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 TargetString
before inspecting a request for a match.
You can only specify a single type of TextTransformation.
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.
NONE
Specify NONE
if you don't want to perform any text transformations.