=begin
    Copyright 2010-2013 Tasos Laskos <tasos.laskos@gmail.com>

    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at

        http://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
=end

#
# It's designed to work with PHP, Perl, Python, Java, ASP and Ruby
# but still needs some more testing.
#
#
# @author Tasos "Zapotek" Laskos <tasos.laskos@gmail.com>
#
# @version 0.2
#
# @see http://cwe.mitre.org/data/definitions/94.html
# @see http://php.net/manual/en/function.eval.php
# @see http://perldoc.perl.org/functions/eval.html
# @see http://docs.python.org/py3k/library/functions.html#eval
# @see http://www.aspdev.org/asp/asp-eval-execute/
# @see http://en.wikipedia.org/wiki/Eval#Ruby
#
class Arachni::Modules::CodeInjection < Arachni::Module::Base

    def self.rand1
        @rand1 ||= '287630581954'
    end

    def self.rand2
        @rand2 ||= '4196403186331128'
    end

    def self.options
        @options ||= {
            substring: (rand1.to_i + rand2.to_i).to_s,
            format:    [Format::APPEND, Format::STRAIGHT],
            param_flip: false
        }
    end

    def self.code_strings
        # code strings to be injected to the webapp
        @code_strings ||= {
            php:    "echo #{rand1}+#{rand2};",
            perl:   "print #{rand1}+#{rand2};",
            python: "print #{rand1}+#{rand2}",
            asp:    "Response.Write\x28#{rand1}+#{rand2}\x29"
        }
    end

    def self.payloads
        return @payloads if @payloads

        @payloads = {}
        code_strings.each do |platform, payload|
            @payloads[platform] = [ ';%s', "\";%s#", "';%s#" ].
                map { |var| var % payload } | [payload]
        end
        @payloads
    end

    def run
        audit( self.class.payloads, self.class.options )
    end

    def self.info
        {
            name:        'Code injection',
            description: %q{It tries to inject code snippets into the
                web application and assess whether or not the injection
                was successful.},
            elements:    [ Element::FORM, Element::LINK, Element::COOKIE, Element::HEADER ],
            author:      'Tasos "Zapotek" Laskos <tasos.laskos@gmail.com>',
            version:     '0.2',
            references:  {
                'PHP'    => 'http://php.net/manual/en/function.eval.php',
                'Perl'   => 'http://perldoc.perl.org/functions/eval.html',
                'Python' => 'http://docs.python.org/py3k/library/functions.html#eval',
                'ASP'    => 'http://www.aspdev.org/asp/asp-eval-execute/',
            },
            targets:     %w(PHP Perl Python ASP),
            issue:       {
                name:            %q{Code injection},
                description:     %q{Arbitrary code can be injected into the web application
    which is then executed as part of the system.},
                tags:            %w(code injection regexp),
                cwe:             '94',
                severity:        Severity::HIGH,
                cvssv2:          '7.5',
                remedy_guidance: %q{User inputs must be validated and filtered
    before being evaluated as executable code.
    Better yet, the web application should stop evaluating user
    inputs as any part of dynamic code altogether.},
                remedy_code:     '',
                metasploitable:  'unix/webapp/arachni_php_eval'
            }

        }
    end

end