and `;BadBot`.

  • ‘SearchString` is at the end of the specified part of the web request or is followed by a character other than an alphanumeric character or underscore (_), for example, `BadBot;` and `-BadBot;`.

EXACTLY

The value of the specified part of the web request must exactly match the value of ‘SearchString`.

STARTS_WITH

The value of ‘SearchString` must appear at the beginning of the specified part of the web request.

ENDS_WITH

The value of ‘SearchString` must appear at the end of the specified part of the web request.

Returns:

  • (String) 


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# File 'lib/aws-sdk-wafv2/types.rb', line 665

class ByteMatchStatement < Struct.new(
  :search_string,
  :field_to_match,
  :text_transformations,
  :positional_constraint)
  SENSITIVE = []
  include Aws::Structure
end

#search_string ⇒ String

A string value that you want WAF to search for. WAF searches only in the part of web requests that you designate for inspection in FieldToMatch. The maximum length of the value is 200 bytes.

Valid values depend on the component that you specify for inspection in ‘FieldToMatch`:

  • ‘Method`: The HTTP method that you want WAF to search for. This indicates the type of operation specified in the request.

  • ‘UriPath`: The value that you want WAF to search for in the URI path, for example, `/images/daily-ad.jpg`.

  • ‘JA3Fingerprint`: Available for use with Amazon CloudFront distributions and Application Load Balancers. Match against the request’s JA3 fingerprint. The JA3 fingerprint is a 32-character hash derived from the TLS Client Hello of an incoming request. This fingerprint serves as a unique identifier for the client’s TLS configuration. You can use this choice only with a string match ‘ByteMatchStatement` with the `PositionalConstraint` set to `EXACTLY`.

    You can obtain the JA3 fingerprint for client requests from the web ACL logs. If WAF is able to calculate the fingerprint, it includes it in the logs. For information about the logging fields, see [Log fields] in the *WAF Developer Guide*.

  • ‘HeaderOrder`: The list of header names to match for. WAF creates a string that contains the ordered list of header names, from the headers in the web request, and then matches against that string.

If ‘SearchString` includes alphabetic characters A-Z and a-z, note that the value is case sensitive.

**If you’re using the WAF API**

Specify a base64-encoded version of the value. The maximum length of the value before you base64-encode it is 200 bytes.

For example, suppose the value of ‘Type` is `HEADER` and the value of `Data` is `User-Agent`. If you want to search the `User-Agent` header for the value `BadBot`, you base64-encode `BadBot` using MIME base64-encoding and include the resulting value, `QmFkQm90`, in the value of `SearchString`.

**If you’re using the CLI or one of the Amazon Web Services SDKs**

The value that you want WAF to search for. The SDK automatically base64 encodes the value.

[1]: docs.aws.amazon.com/waf/latest/developerguide/logging-fields.html

Returns:

  • (String) 


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# File 'lib/aws-sdk-wafv2/types.rb', line 665

class ByteMatchStatement < Struct.new(
  :search_string,
  :field_to_match,
  :text_transformations,
  :positional_constraint)
  SENSITIVE = []
  include Aws::Structure
end

#text_transformations ⇒ Array<Types::TextTransformation>

Text transformations eliminate some of the unusual formatting that attackers use in web requests in an effort to bypass detection. Text transformations are used in rule match statements, to transform the ‘FieldToMatch` request component before inspecting it, and they’re used in rate-based rule statements, to transform request components before using them as custom aggregation keys. If you specify one or more transformations to apply, WAF performs all transformations on the specified content, starting from the lowest priority setting, and then uses the transformed component contents.

Returns:



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# File 'lib/aws-sdk-wafv2/types.rb', line 665

class ByteMatchStatement < Struct.new(
  :search_string,
  :field_to_match,
  :text_transformations,
  :positional_constraint)
  SENSITIVE = []
  include Aws::Structure
end