AWS CloudFormation
User Guide (Version )

AWS::WAF::SizeConstraintSet SizeConstraint

Note

This is AWS WAF Classic documentation. For more information, see AWS WAF Classic in the developer guide.

For the latest version of AWS WAF, use the AWS WAFV2 API and see the AWS WAF Developer Guide. With the latest version, AWS WAF has a single set of endpoints for regional and global use.

Specifies a constraint on the size of a part of the web request. AWS WAF uses the Size, ComparisonOperator, and FieldToMatch to build an expression in the form of "Size ComparisonOperator size in bytes of FieldToMatch". If that expression is true, the SizeConstraint is considered to match.

Syntax

To declare this entity in your AWS CloudFormation template, use the following syntax:

JSON

{ "ComparisonOperator" : String, "FieldToMatch" : FieldToMatch, "Size" : Integer, "TextTransformation" : String }

Properties

ComparisonOperator

The type of comparison you want AWS WAF to perform. AWS WAF uses this in combination with the provided Size and FieldToMatch to build an expression in the form of "Size ComparisonOperator size in bytes of FieldToMatch". If that expression is true, the SizeConstraint is considered to match.

EQ: Used to test if the Size is equal to the size of the FieldToMatch

NE: Used to test if the Size is not equal to the size of the FieldToMatch

LE: Used to test if the Size is less than or equal to the size of the FieldToMatch

LT: Used to test if the Size is strictly less than the size of the FieldToMatch

GE: Used to test if the Size is greater than or equal to the size of the FieldToMatch

GT: Used to test if the Size is strictly greater than the size of the FieldToMatch

Required: Yes

Type: String

Allowed Values: EQ | GE | GT | LE | LT | NE

Update requires: No interruption

FieldToMatch

Specifies where in a web request to look for the size constraint.

Required: Yes

Type: FieldToMatch

Update requires: No interruption

Size

The size in bytes that you want AWS WAF to compare against the size of the specified FieldToMatch. AWS WAF uses this in combination with ComparisonOperator and FieldToMatch to build an expression in the form of "Size ComparisonOperator size in bytes of FieldToMatch". If that expression is true, the SizeConstraint is considered to match.

Valid values for size are 0 - 21474836480 bytes (0 - 20 GB).

If you specify URI for the value of Type, the / in the URI counts as one character. For example, the URI /logo.jpg is nine characters long.

Required: Yes

Type: Integer

Update requires: No interruption

TextTransformation

Text transformations eliminate some of the unusual formatting that attackers use in web requests in an effort to bypass AWS WAF. If you specify a transformation, AWS WAF performs the transformation on FieldToMatch before inspecting it for a match.

You can only specify a single type of TextTransformation.

Note that if you choose BODY for the value of Type, you must choose NONE for TextTransformation because CloudFront forwards only the first 8192 bytes for inspection.

NONE

Specify NONE if you don't want to perform any text transformations.

CMD_LINE

When you're concerned that attackers are injecting an operating system command line command and using unusual formatting to disguise some or all of the command, use this option to perform the following transformations:

  • Delete the following characters: \ " ' ^

  • Delete spaces before the following characters: / (

  • Replace the following characters with a space: , ;

  • Replace multiple spaces with one space

  • Convert uppercase letters (A-Z) to lowercase (a-z)

COMPRESS_WHITE_SPACE

Use this option to replace the following characters with a space character (decimal 32):

  • \f, formfeed, decimal 12

  • \t, tab, decimal 9

  • \n, newline, decimal 10

  • \r, carriage return, decimal 13

  • \v, vertical tab, decimal 11

  • non-breaking space, decimal 160

COMPRESS_WHITE_SPACE also replaces multiple spaces with one space.

HTML_ENTITY_DECODE

Use this option to replace HTML-encoded characters with unencoded characters. HTML_ENTITY_DECODE performs the following operations:

  • Replaces (ampersand)quot; with "

  • Replaces (ampersand)nbsp; with a non-breaking space, decimal 160

  • Replaces (ampersand)lt; with a "less than" symbol

  • Replaces (ampersand)gt; with >

  • Replaces characters that are represented in hexadecimal format, (ampersand)#xhhhh;, with the corresponding characters

  • Replaces characters that are represented in decimal format, (ampersand)#nnnn;, with the corresponding characters

LOWERCASE

Use this option to convert uppercase letters (A-Z) to lowercase (a-z).

URL_DECODE

Use this option to decode a URL-encoded value.

Required: Yes

Type: String

Allowed Values: CMD_LINE | COMPRESS_WHITE_SPACE | HTML_ENTITY_DECODE | LOWERCASE | NONE | URL_DECODE

Update requires: No interruption

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