rnd_hex_encode

2013-06-10T23:02:10
ID W3AF:271EAC411A08378527C3ECB96C3D9D19
Type w3af
Reporter andresriancho
Modified 2015-05-21T18:08:57

Description

This evasion plugin adds random hex encoding. Example: Input: '/bar/foo.asp' Output : '/b%61r/%66oo.asp'

Plugin type

Evasion

Options

This plugin doesn't have any user configured options.

Source

For more information about this plugin and the associated tests, there's always the source code to understand exactly what's under the hood:
Plugin source code
Unittest source code

Dependencies

This plugin has no dependencies.

                                        
                                            """
rnd_hex_encode.py

Copyright 2006 Andres Riancho

This file is part of w3af, http://w3af.org/ .

w3af is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation version 2 of the License.

w3af is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with w3af; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

"""
from random import randint

from w3af.core.controllers.plugins.evasion_plugin import EvasionPlugin
from w3af.core.data.parsers.doc.url import parse_qs
from w3af.core.data.url.HTTPRequest import HTTPRequest as HTTPRequest


class rnd_hex_encode(EvasionPlugin):
    """
    Add random hex encoding.
    :author: Andres Riancho (andres.riancho@gmail.com)
    """

    def __init__(self):
        EvasionPlugin.__init__(self)

    def modify_request(self, request):
        """
        Mangles the request

        :param request: HTTPRequest instance that is going to be modified
                        by the evasion plugin
        :return: The modified request
        """
        # First we mangle the URL
        path = request.url_object.get_path()
        path = self._mutate(path)

        # Finally, we set all the mutants to the request in order to return it
        new_url = request.url_object.copy()
        new_url.set_path(path)

        # Mangle the postdata
        data = request.get_data()
        if data:

            try:
                # Only mangle the postdata if it is a url encoded string
                parse_qs(data)
            except:
                pass
            else:
                data = self._mutate(data)

        new_req = HTTPRequest(new_url, data, request.headers,
                              request.get_origin_req_host(),
                              retries=request.retries_left)

        return new_req

    def _mutate(self, data):
        """
        Replace some strings by it's hex encoded value.

        :return: a string.
        """
        new_data = ''
        for char in data:
            if char not in ['?', '/', '&', '\\', '=', '%', '+']:
                if randint(1, 2) == 2:
                    char = "%%%02x" % ord(char)
            new_data += char
        return new_data

    def get_priority(self):
        """
        This function is called when sorting evasion plugins.
        Each evasion plugin should implement this.

        :return: An integer specifying the priority. 0 is run first, 100 last.
        """
        return 50

    def get_long_desc(self):
        """
        :return: A DETAILED description of the plugin functions and features.
        """
        return """
        This evasion plugin adds random hex encoding.

        Example:
            Input:      '/bar/foo.asp'
            Output :    '/b%61r/%66oo.asp'
        """