backspace_between_dots

2013-06-10T23:02:10
ID W3AF:C80286C4ECDAEE7ED0B54FA451B283D2
Type w3af
Reporter andresriancho
Modified 2019-04-01T16:42:01

Description

This evasion plugin inserts an 'A' and a backspace control character between dots which cancel each other when they are processed and some filters that match '../' are bypassed. Example: Input: '../../etc/passwd' Output: '.%41%08./.%41%08./etc/passwd'

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.

                                        
                                            """
backspace_between_dots.py

Copyright 2008 Jose Ramon Palanco

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 w3af.core.controllers.plugins.evasion_plugin import EvasionPlugin


class backspace_between_dots(EvasionPlugin):
    """
    Insert between dots an 'A' and an BS control character which are cancelled
    each other when they are below

    :author: Jose Ramon Palanco( jose.palanco@hazent.com )
    """
    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
        """
        # We mangle the URL
        path = request.url_object.get_path()
        path = path.replace('/../', '/.%41%08./')

        # 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)

        new_req = request.copy()
        new_req.set_uri(new_url)

        return new_req

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

        :return: An integer specifying the priority. 100 is run first, 0 last.
        """
        return 20

    def get_long_desc(self):
        """
        :return: A DETAILED description of the plugin functions and features.
        """
        return r"""
        This evasion plugin inserts an 'A' and a backspace control character
        between dots which cancel each other when they are processed and some
        filters that match '../' are bypassed.

        Example:
            Input:      '../../etc/passwd'
            Output:     '.%41%08./.%41%08./etc/passwd'
        """