David Bartle > Template-Directive-XSSAudit-1.03 > Template::Directive::XSSAudit

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Module Version: 1.03   Source  

NAME ^

Template::Directive::XSSAudit - TT2 output filtering lint testing

SYNOPSIS ^

  use Template;
  use Template::Directive::XSSAudit;

  my $tt = Template->new({
      FACTORY => "Template::Directive::XSSAudit"
  });

  my $input = <<'END';
  Hello [% exploitable.goodness %] World!
  How would you like to [% play.it.safe | html %] today?
  END

  my $out  = '';
  $tt->process(\$input, {}, \$out) || die $tt->error();

  # output on STDOUT... via default on_error handler
  # see the documentation of on_error for explanation of the
  # output format of the default error handler
  #input file   NO_FILTERS  line:1    exploitable.goodness

DESCRIPTION ^

This module will help you perform basic lint tests of your template toolkit files.

It is intended to parse through all GET items, and make sure that at least one "good" filter is used to escape it.

A callback may be provided so that the errors may be handled in a way that makes sense for the project at hand. See on_error for more details.

There is another callback which can be provided named on_filtered. This is triggered when a variable is successfully filtered. By default there is no implementation. See on_filtered for more details.

Additionally, a list of filter names may be provided, instructing the module to require that certain filters be used for output escaping in the tests.

Have a look at the t/*.t files that come with the distribution as they leverage the on_error() callback routine.

IMPORTANT NOTES ON SECURITY ^

This tool is NOT a substitude for code and security reviews as it is NOT context aware. This means if you use a html filter in javascript context or css context or html attribute context, you would not be escaping things properly and this tool would not catch that.

You also need to make sure that your "good" filters are actually doing their job and escaping things properly.

All of this to say, don't let this give you a false sense of security.

EXPORTS ^

None.

METHODS ^

Template::Directive::XSSAudit->on_error ( [ coderef ] )

This method is called on every variable involved in a template toolkit 'GET' which was not filtered properly.

The callback will be executed in one of two cases:

 - The variable in question has NO output filtering
 - The variable is filtered but none of the filters 
   were found in the C<good_filter> list.

A default implementation is provided which will simply warn any problems which are found with the following information (tab delimited):

  <file_name> <error_type> line:<line_no> <filters used csv>

If you call this method without a subroutine reference, it will simply return you the current implementation.

If you provide your own callback, it will be passed one parameter which is a hash reference containing the following keys.

variable_name

This is a string represending the variable name which was found to be incorrectly escaped.

filtered_by

This will contain an array reference containing the names of the filters which were applied to the variable name.

If there are entries in this list, it means that no filter in the good filter list was found to apply to the variable. See good_filter for more information.

In the case of variables with no filters, this will be an empty array reference.

file_name

The line number in the template file where the problem occurred.

This is parsed out as best as can be done but it may come back as an empty string in many cases. It is a convenience item and should not be relied on for any sort of automation.

file_line

The line number in the template file where the problem occurred.

This is parsed out as best as can be done but it may come back as an empty string in many cases. It is a convenience item and should not be relied on for any sort of automation.

Template::Directive::XSSAudit->on_filtered ( [ coderef ] )

This method is called on every variable involved in a template toolkit 'GET' which was filtered satisfactorily.

By default, no implementation is given so if you want this to do anything, you'll have to provide a coderef yourself.

The callback and function works just like on_error so see the documentation for that method for more details.

Template::Directive::XSSAudit->good_filters ( [ arrayref ] )

This method will return the current list of "good" filters to you as an array reference. eg.

  [ 'html', 'uri' ]

If you pass an array reference of strings, it will also set the list of good filters. The defaults are simply 'html' and 'uri' but I will be adding more int the future.

SEE ALSO ^

Template http://github.com/captin411/template-directive-xssaudit/ http://www.owasp.org/index.php/Category:OWASP_Encoding_Project/ http://ha.ckers.org/xss.html

BUGS ^

Please report bugs using the CPAN Request Tracker at http://rt.cpan.org/

AUTHOR ^

David Bartle <dbartle@mediatemple.net>

This work was sponsored by my employer, (mt) Media Temple, Inc.

COPYRIGHT ^

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

The full text of the license can be found in the LICENSE file included with this module.

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